The IACOB project XIV. New clues on the location of the TAMS in the massive star domain

Abstract

Massive stars play a very important role in many astrophysical fields. Yet, some fundamental aspects of their evolution remain poorly constrained. In this regard, there is an open debate on the width of the main-sequence (MS) phase. We aim to create an updated Hertzsprung-Russell (HR) diagram that includes a volume-limited and statistically significant sample of massive stars. Our goal is to use this sample to investigate the extension of the MS, including information about projected rotational velocities ($v\sin i$) and the spectroscopic binary status. We combine spectroscopic parameters derived with FASTWIND stellar atmosphere code and Gaia distances to obtain stellar parameters for 876 Galactic luminous O- and B-type stars gathered within the IACOB project. We use the $\mathtt{iacob}-\mathtt{broad}$ tool to derive $v\sin i$ estimates and multi-epoch spectra to identify single/double-line spectroscopic binaries (SB1/SB2). We present an HR diagram for 670 stars located within 2500pc balancing completeness and number. We evaluate the extension of the MS in terms of the drop in the relative number of stars as a function of effective temperature ($T_{\mathrm{eff}}$). We find a consistent boundary at $\approx$22.5kK within the full range of luminosities that we use to delineate the terminal-age main sequence (TAMS). We obtain a smooth decrease of the highest $v\sin i$ with $T_{\mathrm{eff}}$ along the MS, likely limited by the critical velocity. We consider this effect combined with a lower expected fraction of stars beyond the MS as the best explanation for the lack of fast-rotating objects in the post-MS region. Our results favor low to mild initial rotation for the full sample and a binary past for the tail of fast-rotating stars. The prominence of SB1/SB2 systems in the MS, and the 25% decrease in the relative fraction of SB1 systems when crossing the TAMS can further delineate its location.

16 pages, 9 figures, accepted for publication in A&A

References in corpus (34)

• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• Binary interaction dominates the evolution of massive stars
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Pre-Supernova Evolution of Massive Single and Binary Stars
• The VLT-FLAMES survey of massive stars: atmospheric parameters and rotational velocity distributions for B-type stars in the Magellanic Clouds
• Gaia Data Release 3: Catalogue Validation
• The evolution of rotating very massive stars with LMC composition
• Low-frequency gravity waves in blue supergiants revealed by high-precision space photometry
• The spectroscopic Hertzsprung-Russell diagram
• The spectroscopic Hertzsprung-Russell diagram of Galactic massive stars
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars II. A grid of O-type stars in the Galaxy and the Magellanic Clouds
• Constraining mixing in massive stars in the Small Magellanic Cloud
• Variability of OB stars from TESS southern Sectors 1-13 and high-resolution IACOB and OWN spectroscopy
• The mass discrepancy in intermediate- and high-mass eclipsing binaries: the need for higher convective core masses
• The VLT-FLAMES Tarantula Survey XIX. B-type Supergiants - Atmospheric parameters and nitrogen abundances to investigate the role of binarity and the width of the main sequence
• The metallicity dependence of envelope inflation in massive stars
• The dependence of convective core overshooting on stellar mass: reality check, and additional evidence
• The Alma catalog of OB stars. II. A cross-match with Gaia DR2 and an updated map of the solar neighbourhood
• The effects of surface fossil magnetic fields on massive star evolution: II. Implementation of magnetic braking in MESA and implications for the evolution of surface rotation in OB stars
• The IACOB project. VII. The rotational properties of Galactic massive O-type stars revisited
• The IACOB project. VI. On the elusive detection of massive O-type stars close to the ZAMS
• Convective core sizes in rotating massive stars: I. Constraints from solar metallicity OB field stars
• Very Massive Stars in High-Redshift Galaxies
• Stellar parameters and H$\alpha$ line profile variability of Be stars in the BeSOS survey
• Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds. V. Complete comoving frame transfer, and updated modeling of X-ray emission
• Upper Mass-Loss Limits and Clumping in the Intermediate and Outer Wind Regions of OB stars
• The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities
• Time-dependent modeling of extended thin decretion disks of critically rotating stars
• The IACOB project X. Large-scale quantitative spectroscopic analysis of Galactic luminous blue stars
• The IACOB project VIII. Searching for empirical signatures of binarity in fast-rotating O-type stars
• The IACOB project IX. Building a modern empirical database of Galactic O9-B9 supergiants: sample selection, description, and completeness
• High-resolution spectroscopic study of massive blue and red supergiants in Per OB1
• The IACOB project XI. No increase of mass-loss rates over the bistability region

Cited by in corpus (6)

• Binarity at LOw Metallicity (BLOeM): Multiplicity of early B-type supergiants in the Small Magellanic Cloud
• Binarity at LOw Metallicity (BLOeM): Projected rotational velocities
• An observational study of rotation and binarity of Galactic O-type runaway stars
• Chemical fingerprints of binary mass transfer in massive stars
• The symphony of pulsations and binarity among massive stars using HERMES spectroscopy and TESS photometry
• The AMBRE Project: Line-broadening and stellar rotation of ESO/FEROS archived spectra