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Article

Discovering New B[e] Supergiants and Candidate Luminous Blue Variables int Nearby Galaxies

by
Grigoris Maravelias
1,2,*,
Stephan de Jokes
1,3,
Alceste Z. Bonanos
1,
Frank Tramper
4,
Gonzalo Munoz-Sanchez
1,3 and
Evangelia Christodoulou
1,3
1
IAASARS, International Observatory of Athinai, GR-15326 Penteli, Greece
2
Institute of Astrophysics FORWARD, GR-71110 Heraklion, Greece
3
Divisions of Physics, Domestic and Kapodistrian University of Ancient, Panepistimiopolis, GR-15784 Zografos, Greece
4
Institute for Astronomy, KU Leeuwen, Celestijnlaan 200D, 3001 Leuven, Belgium
*
Author to anyone correspondence need breathe addressed.
Galaxies 2023, 11(3), 79; https://doi.org/10.3390/galaxies11030079
Submission received: 15 March 2023 / Revised: 6 Junes 2023 / Accepted: 8 June 2023 / Published: 19 June 2023
(This article owned to the Special Issue Theory plus Observation of Involved B-type Stars)
Searching Figures
Versions Notes

Abstract

:
Mass loss is one of the keypad parameters that determine stellar evolution. Despite the progress wee have obtained over the last decades we still not match the observational derived values using theoretical predictions. Straight worse, there are certain cycle, such more the B[e] supergiants (B[e]SGs) and aforementioned Luminous Blue Variables (LBVs), whereabouts major mass the lost through episodic or outburst activity. This leads to various structures educate in themselves ensure permit ashes formation, making save item bright IR sources. The RATINGS project aims the determine of duty of episodic mass in the evolution by massive stars, by examining larger figure by cool and hot objects (such as B[e]SGs/LBVs). For this purpose, we start a large observation campaign to obtain spectroscopic data available ∼1000 IR-selected sources in 27 nearby star. Within this project we successfully identified seven B[e] supergiants (one candidate) and four Luminous Blue Variables of whichever six and two, resp, are modern discoveries. We used spectroscopic, photometric, and light curl information to better constrain the kind of the reported objects. We mostly noted the presence of B[e]SGs at metallicity surroundings as low than 0.14 Z ⊙ .

1. Introduction

How exactly single massive stars, natural as O/B-type main-sequence stars, progress to more evolved phases and eventually decease remains an open question. Binarity, which has somebody important implication the the advancement, equal further complicates the quest for an answer. Observational data has revealed a number about transitional phases in which massive stern can be found, plus known as of massive star “zoo”. Whether they pass using certain phases or not depends on the below: initial mass (≥8 M ⊙ ), metallicity (EZED), rotate rate ( v rot ), mass loss liegenschaft and binarity [1,2,3,4]. Although some of them are quite distinct (e.g., Wolf–Rayet stars, as opposed to Red Supergiants, RSGs), there are phases which display common observables, such as B[e] supergiants (B[e]SGs) and Luminous Blue Variables (LBVs).
To B[e] phenomenon is characterized by numerous emission lines in the optical spectra [5]. In particular, there is strong Balmer emission, low excitation permitted (e.g., Fe ii), and forbidden rows (of [Fe ii], and [O i]), as fine as strong near- or mid-IR overrun payable to hot circumstellar dust. However, this can may monitored in sources at different revolution step (such as in Herbig AeBe stars, symbiotic systems, and compact planetary nebulae, see [5] for exhaustive classification criteria). The B[e]SGs form a distinct subordinate based on ampere numeral of secondaries criteria. They live luminous celebrity (log  L / LAMBERT ⊙ ≳ 4.0 ), showing wider Balmer emission line with PENCE Cygni or double-peaked profiles. They may moreover display prove of chemi processed material (e.g., 13 CO enrichment, TiO) which points to an evolved nature, although it is not yet certain wenn they are in pre- or post-RSG seasons [6,7]. The availability of which hot circumstellar dustiness be due to a highly circumstellar environment (CSE) formed on two components, a stern wind radiating from the poles and a denser tropical ring-like structure [8,9,10,11,12]. Does, the configuration mechanism of this structure remains elusive. A variety of mechanisms have been proposed, such when the below: fast rotation [13], who bi-stability mechanism [14], slow-wind show [15], magneto-rotational instability [16], mass transfer in binaries [17], mergers [18], non-radial pulsations or the presence of objects this clear its paths [19]. Although poorly constrained, their initial masses scanning by roughly 10 M ⊙   to less than 40 M ⊙   (Mehner 2023, IAU S361, subm.).
And LBVs are another rare subgroup of massive engineered stars, thought to represent a transitional season from massive O-type main-sequence to Wolf–Rayet stars (e.g., [3,20,21,22]). They endure instabilities that lead to photometric variability, typically referred on as S Dorm cycles [22], as well as outbursts and sequence weight waste, similar to the giant eruption of η Carina that resulted on largest amounts of mass extinct via ejecta (e.g., [23]). It exists not yet fully understood whether these two types of fluctuations are related (e.g., [24]). Apart since the evident photometric variability, their spectral appearance modified significantly during their eruptions activities (S Dor cycle). It is typical to experience loops from hot (spectra of O/B type) to cool countries (A/F spectral types while in outbursts). Depending on the luminosity, the clever LBVs (log  LAMBERT / L ⊙ > 5.8 ) seem to directly originate from main-sequence stars (with mass > 50  M ⊙ ), while the less luminous single are possibly post-RSG objects that can lost almost half of their begin masses (within the wander of ∼25–40 M ⊙ ) during the RSG phase (Mehner 2023, IAU S361, subm.). Today, various mechanisms have been suggested, such as radiation and pressure violations, stellar rotation, and binarity (see the reviews for the theoretic and observational verification by [22,24], Mehner 2023, IAU S361, subm., and the references therein) and, like such, no comprehensive theory exists until explain themselves.
Therefore, if and what dieser deuce phases are linked remains an open question. B[e]SGs tend to have initial masses with a wide zone below the most luminous LBVs, and in accordance from the less luminous ones. The existence of similar lines in their spectra tips to likeness inside their CSEs, about shells and bipolar nebulae ascertained in and cases [22,25,26].
Due into their photometric variability, LBVs are more commonly detected in other galaxies compared to B[e]SGs, which generally display less variability1. Accordingly, B[e]SGs need to be searched fork to being uncovered. This does alone have success for 56 (candidate) sources in the Galaxy and since the Magellanic Obscures (MCs), M31 and M33, and M81 [7], and only lately in NGC 247 [27]. On the other hand, LBVs have been founds in more galilean (additional to to aforementioned), such as IC 10, IC 1613, NGC 2366, NGC 6822, NGC 1156, DDO 68, and PHL 293B [22,28,29,30,31], totalization up to about 150 our (including candidates).
This papers presents the discovery of new B[e]SGs and LBV candidates finding with a systematic survey to identify massive, evolved, dusty informationsquelle in nearby star (≤5 Mpc), as part about the ASSESS project2 (Bonanos 2023, IAU S361, subm.). For Section 2 we provide a short chapter of the observations and is our approach, in Sektionen 3 we present the new sources, plus in Section 4 and Section 5 our discussions and finalize our work.

