AM Canum Venaticorum progenitors with helium star donors and the resultant explosions

Journal Article · Wed Jul 01 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/807/1/74· OSTI ID:22882964

Brooks, Jared; Bildsten, Lars ^[1]; Marchant, Pablo ^[2]; Paxton, Bill ^[3]

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1. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
2. Argelander-Institut für Astronomie, Bonn, D-53121 (Germany)
3. Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)

We explore the outcome of mass transfer via Roche lobe overflow of M{sub He}≲0.51M{sub ⊙} pure helium burning stars in close binaries with WDs. The evolution is driven by the loss of angular momentum through gravitational wave radiation (GWR), and both stars are modeled using Modules for Experiments in Stellar Astrophysics (MESA). The donors have masses of M{sub He}=0.35,0.4,and0.51M{sub ⊙} and accrete onto WDs of mass M{sub WD} from 0.6M{sub ⊙} to 1.26M{sub ⊙}. The initial orbital periods (P{sub orb}) span 20–80 minutes. For all cases, the accretion rate onto the WD is below the stable helium burning range, leading to accumulation of helium followed by unstable ignition. The mass of the convective core in the donors is small enough so that the WD accretes enough helium-rich matter to undergo a thermonuclear runaway in the helium shell before any carbon–oxygen enriched matter is transferred. The mass of the accumulated helium shell depends on M{sub WD} and the accretion rate. We show that for M{sub He}≳0.4M{sub ⊙} and M{sub WD}≳0.8M{sub ⊙}, the first flash is likely vigorous enough to trigger a detonation in the helium layer. These thermonuclear runaways may be observed as either faint and fast Ia SNe or, if the carbon in the core is also detonated, Type Ia SNe. Those that survive the first flash and eject mass will have a temporary increase in orbital separation, but GWR drives the donor back into contact, resuming mass transfer and triggering several subsequent weaker flashes.

• OSTI ID: 22882964
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 807; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANGULAR MOMENTUM
ASTROPHYSICS
CARBON
GRAVITATIONAL WAVES
HELIUM
HELIUM BURNING
MASS TRANSFER
NOVAE
OXYGEN
ROCHE EQUIPOTENTIALS
SUPERNOVAE
WHITE DWARF STARS