Properties of an Eclipsing Double White Dwarf Binary NLTT 11748

Kaplan, D. L.; Marsh, T. R.; Walker, A.; Bildsten, Lars; Bours, Madelon C. P.; Breedt, E.; Copperwheat, C. M.; Dhillon, V. S.; Howell, Steve B.; Littlefair, S. P.; Shporer, Avi; Steinfadt, Justin D. R.

doi:10.1088/0004-637x/780/2/167

Cited by 28 publications

(28 citation statements)

References 60 publications

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“…However, Kaplan et al (2014) show that there is significant (up to 25 per cent) disagreement between the spectroscopically determined mass of the eclipsing ELM WD NLTT 11748 and the mass derived from detailed light curve modelling.…”

Section: Introductionmentioning

confidence: 90%

PSR J1738+0333: the first millisecond pulsar + pulsating white dwarf binary

Kilic

Hermes

Gianninas

et al. 2014

Monthly Notices of the Royal Astronomical Society: Letters

104

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We report the discovery of the first millisecond pulsar with a pulsating white dwarf companion. Following the recent discoveries of pulsations in extremely lowmass (ELM, 0.3 M ⊙ ) white dwarfs (WDs), we targeted ELM WD companions to two millisecond pulsars with high-speed Gemini photometry. We find significant optical variability in PSR J1738+0333 with periods between roughly 1790 − 3060 s, consistent in timescale with theoretical and empirical observations of pulsations in ≈0.17 M ⊙ He-core ELM WDs. We additionally put stringent limits on a lack of variability in PSR J1909−3744, showing this ELM WD is not variable to < 0.1 per cent amplitude. Thanks to the accurate distance and radius estimates from radio timing measurements, PSR J1738+0333 becomes a benchmark for low-mass, pulsating WDs. Future, more extensive time-series photometry of this system offers an unprecedented opportunity to constrain the physical parameters (including the cooling age) and interior structure of this ELM WD, and in turn, the mass and spin-down age of its pulsar companion.

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Section: Introductionmentioning

confidence: 90%

PSR J1738+0333: the first millisecond pulsar + pulsating white dwarf binary

Kilic

Hermes

Gianninas

et al. 2014

Monthly Notices of the Royal Astronomical Society: Letters

104

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“…NLTT 11748 is discussed above; it is an eclipsing system where the spectroscopically inferred radius from the 1D models was significantly smaller than the eclipse modeling suggested (Gianninas et al 2014a;Kaplan et al 2014). Studying the radius constraints on the ELM WD sample, Gianninas et al (2014a) find that the agreement between the spectroscopically inferred radii and the model-independent values is quite good for T 10,000 eff > K. However, there are four relatively cool objects, LP 400-22, NLTT 11748, J0745, and J0751, where the radius is underestimated or the mass/ g log is overestimated.…”

Section: The Mass-radius Relationmentioning

confidence: 99%

“…The 1D spectroscopic analysis of Gianninas et al (2014a) Kaplan et al (2014) use high-quality photometry of NLTT 11748 to constrain the same parameters from the observed eclipses. Depending on the thickness of the surface hydrogen layer of the secondary (more massive) WD, they derive M 1 = 0.136-0.162 M e and R 1 = 0.0423-0.0433 R e .…”

Section: Tablementioning

confidence: 99%

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3d Model Atmospheres for Extremely Low-Mass White Dwarfs

Tremblay

Gianninas

Kilic

et al. 2015

ApJ

114

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We present an extended grid of mean three-dimensional (3D) spectra for low-mass, pure-hydrogen atmosphere DA white dwarfs (WDs). We use CO5BOLD radiation-hydrodynamics 3D simulations covering T eff = 6000-11,500 K and log g = 5-6.5 (g in cm s −2 ) to derive analytical functions to convert spectroscopically determined 1D temperatures and surface gravities to 3D atmospheric parameters. Along with the previously published 3D models, the 1D to 3D corrections are now available for essentially all known convective DA WDs (i.e., log g = 5-9). For low-mass WDs, the correction in temperature is relatively small (a few percent at the most), but the surface gravities measured from the 3D models are lower by as much as 0.35 dex. We revisit the spectroscopic analysis of the extremely low-mass (ELM) WDs, and demonstrate that the 3D models largely resolve the discrepancies seen in the radius and mass measurements for relatively cool ELM WDs in eclipsing double WD and WD + millisecond pulsar binary systems. We also use the 3D corrections to revise the boundaries of the ZZ Ceti instability strip, including the recently found ELM pulsators.

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“…Kaplan et al 2014, and references therein). These WDs often have a massive CO WD companion and evolved via stable RLO in cataclysmic variable (CV) systems.…”

Section: Observational Properties Of Msps With He Wds In Tight Orbitsmentioning

confidence: 99%

The formation of low-mass helium white dwarfs orbiting pulsars

Istrate

Tauris

Langer

2014

A&A

117

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Context. Millisecond pulsars (MSPs) are generally believed to be old neutron stars (NSs) that have been spun up to high rotation rates via accretion of matter from a companion star in a low-mass X-ray binary (LMXB). This scenario has been strongly supported by various pieces of observational evidence. However, many details of this recycling scenario remain to be understood. Aims. Here we investigate binary evolution in close LMXBs to study the formation of radio MSPs with low-mass helium white dwarf companions (He WDs) in tight binaries with orbital periods P orb 2−9 h. In particular, we examine i) if the observed systems can be reproduced by theoretical modelling using standard prescriptions of orbital angular momentum losses (i.e. with respect to the nature and the strength of magnetic braking), ii) if our computations of the Roche-lobe detachments can match the observed orbital periods, and iii) if the correlation between WD mass and orbital period (M WD , P orb ) is valid for systems with P orb < 2 days. Methods. Numerical calculations with a detailed stellar evolution code were used to trace the mass-transfer phase in ∼400 close LMXB systems with different initial values of donor star mass, NS mass, orbital period, and the so-called γ-index of magnetic braking. Subsequently, we followed the orbital and the interior evolution of the detached low-mass (proto) He WDs, including stages with residual shell hydrogen burning. Results. We find that severe fine-tuning is necessary to reproduce the observed MSPs in tight binaries with He WD companions of mass <0.20 M , which suggests that something needs to be modified or is missing in the standard input physics of LMXB modelling. Results from previous independent studies support this conclusion. We demonstrate that the theoretically calculated (M WD , P orb )-relation is in general also valid for systems with P orb < 2 days, although with a large scatter in He WD masses between 0.15−0.20 M . The results of the thermal evolution of the (proto) He WDs are reported in a follow-up paper (Paper II).

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Properties of an Eclipsing Double White Dwarf Binary NLTT 11748

Cited by 28 publications

References 60 publications

PSR J1738+0333: the first millisecond pulsar + pulsating white dwarf binary

PSR J1738+0333: the first millisecond pulsar + pulsating white dwarf binary

3d Model Atmospheres for Extremely Low-Mass White Dwarfs

The formation of low-mass helium white dwarfs orbiting pulsars

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