A double white dwarf with a paradoxical origin?

Abstract

We present Hubble Space Telescope UV spectra of the 4.6 h period double white dwarf SDSS J125733.63+542850.5. Combined with Sloan Digital Sky Survey optical data, these reveal that the massive white dwarf (secondary) has an effective temperature T2 = 13030 +/- 70 +/- 150 K and a surface gravity log g2 = 8.73 +/- 0.05 +/- 0.05 (statistical and systematic uncertainties respectively), leading to a mass of M2 = 1.06 Msun. The temperature of the extremely low-mass white dwarf (primary) is substantially lower at T1 = 6400 +/- 37 +/- 50 K, while its surface gravity is poorly constrained by the data. The relative flux contribution of the two white dwarfs across the spectrum provides a radius ratio of R1/R2 = 4.2, which, together with evolutionary models, allows us to calculate the cooling ages. The secondary massive white dwarf has a cooling age of about 1 Gyr, while that of the primary low-mass white dwarf is likely to be much longer, possibly larger than 5 Gyrs, depending on its mass and the strength of chemical diffusion. These results unexpectedly suggest that the low-mass white dwarf formed long before the massive white dwarf, a puzzling discovery which poses a paradox for binary evolution.

accepted for publication in MNRAS

References in corpus (53)

• emcee: The MCMC Hammer
• The Sloan Digital Sky Survey: Technical Summary
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• A Massive Pulsar in a Compact Relativistic Binary
• Comprehensive analytic formulae for stellar evolution as a function of mass and metallicity
• The PPMXL catalog of positions and proper motions on the ICRS. Combining USNO-B1.0 and 2MASS
• The gravitational wave signal from the Galactic disk population of binaries containing two compact objects
• An Improved Spectroscopic Analysis of DA White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• Faint Thermonuclear Supernovae from AM Canum Venaticorum Binaries
• A Spectroscopic Survey & Analysis of Bright, Hydrogen-Rich White Dwarfs
• ULTRACAM: an ultra-fast, triple-beam CCD camera for high-speed astrophysics
• A millisecond pulsar in a stellar triple system
• Found: The missing blue opacity in atmosphere models of cool hydrogen white dwarfs
• New evolutionary sequences for extremely low mass white dwarfs: Homogeneous mass and age determinations, and asteroseismic prospects
• The initial-final mass relationship of white dwarfs revisited: effect on the luminosity function and mass distribution
• The Long-Term Evolution of Double White Dwarf Mergers
• Spectroscopic analysis of DA white dwarfs with 3D model atmospheres
• The ELM Survey. I. A Complete Sample of Extremely Low Mass White Dwarfs
• Prelude to a double degenerate merger: the onset of mass transfer and its impact on gravitational waves and surface detonations
• The masses of the millisecond pulsar J1012+5307 and its white-dwarf companion
• The ELM Survey. II. Twelve Binary White Dwarf Merger Systems
• The Merger Rate of Binary White Dwarfs in the Galactic Disk
• KOI 1224, a Fourth Bloated Hot White Dwarf Companion Found With Kepler
• Parallax and Distance Estimates for Fourteen Cataclysmic Variable Stars
• Rapid Orbital Decay in the 12.75-minute WD+WD Binary J0651+2844
• The formation of low-mass helium white dwarfs orbiting pulsars: Evolution of low-mass X-ray binaries below the bifurcation period
• EL CVn-type binaries - Discovery of 17 helium white dwarf precursors in bright eclipsing binary star systems
• The age and colors of massive white dwarf stars
• The masses of PSR J1911-5958A and its white dwarf companion
• Formation of the Galactic Millisecond Pulsar Triple System PSR J0337+1715 - a Neutron Star with Two Orbiting White Dwarfs
• The ELM Survey. IV. 24 White Dwarf Merger Systems
• The ELM Survey. V. Merging Massive White Dwarf Binaries
• PopCORN: Hunting down the differences between binary population synthesis codes
• Ensemble Characteristics of the ZZ Ceti stars
• The timescale of low-mass proto-helium white dwarf evolution
• The ELM Survey. III. A Successful Targeted Survey for Extremely Low Mass White Dwarfs
• A Metal-Rich Low-Gravity Companion to a Massive Millisecond Pulsar
• Precise Atmospheric Parameters for the Shortest Period Binary White Dwarfs: Gravitational Waves, Metals, and Pulsations
• The Thermal State of the Accreting White Dwarf in AM Canum Venaticorum Binaries
• Found: The Progenitors of AM CVn and Supernovae .Ia
• PSR J1738+0333: The First Millisecond Pulsar + Pulsating White Dwarf Binary
• First Results from the Swarms Survey. SDSS 1257+5428: A Nearby, Massive White Dwarf Binary with a Likely Neutron Star or Black Hole Companion
• CSS100603:112253-111037: A helium-rich dwarf nova with a 65 minute orbital period
• Discovery of an ultramassive pulsating white dwarf
• The (Double) White Dwarf Binary SDSS 1257+5428
• A New Gravitational Wave Verification Source
• Timing of a Young Mildly Recycled Pulsar with a Massive White Dwarf Companion
• Parallax and Distance Estimates for Twelve Cataclysmic Variable Stars
• Detection of a white dwarf companion to the white dwarf SDSSJ125733.63+542850.5
• Properties of the Eclipsing Double-White Dwarf Binary NLTT 11748
• SDSS J074511.56+194926.5: Discovery of a Metal-Rich and Tidally Distorted Extremely Low Mass White Dwarf
• Heavy metals in a light white dwarf: Abundances of the metal-rich, extremely low-mass GALEX J1717+6757

Cited by in corpus (17)

• Models of low-mass helium white dwarfs including gravitational settling, thermal and chemical diffusion, and rotational mixing
• On the evolution of ultra-massive white dwarfs
• The separation distribution and merger rate of double white dwarfs: improved constraints
• A Catalogue of Potential Post Common Envelope Binaries
• Towards a volumetric census of close white dwarf binaries I.Reference samples
• GALEX Absolute Calibration and Extinction Coefficients Based on White Dwarfs
• The evolution of ultra-massive carbon oxygen white dwarfs
• Structure and evolution of ultra-massive white dwarfs in general relativity
• Influence of a mass transfer stability criterion on double white dwarf populations
• Carbon-oxygen ultra-massive white dwarfs in general relativity
• The Discovery of Two LISA Sources within 0.5 kpc
• Formation and Evolution of Accreting Compact Objects
• Massive Double White Dwarfs and the AM CVn Birthrate
• Today a Duo, But Once a Trio? The Double White Dwarf HS 2220$+$2146 May Be A Post-Blue Straggler Binary
• Resolution of a paradox: SDSS J1257+5428 can be explained as a descendant of a cataclysmic variable with an evolved donor
• A strange dwarf scenario for the formation of the peculiar double white dwarf binary SDSS J125733.63+542850.5
• Magnetic dynamos in white dwarfs -III: explaining the occurrence of strong magnetic fields in close double white dwarfs