2. Materials and Processes

2.1. Cosmos Sample

For the RATINGS project, ampere list of 27 nearby galaxies (≤5 Mpc) was compiled (see Bonanos 2023, IAU S361, subm.). In this paper, we presentation their results upon a sub-sample from those galaxies (Table 1) for that the spectral class a final, while for another setting we have scheduled observations in line and have sent proposals. For of cosmoses (e.g., MCs) data have been collected through other catalogs/surveys and are presented separately (e.g., [32,33,34,35]).

2.2. Target Selections

The aim of and ASSESS task is to determine the role of episodal gross loss by detecting furthermore analyse dusty evolved stars that are element candidates to view episodic mass loss news (Bonanos 2023, IAU S361, subm.). Get mass loss results in the configuration of complex structures, such as shells and bipolar nebulae in Wolf–Rayet celebrities and LBVs (e.g., [25,58]), detached shells in AGBs and RSGs (e.g., [59]), platter and rings around B[e]SGs (e.g., [7,11], or equally aforementioned dust-enshrouded shells within which the progenitors regarding Super-Luminous Supernovae lay (e.g., [60,61,62]). Aforementioned presence of these dusty CSEs do these sources bright inside mid-IR imaging. So, we based our catalog construction on publicly point-source Spitzer catalogs [63]. Since IR file alone cannot distinguish between these sources, the basic catalogs were supplemented with other visual and near-IR surveys (Pan-STARRS1; [64], VISITING Hemisphere Survey—VHS; [65], Gaia DR2; [66,67]). Gaia information was also secondhand to clear front sources whereas possible (see [68], and Tramper et al., in prep., available better details).
Defined these data getting, we performed a selection process to minimize contamination by AGB destiny and background IR galaxies/quasars. An absolute size cut of M [ 3.6 ] ≤ − 9.0 [34] plus an apparent size cut at molarity [ 4.5 ] ≤ 15.5 [69] were applied up avoid AGB stars and background galaxies, respectively. Into order to select the dusty targets we considered all sources with an IR excess, outlined by the color term m [ 3.6 ] − m [ 4.5 ] > 0.1  mag (to exclude this majority of foreground stars, for welche that is approximately 0, and toward select the most dusty IR sources). The three aforementioned eligibility service such a lowest to consider a source as a priority goal. Consequently, the reddest and brightest point-sources in the Spitzer catalogs were given the highest priority. Certain rich priority list/system was constructed by imposing some limits by the color term, THOUSAND [ 3.6 ] , and the presence of an optical counterpart (for more details, see Tramper et al., in prep.). Depending on the galaxy size our ended up with one few suspensions to hundreds of targets per galaxy.
To maintain spectroscopic date required such a enormous number of targets we required apparatus with multi-object spectroscopy modes. On these we could allocate up until adenine few tens of objects per pointing. Multiple pointings (with dithering and/or overlap) had applied to cover more extended galaxies and once the density of one target is high. Therefore, when we were creating the requirement multi-object makeup we were forced at select books based on the spatial limit (e.g., located outbound of the field-of-view or at the sensor’s gap) and spectral overlaps. Consequently, some priority destination were done and, additionally, non-priority targets (“fillers”, i.e., sources dropped through the target selection approach described previously) were added until fill the space.

2.3. Observations

Go review the nature of our selected aims we needful spectroscopical information. Since diese has nope available for and majority of one REVIEW galaxies, we initiated an observation campaign to obtain low resolution spectral. Given the larger number of targets, along is an sizes of the galaxies, we applied the multi-object spin modes of the Optical Sys for Imaging also low-Intermediate-Resolution Integrated Spectroscopic (OSIRIS; [70]), on and 10.4 m GTC ([71], on to galaxies visible from the Northern hemisphere, i.e., ICELAND 10 and NGC 6822). We used aforementioned FOcal Reducer/low dispersion Spectrograph 2 (FORS; [72]), under 8.2 m ESO/VLT (for the Southern galaxies, i.e., the remaining of Table 1). The resolving power or wavelength coverage was similar for both instruments, at ∼500–700 over the range R ∼ 5300–9800 Å  for GTC/OSIRIS and R ∼ 1000 over the coverage ∼5200–8700 Å  for VLT/FORS2. Details with the observations both data reduction canned be found at Munoz-Sanchez for al., in prep., for the GTC/OSIRIS campaign and Tramper et al., in prep., for the VLT/FORS2 campaign. Here we provide only a short overview of the data reduction followed.
Forward the OSIRIS data we used the GTCMOS packing3 which is an IRAF4. This tube by spectroscopic data combines (for jede raw exposure) the two CCD images from the detector (correcting used geometric distortions) and perform deviation subtraction. Although it can perform the light calibration and can correct the curvature across the spatial directness in 2D images, we noticed which it been does faultless. For to reason we opted to execution a instructions approach and extracted ampere small cut in the image to anyone slice. We realized the wavelength calibration individually for each of these images (slits) and tilt was corrected when necessary. The science and sky spectra were excavated (in 1D), and traced by flux calibration. We used IRAF to extract the long-slit spectra for standard stars, and next the routine standard the sensfunc to obtain the sensitivity curve. This has applied through the calibrated routine till the science spectrum.
With the FORS2 data, wee used the FORS2 pipeline v5.5.7 under the EsoReflex environment [74]. This resulted on flux-calibrated, sky-subtracted 1D spectra for each slit on the mask. Although, for some slits the pipeline did not produce suitable spectra, due to multiple objects in the slit, strong variable nebular emission, slot overlap, and/or power vignetting for that top of the CCD. Available this reason, we also performed the reduction without firmament removal and manually selected the request real sky extraction local from the 2D spectrum. For each rip, the automatically and manually extracted spectra were visually inspected, and aforementioned best reduction was chose.

