A Spectroscopic Survey of Massive Stars in M31 and M33*

Massey, Philip; Neugent, Kathryn F.; Smart, Brianna

doi:10.3847/0004-6256/152/3/62

Cited by 55 publications

(124 citation statements)

References 75 publications

(151 reference statements)

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“…However, several stars in each galaxy have negative derived A v 's. All except one are described as isolated (I) by Massey et al (2016). We therefore assume that the anomalous A v values are due to photometric error or unresolved blends and replace them with our mean values, 0.62 ± 0.02 mag for M31 and 0.33 ± 0.01 mag for M33, determined from the other stars.…”

Section: The Observational Data For the Supergiant Populationsmentioning

confidence: 99%

“…too high in M v and M Bol . Eight were classed as extremely crowded (X) by Massey et al (2016). We checked all 13 stars and confirm that these 8 were blended, unresolved images, or embedded in nebulosity.…”

Section: The Observational Data For the Supergiant Populationsmentioning

confidence: 99%

“…Two of the supergiants in M31 with very high extinction values, > 3 mag, are classed as isolated (I) by Massey et al (2016) which means that their spectra and photometry are not contaminated by unresolved nearby stars. It does not mean that they are physically isolated from other luminous stars.…”

Section: A Two Exceptionally Luminous O-type Supergiants In M31mentioning

confidence: 99%

“…We use the large data set published by Massey et al (2016), together with our own spectral classifications from Papers II, III and IV, to create a catalog of luminous O,B and A type stars representative of the hot star populations in M31 and M33. We are careful to avoid duplication, and only stars with spectral types are used.…”

Section: The Observational Data For the Supergiant Populationsmentioning

confidence: 99%

“…In this final paper we present the upper HR Diagrams for M31 and M33 based on this work and that of Massey (2016). We determine the luminosities of the emission line stars from Papers II and IV to place them on the HR Diagram for comparison with their respective massive star populations and a discussion of their possible evolutionary state.…”

Section: Introduction -The Complex Upper Hr Diagrammentioning

confidence: 99%

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Luminous and Variable Stars in M31 and M33. V. The Upper HR Diagram

Humphreys

Davidson

Hahn

et al. 2017

ApJ

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We present HR Diagrams for the massive star populations in M31 and M33 including several different types of emission-line stars: the confirmed Luminous Blue Variables (LBVs), candidate LBVs, B[e] supergiants and the warm hypergiants. We estimate their apparent temperatures and luminosities for comparison with their respective massive star populations and to evaluate the possible relationships of these different classes of evolved, massive stars, and their evolutionary state. Several of the LBV candidates lie near the LBV/S Dor instability strip which supports their classification. Most of the B[e] supergiants, however, are less luminous than the LBVs. Many are very dusty with the infrared flux contributing one-third or more to their total flux. They are also relatively isolated from other luminous OB stars. Overall, their spatial distribution suggests a more evolved state. Some may be post-RSGs like the warm hypergiants, and there may be more than one path to becoming a B[e] star. There are sufficient differences in the spectra, luminosities, spatial distribution, and the presence or lack of dust between the LBVs and B[e] supergiants to conclude that one group does not evolve into the other.

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Section: The Observational Data For the Supergiant Populationsmentioning

confidence: 99%

Section: The Observational Data For the Supergiant Populationsmentioning

confidence: 99%

Section: A Two Exceptionally Luminous O-type Supergiants In M31mentioning

confidence: 99%

Section: The Observational Data For the Supergiant Populationsmentioning

confidence: 99%

Section: Introduction -The Complex Upper Hr Diagrammentioning

confidence: 99%

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Luminous and Variable Stars in M31 and M33. V. The Upper HR Diagram

Humphreys

Davidson

Hahn

et al. 2017

ApJ

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Monitoring luminous yellow massive stars in M 33: new yellow hypergiant candidates

