The UV-brightest Stars of M33 and Its Nucleus: Discovery, Photometry, and Optical Spectroscopy

Massey, Philip; Bianchi, Luciana; Hutchings, J. B.; Stecher, T. P.

doi:10.1086/177811

Cited by 84 publications

(159 citation statements)

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“…It is the brightest supergiant in M 33 with UV-excess (Massey et al 1996). Based on spectral criteria, luminosity, and the absence of a large-amplitude variability, B 416 may be classified as B[e]-supergiant star (Zickgraf et al 1986;Lamers et al 1998b The presence of anisotropical mass loss is a common and distinguishing property of B[e]-supergiants (Lamers et al 1998b).…”

Section: Discussionmentioning

confidence: 99%

“…Systematic surveys of LBV-like candidates in massive galaxies (Calzetti et al 1995;Massey et al 1996;Corral 1996;) provide a basis for isolating these objects for subsequent follow-up and quantative spectroscopy (Massey et al 1996;Sholukhova et al 1997Sholukhova et al , 1999 to reveal the basic properties of these objects. In M 33 there are 4 confirmed LBV stars and about a dozen LBV candidates, but only one known Ofpe/WN star, and about 5 new candidates for this latter class of objects (Massey et al 1996). Not a single SS433-type star has been found in M 33, and also no B[e]-supergiant has been confirmed to date.…”

Section: Introductionmentioning

confidence: 99%

“…The first star was designated as blue star N 416 in the photographic survey by Humphreys & Sandage (1980). It was also identified as an LBV candidate in follow-up spectroscopy of the UV-brightest stars of M 33 (Massey et al 1996). In a program searching for SS 433-like stars in M 33, Shemmer & Leibowitz (1998) detected periodic microvariations in the photometry of B 416.…”

Section: Introductionmentioning

confidence: 99%

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Crowded field 3D spectroscopy of LBV candidates in M 33

Fabrika¹,

Sholukhova²,

Becker³

et al. 2005

A&A

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Abstract. We present integral field spectroscopy of the LBV candidate stars B 416 and v 532 in the local group galaxy M 33. B 416 is surrounded by an elongated ring-like nebula, which has a projected radius of 20 × 30 pc. From the datacube we create ionization and radial velocity maps of the nebula. The excitation of the gas decreases towards the outer part of the ring, while the inner part of the nebula is filled with a more excited gas. In the EW direction the ring is seen to expand with a maximum projected velocity amplitude of about 40 km s −1 . The eastern part approaches the observer. We estimate the nebula dynamical lifetime ∼8 × 10 5 years. It could be a residual MS bubble, which indicates a main-sequence or pre-LBV status of the star. We classify B 416 as an "iron star" or B[e]-supergiant. In v 532 an elongated nebula has been marginally detected. The total projected size of the nebula along the main axis is 30 pc, and the total radial velocity gradient is 44 ± 11 km s −1 . v 532 exhibits both strong photometric and spectral variability. At the time of our observations it was in an intermediate brightness state with a rich nitrogen spectrum. We classify v 532 as an LBV, showing LBV ↔ Ofpe/WN transitions. We stress the importance of integral field spectroscopy as the optimal technique for studying nebulae and the evolution of LBV-like stars in nearby galaxies.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Crowded field 3D spectroscopy of LBV candidates in M 33

Fabrika¹,

Sholukhova²,

Becker³

et al. 2005

A&A

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“…We cross-correlated our source list with the following catalogs: The XMM-Newton survey of M33 (Pietsch et al 2004), the ROSAT source catalog (Haberl & Pietsch 2001), the catalog of SNRs by Gordon et al (1999), H ii regions from Hodge et al (1999), giant molecular clouds from Engargiola et al (2003), globular clusters from Mochejska et al (1998), star clusters from Chandar et al (1999Chandar et al ( , 2001, blue and red supergiants from Ivanov et al (1993), red supergiants from Massey (1998), WolfRayet stars from Massey & Johnson (1998), UV-bright stars from Massey et al (1996), hot stars from Massey et al (1995), OB associations from Regan & Wilson (1993), planetary nebulae from Magrini et al (2001), H emitters from Calzetti et al (1995), and the DIRECT star catalog from Macri et al (2001).…”

Section: Counterpartsmentioning

confidence: 99%

The X‐Ray Binary Population in M33. I. Source List and Luminosity Function

Grimm¹,

McDowell²,

Zezas³

et al. 2005

ASTROPHYS J SUPPL S

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In this paper we present the source list for three Chandra observations of the Local Group galaxy M33. The observations are centered on the nucleus and on the star-forming region NGC 604. We detect a total of 261 sources in an area of $0.2 deg 2 down to a flux limit of 3 ; 10 À16 ergs s À1 cm À2 , which corresponds to a luminosity of $2 ; 10 34 ergs s À1 at a distance of 840 kpc. From the source list we construct the luminosity functions of sources observed in M33. If we take into account background contamination, the luminosity functions are consistent with those of other star-forming galaxies. In addition, the combination of X-ray color analysis and the existence of ''blue'' optical counterparts strongly indicates that the X-ray point-source population in M33 consists of young objects. Above 3 ; 10 35 ergs s À1 there are few X-ray sources in the locus of the X-ray hardness ratio diagram that is generally populated by low-mass X-ray binaries.

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“…A spectrum taken in December 1993 (Massey et al , 1996(Massey et al , 2007 Another spectrum taken on 7 October 2013 by Humphreys et al (2014) showed much weaker hydrogen lines in emission, Ca ii and Mg ii in absorption, and Fe ii in emission with P-Cygni profiles. The spectrum is classified as late A-type.…”

Section: Spectra Of Var Cmentioning

confidence: 97%

Var C: Long-term photometric and spectral variability of a luminous blue variable in M 33

Burggraf

Weis

Bomans

et al. 2015

A&A

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Aims. So far the highly unstable phase of luminous blue variables (LBVs) has not been understood well. It is still uncertain why and which massive stars enter this phase. Investigating the variabilities by looking for a possible regular or even (semi-)periodic behaviour could give a hint at the underlying mechanism for these variations and might answer the question of where these variabilities originate. Finding out more about the LBV phase also means understanding massive stars better in general, which have (e.g. by enriching the ISM with heavy elements, providing ionising radiation and kinetic energy) a strong and significant influence on the ISM, hence also on their host galaxy. Methods. Photometric and spectroscopic data were taken for the LBV Var C in M 33 to investigate its recent status. In addition, scanned historic plates, archival data, and data from the literature were gathered to trace Var C's behaviour in the past. Its long-term variability and periodicity was investigated. Results. Our investigation of the variability indicates possible (semi-)periodic behaviour with a period of 42.3 years for Var C. That Var C's light curve covers a time span of more than 100 years means that more than two full periods of the cycle are visible. The critical historic maximum around 1905 is less strong but discernible even with the currently rare historic data. The semi-periodic and secular structure of the light curve is similar to the one of LMC R71. Both light curves hint at a new aspect in the evolution of LBVs.

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The UV-brightest Stars of M33 and Its Nucleus: Discovery, Photometry, and Optical Spectroscopy

Cited by 84 publications

References 0 publications

Crowded field 3D spectroscopy of LBV candidates in M 33

Crowded field 3D spectroscopy of LBV candidates in M 33

The X‐Ray Binary Population in M33. I. Source List and Luminosity Function

Var C: Long-term photometric and spectral variability of a luminous blue variable in M 33

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