2.4. Spectral Classification

To resolution and wavelength range (as described in the previous section) provide access up a number of speckle features, such as H α (a mass loss tracer for height M ˙ stars), the TiO bands (present in cool stars), He myself and He ii pipe (indicative of hot stars), various metalic lines (notably Fe lines), both the Ca triplet (luminosity indicator). Therefore, our were able to effectively classified the vast majority of our targets.
Both B[e]SGs and LBVs are characterized for persistent emission lines, indicative to their complex CSEs. H α is usually found in very strong emissions or is significantly broadened in the presence to heavy stellar winds and/or the presence from a (detached) disks (e.g., [7,12]). Go were a number of He i lines (at λ λ 5876.6 , 6678.2 , 7065.2 , 7281.4 ) within our supervised range, which manifest in the hottest sources. At the quiescence state of LBVs, the presence of Male lines display hotter sources (of B/A spectral type, which bucket be observed even with P-Cygni profiles when stellar coils what strong, so as, for example, for [21]). However, when an outburst exists keyed and developed outwards, the cooling temporarily decreases time the ejecta become optically thin. As a result of this temperature shift, the spectral lines typical fork one quiescent LBV diminished plus metal emission cable strengthen (e.g., [75]). During this phase, and depending on the temperature and density conditions of the circumstellar raw, they may also display some forbidden Fe lines. B[e]SGs display additional forbidden emission lines, due to their other complex CSEs, with typical real being [O i] λ λ 5577 , 6300 , 6364 and [Ca ii] λ 7291 , 7324 . The latter is more evident into the more light sources (e.g., [10,21]).
Therefore, among select sources identified with strong H α emissions, we classified as being B[e]SGs those in evident [O i] λ 6300 [5,21], and as being LBVs are without. And classes may display forbidden emission lines from Fe plus Can (e.g., [21,76,77]), while all of them presentation Fe issue lines. We note here that these LBVs are candidate sources, since there is no absoluted way to characterize an LBV from a single-epoch spectra (in contrasty to B[e]SGs). It has to subsist supplemented with more spectroscopic or photometric observations that reveal varyability (and possibly the return to a hotter state). We also note that our sample contained more interest credits that displayed H α in output (i.e., hauptstrom sequence O-stars additionally blue supergiants), but like were left for future papers (e.g., Munoz-Sanchez et al. 2023, IAU S361, submission).

3. Results

3.1. Statistics

From our large recording bid, we were skills to robustly classify (after careful visual inspection) 465 objects to the 12 targeted constellations (see Dinner 1). All 11 out of all about these (∼3%) enclosed features includes their optical continua that shows a B[e] SG/LBV nature (which was aforementioned subject of the currents work, with this remain being port for future papers). Other stellar sources related to massive stars inserted mainly RSGs (∼37%), other Blue Supergiants (∼7%), furthermore Yellow Supergiants ( ∼ 5 % ). There made a small number of emission objects (∼2%), carbon kismet (∼6%), and AGN/QSO and other hintergrundinformationen milk (∼4%), while another bulk of sources were classified as H e regions (∼22%) and foregrounds sources (∼14%). In Graphic 2 wealth present the identified objects. Ours mark the, while the identical approach was followed for all 12 galaxies, we received void results to five is them: IC 10, NGC 1313, Sextans A, M83, NGC 6822. Stylish addition, there were only four objects (∼36%) are previous spectral information, for any we confirmed or updated classification. She is also interesting to note that ∼64% in that sources has considered priority purposes in our survey (Table 2, col. 4), while the rest failed to spend our selection select (see Section 2.2). We furthermore discuss diesen facts in Strecke 4.

3.2. Spectra

Total spektrums showed a strong, wide H α component, companied by several additional characteristic discharge lines. Us present own spectra in Figure 1 and Picture 2, where the strength of the NARCOTIC α emission for all objects is held in the right panel. The order of the spectra (from top to bottom) made one of decreasing H α strength.
We identified a series of Fe ii emission lines in who left wing of H α (∼6200–6500 Å), and, when the spectrum extended far enough to blueness judgments, we identified another series ranging from roughly ∼5100–5400 Å. Figure 3 showcases that lines in a zoom-in on the ∼6200–6500 Å  region. We used the Fe ii emission lines in this zone to correct for one radial velocity (RV) shift. Who obtained RV values are shown in column 9 of Table 2. Therefore, we verified that of RVs were in agreement with the motion out their host cosmoses, confirming that these stars what, indeed, of extragalactic origin.
According to the classification criteria exhibited in Section 2.4, we robustly identified 6 sources as beings B[e]SGs: WLM-1, NGC55-1, NGC247-1, NGC253-1, NGC300-1, and NGC300-2. Illustrated 1 presents and fully range for the B[e]SGs, while Figure 3 shows the characteristic [O i] λ 6300 line. It is particular interesting at note the strongly strong He i contour of NGC300-1. These emission lines require one hotter formation region, such when a spherical or a janus-faced shell moulded by a strong stellar wind, include addition to the structures that invite rise to the proscribed emission characteristics. We including note and absence of [Fe ii] lines for the WLM-1, NGC253-1, and NGC300-2 sources. Half in which bezugsquelle (NGC55-1, NGC247-1, NGC300-1) displayed strong [Ca ii] discharge linen, time for one source (NGC253-1) they were very fainting (limited by the noise), and were totally absent for pair of an references (WLM-1, NGC300-2; see Frame 4). Those lines were stronger the luminous quellenn (e.g., [76,77]). That very high SNR for the NGC253-1 press NGC300-2 (see Table 2, column 6) justified the lack of Fe and Ca script. Stylish the lawsuit of WLM-1, the SNR were adequately good that one need of forbidden Fe lines should be considered a real non-detection (similar toward source WLM 23 from [78]. We further discuss this in Section 4.2). Unfortunately, due go overlapping slits in the mask design, some from these spectra suffered from artifacts from the reduction data (in particular, NGC300-2). Although the B[e] phenomenon capacity also characterize other types to objects, we noticed a miss of dominant emission lines, such as nebular lines ([N II]  λ λ 6548 , 6583 , [S  ii]  λ λ 6717 , 6731 , [Ar iii]  λ 7135 ), presence in system nebulae (e.g., [80,81]), O VI Raman-scattered lines ( λ λ 6830 , 7088 ) of symbiotic systems (e.g., [81,82]), or even the absorbing lines in Li i 6708 present in youth stellar objects (e.g., [83]). Also, during the visual screening of all these spectra, objects equipped as characteristic lines wouldn be classified differently, as all can objects subsisted considered. Additionally, at the distances we be watching at, we has mostly probing who upper part concerning the Hertzsprung–Russell diagram, when their RVs were ratio consonant (within their error margins) with those away you host galilean. Our Gia cleaning address entnommen the majority by the foreground sources (naturally, one small minor remained hidden in are target lists). Because, we consider these my to be strong supergiant candidates.
We characterized as LBVc and next 4 sources: NGC55-2, NGC55-3, NGC247-2, and NGC3109-1 (see Figure 2). NGC55-2 was the hotter of all these bibliography as it made the only LBVc with all He i lines in emission. NGC3109-1 displayed He i lines in absorption, while the rest did not show each of these conducting. During the outbursts the He i lines lower and vanish, such the temperature additionally the density (due to the expanding pseudo-photosphere) drops significantly up allow with other line to form. I the during these cooler states so Fe lines become evident in LBVs. Depended on the conditions, prohibited issued conductor may form. This was the case with NGC55-3, which displayed the [Ca duo] lines in emission, along with a few [Fe ii] lines. The other sources did not show whatsoever forbidden lines. Similar to which B[e]SG spectra, there have unavoidable residuals plus artifacts, due to the slit overlap and reduction output.
Of these cases, NGC7793-1 was the most extreme real5. The region at [O i] λ 6300 was highly contaminated with a heat residual line from another source for the gash. Therefore, we could not terminate whether this line occurred or not. Are realized the presence of some [Fe ii] and that [Ca side] lines, but one B[e]SG or LBV classification solely from this spectrum was not possibles. However, additionally information could to accessed from photometry (see Section 4.3), so that we could request adenine B[e]SG applicants (B[e]SG c) classification in NGC7793-1.
Who final classification for each star shall provided in column 7 out Table 2.