Kourniotis

Bonanos

Yuan

et al. 2017

A&A

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Context. The evolution of massive stars surviving the red supergiant (RSG) stage remains unexplored due to the rarity of such objects. The yellow hypergiants (YHGs) appear to be the warm counterparts of post-RSG classes located near the Humphreys-Davidson upper luminosity limit, which are characterized by atmospheric instability and high mass-loss rates. Aims. We aim to increase the number of YHGs in M33 and thus to contribute to a better understanding of the pre-supernova evolution of massive stars. Methods. Optical spectroscopy of five dust-enshrouded yellow supergiants (YSGs) selected from mid-IR criteria was obtained with the goal of detecting evidence of extensive atmospheres. We also analyzed BV I c photometry for 21 of the most luminous YSGs in M33 spanning approximately nine years to identify changes in the spectral type that are expected based on the few well-studied YHGs. To explore the properties of circumstellar dust, we performed spectral energy distribution fitting of multi-band photometry of the 21 YSGs. We additionally conducted K−band spectroscopy of the YHG candidate B324 in search of processed ejected material. Results. We find three luminous YSGs in our sample, stars 2, 6 and 13, with log L/L ⊙ 5.35 to be YHG candidates, as they are surrounded by hot dust and are enshrouded within extended, cold dusty envelopes. Our spectroscopy of star 2 shows emission of more than one Hα component, as well as emission of Ca ii and [N ii], implying an extended atmospheric structure. In addition, the long-term monitoring of the star reveals a dimming in the visual light curve of amplitude larger than 0.5 mag that caused an apparent drop in the temperature that exceeded 500 K. We suggest the observed variability to be analogous to that of the Galactic YHG ρ Cas. We further support the post-RSG classification of N125093 and B324 instead of being LBVs in outburst. Five less luminous YSGs are suggested as post-RSG candidates showing evidence of hot or/and cool dust emission. Conclusions. We demonstrate that mid-IR photometry, combined with optical spectroscopy and time-series photometry, provide a robust method for identifying candidate YHGs. Future discovery of YHGs in Local Group galaxies is critical for the study of the late evolution of intermediate-mass massive stars.

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MUSE crowded field 3D spectroscopy in NGC 300

Roth

Sandín

Kamann

et al. 2018

A&A

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Aims. As a new approach to the study of resolved stellar populations in nearby galaxies, our goal is to demonstrate with a pilot study in NGC 300 that integral field spectroscopy with high spatial resolution and excellent seeing conditions reaches an unprecedented depth in severely crowded fields. Methods. MUSE observations with seven pointings in NGC 300 have resulted in datacubes that are analyzed in four ways: (1) PSF-fitting 3D spectroscopy with PampelMUSE, as already successfully pioneered in globular clusters, yields deblended spectra of individually distinguishable stars, thus providing a complete inventory of blue/red supergiants, and AGB stars of type M and C. The technique is also applicable to emission line point sources and provides samples of planetary nebulae that are complete down to m 5007 =28.(2) pseudo-monochromatic images, created at the wavelengths of the most important emission lines and corrected for continuum light by using the P3D visualization tool, provide maps of H ii regions, supernova remnants, and the diffuse interstellar medium at a high level of sensitivity, where also faint point sources stand out and allow for the discovery of planetary nebulae, WR stars etc. (3) The use of the P3D line-fitting tool yields emission line fluxes, surface brightness, and kinematic information for gaseous objects, corrected for absorption line profiles of the underlying stellar population in the case of Hα. (4) Visual inspection of the datacubes by browsing through the row-stacked-spectra image in P3D is demonstrated to be efficient for data mining and the discovery of background galaxies and unusual objects. Results. We present a catalogue of luminous stars, rare stars such as WR and other emission line stars, carbon stars, symbiotic star candidates, planetary nebulae, H ii regions, supernova remnants, giant shells, peculiar diffuse and filamentary emission line objects, and background galaxies, along with their spectra. Conclusions. The technique of crowded-field 3D spectroscopy, using the PampelMUSE code, is capable of deblending individual bright stars, the unresolved background of faint stars, gaseous nebulae, and the diffuse component of the interstellar medium, resulting in unprecedented legacy value for observations of nearby galaxies with MUSE.

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A Spectroscopic Survey of Massive Stars in M31 and M33*

Cited by 55 publications

References 75 publications

Luminous and Variable Stars in M31 and M33. V. The Upper HR Diagram

Luminous and Variable Stars in M31 and M33. V. The Upper HR Diagram

Monitoring luminous yellow massive stars in M 33: new yellow hypergiant candidates

MUSE crowded field 3D spectroscopy in NGC 300

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