Absolute magnitudes of OB and Be stars based on Hipparcos parallaxes

Wegner, W.

doi:10.1046/j.1365-8711.2000.03884.x

Cited by 52 publications

(44 citation statements)

References 15 publications

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“…The scope of this paper is somewhat similar to that of Wegner (2000), who devises a new absolute magnitude calibration of OB stars based on the Hipparcos results. The author eliminates negative parallaxes by applying a transformation proposed by Smith & Eichhorn (1996).…”

Section: Discussionmentioning

confidence: 78%

On the Hipparcos parallaxes of O stars

Schroeder¹,

Kaper²,

Lamers³

2004

A&A

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Abstract. We compare the absolute visual magnitude of the majority of bright O stars in the sky as predicted from their spectral type with the absolute magnitude calculated from their apparent magnitude and the Hipparcos parallax. We find that many stars appear to be much fainter than expected, up to five magnitudes. We find no evidence for a correlation between magnitude differences and the stellar rotational velocity as suggested for OB stars by Lamers et al. (1997, A&A, 325, L25), whose small sample of stars is partly included in ours. Instead, by means of a simulation we show how these differences arise naturally from the large distances at which O stars are located, and the level of precision of the parallax measurements achieved by Hipparcos. Straightforwardly deriving a distance from the Hipparcos parallax yields reliable results for one or two O stars only. We discuss several types of bias reported in the literature in connection with parallax samples (Lutz-Kelker, Malmquist) and investigate how they affect the O star sample. In addition, we test three absolute magnitude calibrations from the literature (Schmidt-Kaler et al. 1982, Landolt-Börnstein; Howarth & Prinja 1989, ApJS, 69, 527; Vacca et al. 1996, ApJ, 460, 914) and find that they are consistent with the Hipparcos measurements. Although O stars conform nicely to the simulation, we notice that some B stars in the sample of Lamers et al. have a magnitude difference larger than expected.

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Section: Discussionmentioning

confidence: 78%

On the Hipparcos parallaxes of O stars

Schroeder¹,

Kaper²,

Lamers³

2004

A&A

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“…A new calibration based on Hipparcos distances has been derived by Wegner (2000), who finds on average rather lower absolute magnitudes at a given spectral type than previously assumed (typically by ∼1 mag). By using this calibration, we could solve the problem of our three underluminous objects, but we would create a larger one, since the magnitudes that we derive (typically M V ≈ −4 for B0V objects) would then mean that all the other counterparts are bright giants.…”

Section: Discussionmentioning

confidence: 98%

The population of massive X-ray binaries

Negueruela¹,

Coe²

2002

A&A

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Abstract. We present high resolution blue spectroscopy of an almost complete sample of optical counterparts to massive X-ray binaries in the Large Magellanic Cloud (LMC) and derive their spectral classification. We find an spectral type B0II for the optical counterpart to RX J0532.5−6551, confirming it as the first wind-fed massive X-ray binary in the LMC. We also confirm the Be nature of the proposed counterpart to RX J0535.0−6700. The proposed optical counterpart to RX J0531.5−6518 is a B2V star with signs of emission in the Balmer lines. In total, we give accurate spectral types for 14 counterparts. We find that the overall observed population of massive X-ray binaries in the LMC has a distribution not very different from the observed Galactic population and we discuss different selection effects affecting our knowledge of this population. The spectral distribution of the Be/X-ray binary population is also rather similar to the Galactic one. This distribution implies that Be/X-ray binaries must have preferentially formed from moderately massive binaries undergoing semi-conservative evolution. The observation of several Be/X-ray binaries with large eccentricities implies then the existence of supernova kicks.

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“…From these maps we looked for stars with absolute V-band magnitudes in the typical range of the Galactic Be stars, i.e. −6 < M V < 0 (Wegner 2000;Garmany & Humphreys 1985). Assuming a distance modulus for the Galactic Bulge of 14.5 mag (Mc Namara et al 2000), we obtained apparent magnitudes in the range of 8.5 + A V < V < 14.5 + A V , where A V is mean extinction value for each field of the Galactic Bulge obtained from Sumi (2004).…”

Section: The Datamentioning

confidence: 99%

A catalogue of Be stars in the direction of the Galactic Bulge

Sabogal¹,

Mennickent²,

Pietrzyński

et al. 2007

A&A

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Context. Detailed studies of Be stars in environments with different metallicities like the Magellanic Clouds or the Galactic Bulge are necessary to understand the formation and evolution mechanisms of the circumstellar disks. However, a detailed study of Be stars in the direction of the bulge of our own galaxy has not been performed until now. Aims. The aim of this work is to report the first systematic search for Be star candidates in the direction of the Galactic Bulge. We present the full catalogue, give a brief description of the stellar variability seen, and show some light curve examples. Methods. We searched for stars matching specific criteria of magnitude, color and variability in the I band. Our search was conducted on the 48 OGLE II fields of the Galactic Bulge.Results. This search has resulted in 29053 Be star candidates, 198 of them showing periodic light variations. Nearly 1500 stars in this final sample are almost certainly Be stars, providing an ideal sample for spectroscopic multi-object follow-up studies.

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Absolute magnitudes of OB and Be stars based on Hipparcos parallaxes

Cited by 52 publications

References 15 publications

On the Hipparcos parallaxes of O stars

On the Hipparcos parallaxes of O stars

The population of massive X-ray binaries

A catalogue of Be stars in the direction of the Galactic Bulge

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