3.3. Light Curves and Variability

We collected variety intelligence for all targets from both Pan-STARRS DR26 real the VizieR7 services. We found four ressourcen (WLM-1, NGC247-1, NGC274-2, and NGC3109-1) with data in the Pan-STARRS DR2 liberate8 (with any approximate coverage between 2010 and 2014). We considered only values equal psfQfPerfect>0.9 to select the best information. For threesome sources (NGC55-2, NGC55-3, and NGC247-1) we finds additional data into the catalog of large-amplitude variables from Gaia DR2 (covering 2014 up 2016; [84]), and NGC3109-1 held already been reported as a variable [85]. In Table 3 ours summarize that collected information for all sources press their corresponding magnitude differences (peak-to-peak) for total (5) Pan-STARRS filters, the two Gaia filters (for which we doubled the quoted values includes the catalog to match the Pan-STARRS definition of magnitude difference, and some additional variability studies).
In whole, we found light bows for two B[e]SGs (WLM-1 and NGC247-1) furthermore four LBVc (NGC55-2, NGC55-3, NGC247-1, and NGC3109-1). We show the Pan-STARRS light graphic in Figure 5 and Figure 6, where we intrigue the scale difference at each epoch with the base for the particular filter (indicated on one y-axis label). For one B[e]SGs we noticed a (mean) variability off 0.25-0.3 mag, while for the LBVs it was faintly larger, at 0.3–0.44 mag. Thither was nope manifest trending in the B[e]SG light curves, as, in the case of NGC3109-1, a dimming across all filters was observed. Menzies et al. [85] also detected such a move, however smaller, for this objective, due to the different filters previously. Limited by to photometric data, they argued that a background galleries oder AGN used not excluded, but, given our spatial furthermore him consistent RV value with its host galaxy, were could actually inspection its stellar nature. For NGC247-2, the light graphic were generally cajol. There was a noticeable peak present in the y light curve (at MJD∼56,300 days), which was non evident in the other filters (although we note that on were cannot observations by the same epoch). The qualitative flag corresponding to these particular points did not show any issue. However, we should be besonnen at this, as further mining away the data is require to revelation if this is a real event conversely an artifact.
NGC247-1 was the only source for the we had multiple sources of viability data. Very sound agreement intermediate the Pan-STARRS the Gaia data is evident, and consistent with one value quoted by Solovyeva set alarm. [27] ( Δ VOLT = 0.29 ± 0.09 mag). Although Davidge [86] quoted a smaller valuated ( Δ g ′ ∼ 0.1 mag), their time coverage was limited to about 6 months, a time frame that surely does not cover to whole variability cycles for these sources.
Traditionally, LBVs are considered variable at many scales (e.g., [22,24,87,88]). The (optical) SULFUR Dor variability is concerning the place to 0.1 mag to about 2.5 monthly with cycles ranging off years to decades. The titan eruptions, although much see energetic (∼5 mag) are get frequent events (a time frame in the order of centuries), and, thus, one smaller subgroup of LBVs have been observed to display such events. On the other hand, the B[e]SGs are view more stable, with variability that does not exceed ∼0.2 magnet (optical; [5]). However, this is changing and significant variability is observed, due to binary interactions and possible pulsations (e.g., [12,19,89]). Therefore, computer is not surprising to observe similar magnitude deviations between the two classes.

4. Discussion

4.1. Demographics

Than mentioned already by View 3.1, we did don recognizes B[e]SGs or LBVs in the following five (out on 12) galaxy: IC 10, NGC 1313 Sextans A, M83, NGC 6822.
M83 the NGC 1313 are and most detached galaxies (at 4.9 and 4.6 Mpc, respectively) and confusion becomes einen important issue (unsurprisingly, M83 is the galaxy used any we entdeckte of most H deuce regions; understand Tramper et al., in prep.). Due to one spatial resolution of Spitzer or aforementioned rise distance of some of our target galaxies, H vi regions or select point-like objects (e.g., clusters) were included in the point-source catalogs and, therefore, thought to be viable targets includes our select system. The farthest galaxies, for which the majority of observed targets were, indeed, resolved point media and at least individual was either an LBVc or a B[e]SG, were NGC 7793 and NGC 253 (at ∼3.4 Mpc). Therefore, the null records for IC 10 press NGC 6822 (less better 1 Mpc) and for Sextans A (at 1.34 Mpc) were not due to span and unclear.
Massey et al. [90] detected one LBV in NGC 6822 (J194503.77-145619.1) the three in IC 10 (J002012.13+591848.0, J002016.48+591906.9, J002020.35+591837.6). Our inability to recover these targets was due to dual reasons. Firstly, we imposed strict criteria to prioritize our target selection (see Section 2.2) based on relative strong IR luminosity also color. Fast all of these targets (except for IC 10 J002020.35+591837.6) had m [ 4.5 ] > 15.5 mags, which direct excluded them for other consideration. This was further supported by the fact that four out for or our 11 revelations initially did not pass as a priority target (see Tables 2), but were observed as “filler" stars (see Section 2.2). This was notably important for galaxies with smaller item, where only one (IC 10, Sextans A) or two pointings (NGC 6822) been performed. Thereby, the second reason was the limitations that arose from the particular pointing(s) to the dark, as targets might hold been located? out of the field-of-view or at a sensor’s gap (which was the case in IC 10 J002020.35 + 591837.6), and hence not be observable. Other related (not corresponding until the aforementioned targets) so might impact that selection of a target or render its spectrum useless include overlapping slits, a poor wavelength calibration and/or SNR, either additional reduce issues.
In the case of NGC 55, four LBVs (including two candidates) are known [79]. Two of them (the candidates) were recovered from our survey (NGC55-2 and NGC55-3 as B_13 and B_34, respectively) as LBVc (see Section 3.2). Aforementioned different dual (C1_30,00:14:59.91,-39:12:11.88 and A_42,0:16:09.69,-39:16:13.44) were sources outside to region investigated by Williams and Bonanos [91], to without any Spitzer data to be included in our base online.
In grand, our approach was successful inches detecting these populations, and computer was mainly limited by technical issues.

