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Detection of a white dwarf companion to the white dwarf SDSSJ125733.63+542850.5
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Marsh, T. R., Gaensicke, B. T., Steeghs, D., Southworth, J., Koester, Detlev, Harris, V. and Merry, L. (2011) Detection of a white dwarf companion to the white dwarf SDSSJ125733.63+542850.5. The Astrophysical Journal, Vol.736 (No.2). p. 95. doi:10.1088/0004-637X/736/2/95
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WRAP_STeeghs_White_Dwarf_1002.4677v2.pdf - Accepted Version Download (936Kb) | Preview |
Official URL: http://dx.doi.org/10.1088/0004-637X/736/2/95
Abstract
SDSSJ125733.63+542850.5 (hereafter SDSSJ1257+5428) is a compact white dwarf binary from the Sloan Digital Sky Survey that exhibits high-amplitude radial velocity variations on a period of 4.56 hr. While an initial analysis suggested the presence of a neutron star or black hole binary companion, a follow-up study concluded that the spectrum was better understood as a combination of two white dwarfs. Here we present optical spectroscopy and ultraviolet fluxes which directly reveal the presence of the second white dwarf in the system. SDSSJ1257+5428's spectrum is a composite, dominated by the narrow-lined spectrum from a cool, low-gravity white dwarf (T eff 6300 K, log g = 5-6.6) with broad wings from a hotter, high-mass white dwarf companion (11, 000-14, 000 K; ~1 M ). The high-mass white dwarf has unusual line profiles which lack the narrow central core to Hα that is usually seen in white dwarfs. This is consistent with rapid rotation with vsin i = 500-1750 km s–1, although other broadening mechanisms such as magnetic fields, pulsations, or a helium-rich atmosphere could also be contributory factors. The cool component is a puzzle since no evolutionary model matches its combination of low gravity and temperature. Within the constraints set by our data, SDSSJ1257+5428 could have a total mass greater than the Chandrasekhar limit and thus be a potential Type Ia supernova progenitor. However, SDSSJ1257+5428's unusually low-mass ratio q 0.2 suggests that it is more likely that it will evolve into an accreting double white dwarf (AM CVn star).
| Item Type: | Journal Article | ||||
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| Subjects: | Q Science > QB Astronomy | ||||
| Divisions: | Faculty of Science > Physics | ||||
| Library of Congress Subject Headings (LCSH): | Double stars, Supernovae, White dwarf stars | ||||
| Journal or Publication Title: | The Astrophysical Journal | ||||
| Publisher: | Institute of Physics Publishing, Inc. | ||||
| ISSN: | 0004-637X | ||||
| Official Date: | August 2011 | ||||
| Dates: |
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| Volume: | Vol.736 | ||||
| Number: | No.2 | ||||
| Page Range: | p. 95 | ||||
| DOI: | 10.1088/0004-637X/736/2/95 | ||||
| Status: | Peer Reviewed | ||||
| Publication Status: | Published | ||||
| Access rights to Published version: | Restricted or Subscription Access | ||||
| Funder: | Science and Technology Facilities Council (Great Britain) (STFC) | ||||
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