The origin of subdwarf B stars – II

  title={The origin of subdwarf B stars – II},
  author={Zhan-wen Han and Philipp Podsiadlowski and Pierre F. L. Maxted and Thomas R. Marsh},
  journal={Monthly Notices of the Royal Astronomical Society},
We have carried out a detailed binary population synthesis (BPS) study of the formation of subdwarf B (sdB) stars and related objects (sdO, sdOB stars) using the latest version of the BPS code developed by Han and co-workers. We systematically investigate the importance of the five main evolutionary channels in which the sdB stars form after one or two common-envelope (CE) phases, one or two phases of stable Roche lobe overflow (RLOF) or as the result of the merger of two helium white dwarfs… 
Formation of hot subdwarf B stars with neutron star components
Context. Binary population synthesis predicts the existence of subdwarf B stars (sdBs) with neutron star (NS) or black hole (BH) companions. Several works have been dedicated to finding such systems,
Subdwarf B stars from the common envelope ejection channel
From the canonical binary scenario, the majority of sdBs are produced from low-mass stars with degenerate cores where helium is ignited in a way of flashes. Due to numerical difficulties, the models
Hot subdwarf B stars with neutron star components
Context: Subdwarf B stars (sdBs) play a crucial role in stellar evolution, asteroseismology, and far-UV radiation of early-type galaxies, and have been intensively studied with observation and
Radial-velocity measurements of subdwarf B stars
Subdwarf B (sdB) stars are hot, subluminous stars which are thought to be core-helium burning with thin hydrogen envelopes. The mechanism by which these stars lose their envelopes has been
Population Synthesis of Hot Subdwarfs: A Parameter Study
Binaries that contain a hot subdwarf (sdB) star and a main-sequence companion may have interacted in the past. This binary population has historically helped determine our understanding of binary
The orbital periods of subdwarf B binaries produced by the first stable Roche Lobe overflow channel
Long-orbital-period subdwarf B (sdB) stars with main-sequence companions are believed to be the product of stable Roche Lobe overflow (RLOF), a scenario challenged by recent observations. Here, we
The empirical mass distribution of hot B subdwarfs: implications for stellar evolution theory
Subdwarf B (sdB) stars are hot, compact, and evolved objects that form the very hot end of the horizontal branch, the so-called Extreme Horizontal Branch (EHB). Understanding the formation of sdB
On the formation of single and binary helium-rich sdO stars
We propose a formation channel for the previously unexplained helium-rich subdwarf O (He-rich sdO) stars in which post-subdwarf B (sdB) stars (i.e. hybrid COHe white dwarfs) reignite helium burning
Composite hot subdwarf binaries - I. The spectroscopically confirmed sdB sample
Hot subdwarf-B (sdB) stars in long-period binaries are found to be on eccentric orbits, even though current binary-evolution theory predicts that these objects are circularized before the onset of
Hot subdwarfs from the ESO Supernova Ia Progenitor Survey - I. Atmospheric parameters and cool companions of sdB stars
We present the analysis of a high-resolution, high-quality sample of optical spectra for 76 subdwarf B (sdB) stars from the ESO Supernova Ia Progenitor Survey (SPY, Napiwotzki et al. 2001). Effective


The origin of subdwarf B stars – I. The formation channels
Subdwarf B (sdB) stars (and related sdO/sdOB stars) are believed to be helium-core-burning objects with very thin hydrogen-rich envelopes. In recent years it has become increasingly clear from
Orbital periods of 22 subdwarf B stars
Subdwarf B (sdB) stars are thought to be core helium burning stars with low mass hydrogen envelopes. In recent years it has become clear that many sdB stars lose their hydrogen through interaction
Physical parameters of sdB stars from spectral energy distributions
The atmospheric parameters of 34 hot subdwarf B stars have been obtained using a combination of 61 short and long-wave IUE spectra, together with new and existing optical and infrared photometric
Close Binary White Dwarf Systems: Numerous New Detections and Their Interpretation
We describe radial velocity observations of a large sample of apparently single white dwarfs (WDs), obtained in a long-term effort to discover close double-degenerate (DD) pairs, which might comprise
The binary fraction of extreme horizontal branch stars
We have used precise radial velocity measurements of subdwarf-B stars from the Palomar–Green catalogue to look for binary extreme horizontal branch (EHB) stars. We have determined the effective
Resolving subdwarf B stars in binaries by HST imaging
The origin of subluminous B stars is still an unsolved problem in stellar evolution. Single star as well as close binary evolution scenarios have been invoked but until now have met with little
KPD 0422+5421: a new short-period subdwarf B/white dwarf binary
The sdB star KPD 0422+5421 was discovered to be a single-lined spectroscopic binary with a period of P = 0.0901795±(3×10 −7 ) days (2 hours, 10 minutes). The U and B light curves display an
KPD 1930+2752: a candidate Type Ia supernova progenitor
We present spectra of the pulsating sdB star KPD 1930+2752 which confirm that this star is a binary. The radial velocities measured from the Hα and He i 6678-A spectral lines vary sinusoidally with
Binaries discovered by the SPY project I. HE 1047{0436: A subdwarf B + white dwarf system ?;??
In the course of our search for double degenerate binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO S NI aProgenitor surveY { SPY) we discovered
The end Stage of Stellar Evolution: White Dwarfs, Hot Subdwarfs and Nuclei of Planetary Nebulae
The region of the H—R diagram to the left and below the main sequence (see Figure 1) is occupied by stars whose nuclear-burning phases are either ending or essentially ended. These objects for the