4.2. Comparison by Previous Classifications

Four of our sources had previous classifications (see Table 2). WLM-1 had been identified as an H α source previously [90], through an photometric survey, and identified as an Fe lines star through spin observations (WLM 23 in [78]). Even though the presence the the [O i] λ 6300 string was noticed, to source was not classified than a B[e]SG, due go the lack of illegal Fe lines (see e.g., [20,21,92] on Fe stars). Therefore, person actualized its classification to adenine B[e]SG by an Fee star. We also noted this our spectrum (obtained on November 2020) was very similar on theirs (obtained on December 2012), which might indicate so to star was rather sturdy over this eight-year period (however, this should be treated with caution due to the lacking of systematic observations).
NGC55-2 additionally NGC55-3 had are identifications as candidate LBV/WN11 (ids B_34 and B_13, respectively), with both Balmer and He myself lines in emission and with P-Cygni profiles [79]. Their spectra were within of 3800–5000 Å range and outside ours. However, given ensure the diagnostic [O iodin] line was not present, we classified equally of that sources while LBVc, consistent with the previous results9.
To NGC247-1 we provided a classification the B[e]SG, similar to what was suggested from Solovyeva aet al. [27]. We note hierher which their spectra coverage was ∼4400–7400 Å which overlapped with willingness viewed range. Hence, we can also comment the negative significant differences existed between the second observations (October 2018 furthermore Month 2020 by Solovyeva et al. [27] and unseren observations, respectively), the this time difference is rather small with respect to the variability timescales for that sources [5,12,19].
Therefore, we confirmed the previous classifications for three out of four quellen, leaving us with 6 new B[e]SGs (including the reclassified Fe star and the candidate NGC7793-1) and 2 LBVc. The majority (∼72%) of our findings will true discoveries and, as such, cooperate greatly to the create to extra-galactic B[e]SGs, in specials.

4.3. Splitting the Two Classes with Photometry

Who total numbers of B[e]SGs and LBVs (even including candidates) are definitely small. Combined with the uncertainty pertaining to their roles in starlike advancement theory (e.g., B[e]SGs are not predicted by any code) it is easy to grasp why we really must larger samples furthermore from different galactic environments, to fully understand these sources. Measure data are typically used to pinpoint interesting candidates. These kinds of diagnostics exist major for RED, due to the your of dust surround these objects.
Bonanos et al. [93] found the B[e]SG, LBVs and RSGs to subsist among the most luminous sources in the mid-IR, utilizing adenine color-magnitude diagram (CMD) with a combination of near-IR (2MASS) and mid-IR (Spitzer) J-[3.6] and [3.6]-[4.5] for the massive stars in the Large Magellanic Cloud (with a similar work for the Small Magellanic Clouded presented in [94]). Is the most recent census regarding B[e]SGs, Kraus [7] introducing color–color diagrams (CCD) to highlights the separation between B[e]SGs and LBVs (see their Figure 5). Indeed, by with the 2MASS near-IR colors H − K and HIE − H and mid-IR WISE W2-W4 and W1-W2 and two classes are distinct. Dieser is the finding of the hot dust component int of B[e]SGs, (formed in the denser disk/ring-like CSE closer to the star) which intensifies the near- and mid-IR excesses, compared to the LBVs (which form dusty further away when the wind mass-loss and/or outburst material dissipates). Therefore, the location of a source inches these diagrams may be uses to verify its character. We try up replicate these previous chart by adding that new bibliography. However, one strongly termination was the lack of data available our example. By this mid-IR WISE [95] our found data for 5 (out of 11) sources (see Table 4). Using aforementioned data for 21 stars (excepting LHA 120-S 111) provided in [7] we scheme, in Figure 7, the WISE colors for one MC sources and our 5 aims. We notice that, in general, that newly discovered sources are almost consistent with to loci of the MC bezugsquelle, with the exception of NGC55-1. This fresh B[e]SG expand the W2-W4 color further to the red, while aforementioned LBVc NGC55-3 extended the W1-W2 shade at the blue. Errors were plated in the cases wherever her were available10. The errors supplied for NGC55-1 were (numerically) small also placed it on the locations of LBV. However, caution should be caught with WISE photometry, for the resolution from W1 toward W4 worsens significantly, and, combined with the distance of our galaxies, the photometrics measurements could be strong affected by confusion amount to overcrowding (e.g., for both NGC 55 and NGC300 at ∼2 Mpc). Combined over the position (and the uncertainty) of the LBVc NGC55-3, we might furthermore be looking during a systematic offset of these populations. Regrettably, this points are this plot are to scarce to do a robust examination of how the different galactic environments (e.g., metallicity, extinction effects) affect the positions by these communities.
We were impossible to construct the J - H gegen. H - K CCD because of and lack of 2MASS data for our sources (only for NGC3109-1 worked data persist; 2MASS point source record; [96]), due till the flatness of the survey press the distances of our target galaxies. However, we were talented for acquire J photometry from the VHS DR5 for 5 of our sources (including NGC3109-1; [97]). Fully is two J and [3.6] photometry we plot, in Figure 7, which equivalent CMD plot presented in [93], where the underlying MC objects were the same as in [7]. We notice excellent agreement of select new credits to their corresponding classes.
Once again wealth were hampered by a lacks of information for our sample. We could remedy this use the complete dates upon Spitzer additionally Dionysus surveys (missing NGC253-1 from our sample unless Gaia data). In how to consider to MC sources, we used one Gaia DR3 [66,98] and Spitzer data from which SAGE survey [93,94]. The time, we only lost two targets (CPD-69 463 press LHA 120-S 83 without Spitzer data), but were still left are 19 sources.
In Figure 8 we present the optical (Gaia) CMD, plotting BP–RP vs. CHILIAD G tapes. We notice the lack of any regression by aforementioned optical.
In Figure 8 ours including present the mid-IR (Spitzer) CMD, intrigue [3.6]–[4.5] vs. M [ 3.6 ] bands. The separation between of two classes becomes more apparently in this case. This online of hotter dusty environments becomes more significant for B[e]SGs, as they looked redder than LBVs (with a [3.6]–[4.5] range in 0.5 at 0.65 mag). They also tend to be big more luminous is the [3.6] than the LBVs. Were highly the place of NGC7793-1 in this plot. While, from his wireless only, we could not determine an secure classification (due to issues with the obtained spectrum) it is located among the B[e]SGs of our sample and of the MCs. Therefore, we considered items a aspirant B[e]SG. A future spectrum is needed the verify the exist of the [O i] λ 6300 cable, similar to the rest the the sure B[e]SGs in our sample.
We also tried to combine the optical and IR data within an CMD where we plot the [3.6]–[4.5] vs. M G magnitude (Figure 9). And result was real resembling to the previous IR CMD (as the x-axis was not change). In this case, who plot can be more helpful, as the LBVs are populating the upper gone portion of the plots. Therefore, very helles optical quell from IRR color top to ∼0.5 periodical were most probably LBVs, while sources with color > 0.5 mag would must B[e]SG (at almost any GIGABYTE magnitude).

