A STELLAR ROTATION CENSUS OF B STARS: FROM ZAMS TO TAMS

By Wenjin Huang, D. Gies, M. McSwain. 2010

144 citations recorded by the source corpus.

Two recent observing campaigns provide us with moderate dispersion spectra of more than 230 cluster and 370 field B stars. Combining them and the spectra of the B stars from our previous investigations (∼430 cluster and ∼100 field B stars) yields a large, homogeneous sample for studying the rotational properties of B stars. We derive the projected rotational velocity Vsin i, effective temperature, gravity, mass, and critical rotation speed Vcrit for each star. We find that the average Vsin i is significantly lower among field stars because they are systematically more evolved and spun down than their cluster counterparts. The rotational distribution functions of Veq/Vcrit for the least evolved B stars show that lower mass B stars are born with a larger proportion of rapid rotators than higher mass B stars. However, the upper limit of Veq/Vcrit that may separate normal B stars from emission-line Be stars (where rotation promotes mass loss into a circumstellar disk) is smaller among the higher mass B stars. We compare the evolutionary trends of rotation (measured according to the polar gravity of the star) with recent models that treat internal mixing. The spin-down rates observed in the high-mass subset (∼9 M☉) agree with predictions, but the rates are larger for the low-mass group (∼3 M☉). The faster spin-down in the low-mass B stars matches well with the predictions based on conservation of angular momentum in individual spherical shells. Our results suggest that the fastest rotators (that probably correspond to the emission-line Be stars) are probably formed by evolutionary spin-up (for the more massive stars) and by mass transfer in binaries (for the full range of B star masses).

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5139937ea4526a861a2b3be23fbc7e10177889b7

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

The IACOB project - I. Rotational velocities in northern Galactic O- and early B-type stars revisited. The impact of other sources of line-broadening (2013, background): “For a more complete overview of the distribution of projected rotational velocities in B-type stars in the Milky Way we refer to, e.g., Abt et al. (200), Strom et al. (2005), Huang & Gies (2006, 2008), Wolff et al. (2007), Huang et al. (2010), Bragança et al. (2012).”
EXTRACTING RADIAL VELOCITIES OF A- AND B-TYPE STARS FROM ECHELLE SPECTROGRAPH CALIBRATION SPECTRA (2015, background): “…the multiplicity of A- and F-type dwarfs with rapid rotation rates, Chini et al. (2012), who examined the binary fraction among B- and O-type stars, and Huang et al. (2010), who examined radial velocities as a larger-scale effort to measure the projected rotational velocities of massive stars.”
THE ROTATION RATES OF MASSIVE STARS: THE ROLE OF BINARY INTERACTION THROUGH TIDES, MASS TRANSFER, AND MERGERS (2012, background): “…compare our results with observed distributions of rotational velocities of massive main-sequence stars (e.g., Mokiem et al. 2006; Daflon et al. 2007; Wolff et al. 2008; Hunter et al. 2008b; Penny & Gies 2009; Huang et al. 2010; Dufton et al. 2013; O. Ramı́rez-Agudelo et al. 2013, in preparation).”
Classical Be stars (2013, methodology): “Huang et al. (2010), using observational data from open clusters, approach the problem from the B star side, and identify the highest W observed in the distribution of non-Be stars.”
Delay-time distribution of core-collapse supernovae with late events resulting from binary interaction (2017, background): “Although this does not account for the full distribution (e.g., Huang et al. 2010; Dufton et al. 2013; Ramírez-Agudelo et al. 2013, 2015), this is sufficient for investigating the role of binarity as the impact of the adopted birth spin is negligible compared to the angular momentum the star later…”
Rotational velocities of A-type stars - IV. Evolution of rotational velocities (2012, methodology): “For some stars in the sample of Huang et al. (2010) uvby–β photometry is not available, so that we used the Teff estimates derived by these authors.”
A CHARA ARRAY SURVEY OF CIRCUMSTELLAR DISKS AROUND NEARBY Be-TYPE STARS (2013, result): “These results support earlier Be star angular velocity ratio estimates of 0.88 (Frémat et al. 2005), 0.7 – 1.0 (Cranmer 2005), 0.8 – 1.0 (Huang et al. 2010), and 0.95 ± 0.02 (Meilland et al. 2012).”
MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, background): “The observed rotational distribution function is quite broad (Huang et al. 2010) and also the observed stars were most likely born with a range of initial metallicities, which would increase scatter in the observed nitrogen abundances.”