Luminous and Variable Stars in M31 and M33. IV. Luminous Blue Variables, Candidate LBVs, and the B[e] Supergiants; How to Tell Them Apart

Abstract

In this series of papers we have presented the results of a spectroscopic survey of luminous and variable stars in the nearby spirals M31 and M33. In this paper, we present spectroscopy of 132 additional luminous stars, variables, and emission line objects. Most of the stars have emission line spectra, including LBVs and candidate LBVs, Fe II emission line stars and the B[e] supergiants, and the warm hypergiants. Many of these objects are spectroscopically similar and are often confused with each other. With this large spectroscopic data set including various types of emission line stars, we examine their similarities and differences and propose the following criteria that can be used to help distinguish these stars in future work: 1. The B[e] supergiants have emission lines of [O I] and [Fe II] in their spectra. Most of the spectroscopically confirmed sgB[e] stars also have warm circumstellar dust in their SEDs. 2. Confirmed LBVs do not have the [O I] emission lines in their spectra. Some LBVs have [Fe II] emission lines, but not all. Their SEDS shows free-free emission in the near-infrared but no evidence for warm dust. Their most important and defining characteristic is the S Dor-type variability. 3. The warm hypergiants spectroscopically resemble both the LBVs in their eruption or dense wind state and the B[e] supergiants. However, they are very dusty. Some have [Fe II] and [O I] emission in their spectra like the sgB[e] stars, but can be distinguished by their absorption line spectra characteristic of A and F-type supergiants. In contrast, the B[e] supergiant spectra have strong continua and few if any apparent absorption lines.

arXiv comment42 pages, 6 figures, 7 tables. Submitted to ApJ for publication, November 2016

References in corpus (30)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The death of massive stars - I. Observational constraints on the progenitors of type II-P supernovae
• Observational constraints on the progenitors of core-collapse supernovae : the case for missing high mass stars
• A Survey of Local Group Galaxies Currently Forming Stars. I. UBVRI Photometry of Stars in M31 and M33
• Hectospec, the MMT's 300 Optical Fiber-Fed Spectrograph
• A New Class of Luminous Transients and A First Census of Their Massive Stellar Progenitors
• A Survey of Local Group Galaxies Currently Forming Stars: III. A Search for Luminous Blue Variables and Other H-alpha Emission-Lined Stars
• DIRECT Distances to Nearby Galaxies Using Detached Eclipsing Binaries and Cepheids. I. Variables in the Field M31B
• The Wolf-Rayet Content of M33
• On the Social Traits of Luminous Blue Variables
• Deep CFHT Photometric Survey of the Entire M33 Galaxy I: Catalogue of 36000 Variable Point Sources
• Luminous and Variable Stars in M31 and M33. I. The Warm Hypergiants and Post-Red Supergiant Evolution
• The Supernova Progenitor Mass Distributions of M31 and M33: Further Evidence for an Upper Mass Limit
• Probing the ejecta of evolved massive stars in transition: A VLT/SINFONI K-band survey
• The M33 Variable Star Population Revealed by Spitzer
• A Spectroscopic Survey of Massive Stars in M31 and M33
• Luminous and Variable Stars in M31 and M33. II. Luminous Blue Variables, Candidate LBVs, Fe II Emission Line Stars, and Other Supergiants
• On the nature of candidate luminous blue variables in M33
• A new observational tracer for high-density disc-like structures around B[e] supergiants
• Luminous and Variable Stars in M31 and M33. III. The Yellow and Red Supergiants and Post-Red Supergiant Evolution
• Spectroscopic survey of emission-line stars. I. B[e] stars
• Discovery of the first B[e] supergiants in M 31
• Wolf-Rayet Stars in M33 II: Optical Spectroscopy of emission-line stars in Giant Hii Regions
• New Luminous Blue Variables in the Andromeda galaxy
• A point source survey of M31 with the Spitzer Space Telescope
• The Wind of Variable C in M33
• Search for LBV Candidates in the M33 Galaxy
• Properties of M31. IV: Candidate Luminous Blue Variables from PAndromeda
• Var C: Long-term photometric and spectral variability of an LBV in M33
• A New Luminous Blue Variable in M31

Cited by in corpus (40)

• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) I. Ultraviolet to Infrared Photometry of 22 Million Stars in M33
• Anomaly detection in the Zwicky Transient Facility DR3
• Shedding Light on the Isolation of Luminous Blue Variables
• Luminous and Variable Stars in M31 and M33 V. The Upper HR Diagram
• How common is LBV S Dor variability at low metallicity?
• Uncovering Red and Dusty Ultraluminous X-ray Sources with Spitzer
• The 2018 Census of Luminous Blue Variables
• Optical/near-infrared observations of the Fried Egg Nebula: Multiple shell ejections on a 100 yr timescale from a massive yellow hypergiant
• A machine-learning photometric classifier for massive stars in nearby galaxies I. The method
• A spectroscopic study of blue supergiant stars in Local Group spiral galaxies: Andromeda and Triangulum
• The Curious Case of PHL 293B: A Long-Lived Transient in a Metal-Poor Blue Compact Dwarf Galaxy
• On the evolutionary state of massive stars in transition phases in M33
• Luminous and Variable Stars in NGC 2403 and M81
• Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy
• New Luminous Blue Variable Candidates in NGC 4736
• The study of unclassified B[e] stars and candidates in the Galaxy and Magellanic Clouds
• Monitoring luminous yellow massive stars in M33: new yellow hypergiant candidates
• A new outburst of the yellow hypergiant star Rho Cas
• First Detection of Mid-Infrared Variability from an Ultraluminous X-Ray Source Holmberg II X-1
• New luminous blue variable candidates in the NGC 247 galaxy
• Multi-Epoch BVRI Photometry of Luminous Stars in M31 and M33
• Luminous Blue Variable candidates in M31
• A massive nebula around the Luminous Blue Variable star RMC143 revealed by ALMA
• Modeling spectra of MN112
• To the problem of spectral mimicry of supergiants
• The History Goes On: Century Long Study of Romano's Star
• Discovering new B[e] supergiants and candidate Luminous Blue Variables in nearby galaxies
• A Long-term photometric variability and spectroscopic study of luminous blue variable AF And in M31
• How long can LBVs sleep? A long-term photometric vaiability and spectral study of the Galactic candidate luminous blue variable MN112
• Search for LBVs in the Local Volume galaxies: study of four stars in NGC 4449
• The Complex Upper HR Diagram
• An Optical and Infrared Time-Domain Study of the Supergiant Fast X-ray Transient Candidate IC 10 X-2
• Accretion in the Binary System GG Carinae and Implications for B[e] Supergiants
• On the spatial distribution of luminous blue variables in the M33 galaxy
• Photometric and spectroscopic analysis of LBV candidate J004341.84+411112.0 in M31
• Massive Stars in Molecular Clouds Rich in High-energy Sources: The Bridge of G332.809-0.132 and CS 78 in NGC 6334
• A machine-learning photometric classifier for massive stars in nearby galaxies II. The catalog
• New Blue and Red Variable Stars in NGC 247
• The incidence of LBV variability in the LMC