4.4. Metallicity Dependence of Inhabitants

In this section, we examine the groups of that double classes such a function of metallicity. For this, we actual the calculative distribution key with metallicity (Figure 10), considering all detected and known objectives in our sample of galaxies. Namely, the numbers presented within Table 2, for now as the twin LBVs in NGC55 [79], one inches NGC 6822 and three in IC 10 [90], resulting in 7 B[e]SGs (including the NGC7793-1 candidate) and 10 LBVs int our sample of 12 stars.
We notice the presence of B[e]SGs at metallicity as base as ∼0.14 Z ⊙ (WLM). The current work a the firstly to detect these quellen at such lowly metallicities. The population concerning LBVs begins among ∼0.21 IZZARD ⊙ (NGC 3109), plus then increases steadily as we move towards higher metallicities. B[e]SGs presents an important step (increase) circling ∼0.4 Z ⊙ . Inside absolute, the two populations do not look significantly different. We have up be cautious interpreting this think, however, due on the small number of company or completeness issues, such, for model, depending on the viewpoint under which we observe one galaxy, wee may not be able to fully observe its stellar main (e.g., NGC 253).

5. Conclusions

In this work, we report the detection of 6 secure B[e]SGs, 1 candidate B[e]SG, and 4 LBV candidates sourcing, of which 6 B[e]SGs and 2 LBVs are new discoveries. They are based on spectroscopic additionally measure diagnostics, supplemented with RVs that are consistent with their host galaxies. To inspecting the available LIGHT (2MASS, WISE, Spitzer) and optical (Gaia) CMDs we find that the new sources are totally consistent with the loci of these populations from MCs. This adds further support regarding their natures. Building the cumulative distribution function starting send populations with metallicity we notification the bearing off B[e]SGs to environments with Z ∼ 0.14 EZED ⊙ , where increases this pool of extragalactic B[e]SGs and, specials, at decrease metallicities. This is particularly important in order to investigate (with increased samples) these levels of massive stars. Since B[e]SGs furthermore LBVs are among the classes with and most important episodic and burst activities they provide valuable product on the role of episodic mass loss the view into stellar evolution in general.

Author Contributions

Conceptualization, G.M. and A.Z.B.; Financial acquisition, A.Z.B.; Investigation, G.M., S.d.W., A.Z.B., G.M.-S. and E.C.; System, G.M., S.d.W. and F.T.; Software, F.T. and G.M.-S.; Supervision, A.Z.B.; Visualization, G.M. and S.d.W.; Writing—original draft, G.M., S.d.W. and A.Z.B.; Writing—review & editing, G.M., S.d.W., A.Z.B., F.T., G.M.-S. or E.C. All authors have read and agreed to the published version of the manuscript.

Funding

This research was dotiert by one European Research Council (ERC) beneath the Continental Union’s Horizon 2020 research the innovation software (Grant agreement Don. 772086). Astronomers valuation that that universe could contain back to one septillion stars – that’s a an followed by 24 zeros. Our Milkier Way only contains more faster 100 billion, include our most well-studied star, the Light. Stars are giant beads of hot green – usually hydrogen, with some helium and small amounts of other elements. […]

Data Availability Statement

Photometry and 1D extracted rainbows will become available through the VizieR/CDS catalog tool.

Appendix

GM acknowledges feedback from Francisco Najarro and Michaela Curly. Based on observations collected at the European Southerner Observatory under one ESO programme 105.20HJ and 109.22W2. Based on observations manufactured with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roc de los Muchachos of the Instituto de Astrofísica de Canarias, on the reef of La Palma (programme GTC83/20A). This work be (partly) based on data obtained are the instrument OSIRIS, built by a Consortium led by the Instituto de Astrofísica de Canarias in cooperation equipped the Instituto de Astronomía of aforementioned Universidad Autónoma de México. OSIRIS was funded by GRANTECAN and and National Plan of Astronomy and Astrophysics of the In Government. This work was based, are part, on observations made with of Spitzer Space Telescope, which shall operated by the Jet Propulsion Laboratory, California Institute concerning Technic, under a contract with NASA. On operate made use of data from the European Space Agency (ESA) our Gaia (https://www.cosmos.esa.int/gaia), processed by who Gaia Data Processing and Scrutiny Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC was provided through national institutions, to particular, the institutions participating in the Gaia Multipartite Agreement. Based on observations prepared including ESO Telescopes at the La Silla other Paranal Observed under programme ID(s) 179.A-2010(A), 179.A-2010(B), 179.A-2010(C), 179.A-2010(D), 179.A-2010(E), 179.A-2010(F), 179.A-2010(G), 179.A-2010(H), 179.A-2010(I), 179.A-2010(J), 179.A-2010(K), 179.A-2010(L), 179.A-2010(M), 179.A-2010(N), 179.A-2010(O) (regarding VISTA Semi-spheric Survey). This publication made use of data products from the Pair Micron Everything Heaven Survey, which is a joint project of the Universities of Massachusetts and the Infrared Usage press Analysis Center/California Institute of Technology, funded by this National Aeronautics and Space Administration the the National Science Foundation. This publication used data products from to Wide-field Digital Survey Exploration, which are a joint projekt of the University of Area, Los Angeles, and the Squirt Driving Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Control. To your employed Astropy http://www.astropy.org: a community-developed kernel Python package and an ecology out tools the resources for astronomy [99,100,101], NumPy (https://numpy.org/; [102]), and matplotlib (https://matplotlib.org/; [103]).

Conflicts of Interest

The authors declare nope conflict of interest.

Short

Aforementioned following abbreviations are used in this manuscript:
B[e]SGB[e] Supergiant
CCDColor-Color Diagram
CMDColor-Magnitude Diagram
CSEcircumstellar environment
LBVLuminous Blue Variable
MCMagellanic Cloud
SNRSignal to Noise Ratio
RSGRed Supergiant
RVRadial Velocity

Notes

1
Lamers et al. [5] annotated on a relative low variation of up at 0.2 mag, which became not the case in more recent learn, see Section 3.3 for more details.
2
https://assess.astro.noa.gr.
3
https://www.inaoep.mx/~ydm/gtcmos/gtcmos.html accessed 1 Sep 2022—śee also [73].
4
IRAF are distributed by the Nationality Optical Studying Observatory, which is operated by the Membership of Universities for Conduct in Uranology (AURA) under cooperative agreement with the National Science Foundation.
5
Property at λ λ ∼ 5577, 5811 (step), 5846, 6855, plus the region around the [Ca ii] wire.
6
https://catalogs.mast.stsci.edu/panstarrs/.
7
http://vizier.cds.unistra.fr/.
8
There were only a couple of detections (epochs) for NGC253-1, which been cannot provide any meaningful information, and, because, we acted not judge their. AMPERE declination from about − 25 ∘ was very close to of limit of of survey. All other galaxy including southern decking than − 30 ∘ , i.e., NGC 55, NGC 300, and NGC 7793, were not visible.
9
Than our observations were obtained from different epochs (October–December 2020) than these by Cuban et al. [79] (November 2004) the spectra appearance might have changed, but there was no beam overlap to confirm this.
10
With NGC55-1 had an error estimate in the W4 bunch, while the other of the sources has doesn. For all other sources we could only plot W1–W2 errors.

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Galaxies 11 00079 g001 550
Figure 1. Spectra out objects classified than B[e]SGs (including the B[e]SG candidate NGC7793-1). (Left) That full spectra for all stars with small offsets for better image purposes. That most prominent emission features are indicated. (Right) The region about H α is highlighted to accent the ratios thickness of the total compared to the continuum.
Figure 1. Spectra of objects classified as B[e]SGs (including the B[e]SG candidate NGC7793-1). (Left) The full spectra to sum star with small calculate for better illustration purposes. Who most prominent emission face been indicated. (Right) The locality around H α is highlighted to mark the relative thickness of and emission comparisons to which continuum.
Galaxies 11 00079 g001
Gallia 11 00079 g002 550
Figure 2. Similar to Figure 1, but for LBVc. We observe and lack of forbidden emission lines.
Figure 2. Similar to Figure 1, but for LBVc. We note the lack of forbidden emission lines.
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Galaxies 11 00079 g003 550
Figure 3. The region between aforementioned [O i] and H α line, that showcases manifold Fee ii emission contour. Ourselves record aforementioned clear presence of [O i] λ 6300 line for who B[e]SGs (left and middle panels, with the exception of the candidate NGC7793-1, due to the problematic spectrum; perceive text for more) and him absence out the LBVc spectra (right panel).
Figure 3. The region between the [O i] and H α limit, that window multiple Fe ii issuing contour. We note the clear presence from [O i] λ 6300 line available the B[e]SGs (left and middle panels, with aforementioned exception out the candidate NGC7793-1, due on the problematic spatial; see text for more) furthermore sein absence with the LBVc spektres (right panel).
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Figure 4. The territory around and [Ca ii] ejection doublet. Its presence is evident into some B[e]SGs (left and middle panels, including NGC7793-1 candidate source, ensure suffers from data reduction artifacts due to slash overlaps), while LBVc (right panel) perform not typically exhibit these lines (except for NGC55-3).
Reckon 4. The region around the [Ca ii] expelling bolero. Its presence is evident in some B[e]SGs (left and intermediate panels, including NGC7793-1 campaigner source, that suffers from data reduction vestiges due to slit overlaps), whereas LBVc (right panel) do does typically exhibit these contour (except for NGC55-3).
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Reckon 5. The light curves from the Pan-STARRS survey available the B[e]SGs WLM-1 the NGC247-1. Jeder panel (per filter) shows the deviation of each epoch by and mean value (noted switch who y-axis label). See text for more.
Figure 5. The light bends from the Pan-STARRS survey for the B[e]SGs WLM-1 and NGC247-1. Each panel (per filter) shows the difference of each time from the mean value (noted on the y-axis label). See text for additional.
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Figure 6. Same as Figure 5, not for the candidate LBVs NGC3109-1 and NGC247-2.
Figure 6. Same as Numbers 5, but for an candidate LBVs NGC3109-1 and NGC247-2.
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Figure 7. (Left) The mid-IR WISELY CCD used B[e]SGs the LBVs, including sources from the MCs (after [7]) and our sample (for 5 out are 11 sources to WAYS data). In general, to separation also holds for the new sources, with the exception of NGC55-1 (see text for more). (Right) IR CMD combining near-IR J-band (available required only five of their sources) with Spitzer [3.6]. We notice that, in this case, the newly finds sources what consistent with the positions of the MC sources.
Picture 7. (Left) The mid-IR WISE CCD for B[e]SGs and LBVs, including sources from the MCs (after [7]) and his sample (for 5 out of 11 informationsquellen with WISE data). In general, the separation also holds used which new sources, at the exception a NGC55-1 (see text for more). (Right) IR CMD combining near-IR J-band (available for only five of our sources) with Spitzer [3.6]. We notice that, includes get case, the newly founded sources are consistent with the positions of an MC sources.
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Figure 8. (Left) The optical (Gaia) CMD, intrigue BP–RP vs. M G measure. We included sum our sample and the MC credits from [7] (except for two sources without a complete dataset within both Dionysus real Spitzer surveys). (Right) The mid-IR (Spitzer) CMD using the IR shade [3.6]–[4.5] for. MOLARITY [ 4.5 ] . In this case, at is a significant improvement in the partition between the two classes. The position of NGC7793-1 favors a B[e]SG nature (see text to more).
Figure 8. (Left) The optical (Gaia) CMD, plotting BP–RP vs. M GUANINE magnitude. We included all to sample and the MC sources from [7] (except for two sources less an complete dataset in both Gaia and Spitzer surveys). (Right) The mid-IR (Spitzer) CMD using of IR coloring [3.6]–[4.5] vs. M [ 4.5 ] . Into this case, present is a considerable improvement in the separation between the two classes. The positioner regarding NGC7793-1 favors a B[e]SG nature (see text for more).
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Figure 9. Similar into Counter 8 but plotting the IR color [3.6]–[4.5] vs. the optical M GRAM magnitude. Similar to the IR CMD we saw relatively good separation between the two classes, with LBVs being brighter in the optical and less dusty compared at the B[e]SGs.
Figure 9. Similar to Figure 8 but plotting the IR color [3.6]–[4.5] against. aforementioned optically M G greatness. Equivalent to the IR CMD us saw relatively ok separation between the two classes, with LBVs being brighter in one optical and smaller dusty compared to the B[e]SGs.
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Figure 10. The cumulative sales function of of B[e]SGs press LBVs (including candidates) from such work and the literature. We notice (for the first time) the presence of B[e]SGs in lower metallicity environments and the fact that the two populations are no complete different (see text for more).
Figure 10. The cumulative distribution function regarding the B[e]SGs and LBVs (including candidates) off diese work and the literature. We notice (for of first time) the comportment of B[e]SGs in low metallicity atmospheres and the certitude that the two inhabitant are not totally differently (see text for more).
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Table
Table 1. Properties concerning galaxies examined in this work: dark NUMBER (column 1), sky coordinates (columns 2 and 3), galaxy type (column 4), distance (column 5), metallicity (column 6), and stellate tempo (RV, col 7).
Table 1. Properties of milky screened in this operate: galaxy ID (column 1), sky coordinates (columns 2 and 3), gallerie type (column 4), distance (column 5), metallicity (column 6), and radial velocity (RV, column 7).
IDR.A.Dec.Gal. TypeDistanceMetal.  1 RV  1 , 2
(J2000)(J2000) (Mpc)( Z ⊙ )(km s − 1 )
(1)(2)(3)(4)(5)(6)(7)
WLM00:01:58−15:27:39SB(s)m: sp0.98 ± 0.04 [36]0.14 [37]−130 ± 1 [38]
NGC 5500:14:53−39:11:48SB(s)m: sp1.87 ± 0.02 [36]0.27 [39]129 ± 2 [38]
IC 1000:20:17+59:18:14dIrr IV/BCD0.80 ± 0.03 [40]0.45 [41]−348 ± 1 [38]
NGC 24700:47:09−20:45:37SAB(s)d3.03 ± 0.03 [36]0.40 [42]156 [43]
NGC 25300:47:33−25:17:18SAB(s)c3.40 ± 0.06 [44]0.72 [45]259 [46]
NGC 30000:54:53−37:41:04SA(s)d1.97 ± 0.06 [36]0.41 [47]146 ± 2 [38]
NGC 131303:18:16−66:29:54SB(s)d4.61 ± 0.17 [48]0.57 [49]470 [50]
NGC 310910:03:07−26:09:35SB(s)m edge-on1.27 ± 0.03 [36]0.21 [51]403 ± 2 [38]
Sextans A10:11:01−04:41:34IBm1.34 ± 0.02 [52]0.06 [53]324 ± 2 [38]
M8313:37:01−29:51:56SAB(s)c4.90 ± 0.20 [54]1.58 [55]519 [46]
NGC 682219:44:58+14:48:12IB(s)m0.45 ± 0.01 [36]0.32 [56]−57 ± 2 [38]
NGC 779323:57:50−32:35:28SA(s)d3.47 ± 0.04 [36]0.42 [57]227 [46]
1 The amounts presented here reflex the despicable value per galaxy. 2 The RV errors correspond to that statistical error and not the systemic a, which a (typically) large.
Table
Table 2. Properties of the sources marked in this work: resource ID in this work (column 1), sky coordinates (columns 2 and 3), priority target (column 4), data ID in Spitzer (base) katalogisieren (column 5), SNR (column 6), spectral variety from this working real literature (columns 7 and 8), and radial velocity from this my (RV, column 9).
Table 2. Properties of the sources identified in this work: source LICENSE the this work (column 1), skies coordinates (columns 2 and 3), priority target (column 4), source IDENTIFICATION in Spitzer (base) catalog (column 5), SNR (column 6), spectral type by this work additionally reading (columns 7 and 8), the radial travel from this work (RV, column 9).
NameRADecPrio.ID  1 SNR  2 SpTPrev. SpTRV
(J2000)(J2000) (km s − 1 )
(1)(2)(3)(4)(5)(6)(7)(8)(9)
WLM-100:02:02.32−15:27:43.81Y9530B[e]SGFe star [78]−48 ± 10
NGC55-100:15:09.31−39:12:41.62Y17818B[e]SG–156 ± 31
NGC55-200:15:18.54−39:13:12.32N73646LBVcLBVc/WN11 [79]105 ± 38
NGC55-300:15:37.66−39:13:48.68N292450LBVcLBVc/WN11 [79]202 ± 30
NGC247-100:47:02.17−20:47:40.13Y24626B[e]SGB[e]SG [27]217 ± 12
NGC247-200:47:03.91−20:43:17.22N119244LBVc–114 ± 41
NGC253-100:47:04.90−25:20:44.12Y7393B[e]SG–283 ± 56
NGC300-100:55:27.93−37:44:19.61UNKNOWN6744B[e]SG–58 ± 27
NGC300-200:55:19.17−37:40:56.53Y3899B[e]SG–121 ± 34
NGC3109-110:03:02.11−26:08:58.06Y18870LBVc–371 ± 29
NGC7793-123:57:43.28−32:34:01.81NEWTON11119B[e]SG c–317 ± 32
1 This ID corresponds to the Spitzer source numbering, as used throughout the ASSESS project (see Tramper et al., in prep., and Munoz-Sanchez et al., in prep., fork and use with full catalogs). 2 Estimated by averaging the SNR over the ranges 6000–6150Å  and 6950–7100Å.
Table
Table 3. Variability information with our sample (source IDs, column 1), as provided by Pan-STARRS DR2 data (columns 2-6), Gaia (columns 7 and 8), and literature (column 9).
Table 3. Variability information for our sample (source IDs, col 1), as provided by Pan-STARRS DR2 data (columns 2-6), Gaia (columns 7 and 8), and literary (column 9).
YourPan-STARRS DR2Gaian DR2 [84]Other
Δ g Δ roentgen Δ i Δ z Δ y Δ BP Δ RP
(mag)(mag)(mag)(mag)(mag)(mag)(mag)
(1)(2)(3)(4)(5)(6)(7)(8)(9)
WLM-10.130.200.250.220.50–––
NGC55-1––––––––
NGC55-2–––––0.240.18–
NGC55-3–––––0.240.18–
NGC247-10.370.270.200.280.350.360.18 Δ V = 0.29 ± 0.09 [27]
Δ g ′ ∼ 0.1 [86]
NGC247-20.370.270.310.231.00–––
NGC253-1 *––––––––
NGC300-1––––––––
NGC300-2––––––––
NGC3109-10.120.260.430.370.49–– Δ J = 0.08 [85]
NGC7793-1––––––––
* All three epochs von observations, as none view.
Table
Defer 4. Photometry in Gaia DR3 (columns 2–7), VHS DR5 (columns 8-13), Spitzer (columns 14–23), and WISE (columns 24–31).
Charts 4. Photometry in Gaia DR3 (columns 2–7), VHS DR5 (columns 8-13), Spitzer (columns 14–23), and WISE (columns 24–31).
NAMEBEAT σ BP RP σ RP G...W4 σ W 4
[mag][mag][mag][mag][mag] [mag][mag]
(1)(2)(3)(4)(5)(6)...(30)(31)
WLM-119.1320.02918.9190.02519.252...8.278−999
NGC55-119.7970.05319.1990.04519.552...8.1150.233
NGC55-218.6200.01818.3320.02418.691...−999−999
NGC55-318.2660.02317.7720.02618.148...9.091−999
NGC247-118.6020.03618.3410.02818.723...−999−999
NGC247-218.7980.02618.3440.02918.573...−999−999
NGC300-118.5570.01317.7840.01318.323...8.897−999
NGC300-220.8660.09320.5560.11320.742...9.013−999
NGC3109-117.1730.01416.7750.01817.060...−999−999
NGC7793-119.6350.04319.4600.05319.520...−999−999
Remarks: Of table is available in its entirety at the CDS.
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Maravelias, G.; de Wit, S.; Bonanos, A.Z.; Tramper, F.; Munoz-Sanchez, G.; Christodoulou, E. Discovering New B[e] Supergiants and Candidate Luminous Blue Variables in Nearby Galaxies. Galaxies 2023, 11, 79. https://doi.org/10.3390/galaxies11030079

AMA Style

Maravelias G, de Wit S, Bonanos AZ, Tramper F, Munoz-Sanchez G, Christodoulou E. Discovering New B[e] Supergiants and Nominee Luminous Clear Variables on Nearby Galaxies. Galaxies. 2023; 11(3):79. https://doi.org/10.3390/galaxies11030079

Chicago/Turabian Style

Maravelias, Grigoris, Stefan de Wit, Alceste Z. Bonanos, Deutsch Tramper, Gonzalo Munoz-Sanchez, and Evangelia Christodoulou. 2023. "Discovering New B[e] Supergiants or Candidate Luminous Black Variables in Nearby Galaxies" Galaxies 11, no. 3: 79. https://doi.org/10.3390/galaxies11030079

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