A detection of the evolutionary time scale of the DA white dwarf G117 - B15A with the Whole Earth Telescope

Kepler, S. O.; Winget, D. E.; Nather, R. E.; Bradley, P. A.; Grauer, A. D.; Fontaine, G.; Bergeron, P.; Vauclair, G.; Claver, C. F.; Marar, T. M. K.; Seetha, S.; Ashoka, B. N.; Mazeh, T.; Leibowitz, E. M.; Dolez, N.; Chevreton, M.; Barstow, M. A.; Clemens, J. C.; Kleinman, S. J.; Sansom, A. E.; Tweedy, R. W.; Kanaan, A.; Hine, Butler; Provençal, J. L.; Wesemaël, F.; Wood, M. A.; Brassard, P.; Solheim, J. E.; Emanuelsen, P. I.

doi:10.1086/186138

Cited by 73 publications

(40 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The O-C technique is much more sensitive than the direct method of plotting period as a function of time; this is because it has the advantage of adding up the discrepancy O-C over the entire timebase of observations consisting of numerous cycles. Neglecting higher order terms, Kepler et al (1991) showed the derivation of the following O-C equation using a Taylor series expansion of the phase of a slowly changing period:…”

Section: O-c Diagrammentioning

confidence: 99%

Constraining the Angular Momentum Evolution of V455 Andromedae

Mukadam

Pyrzas

Townsley

et al. 2016

ApJ

View full text Add to dashboard Cite

Time-series photometry on the cataclysmic variable V455Andromedae (hereafter V455And, HS 2331+3905) reveals a rotation period shorter than the orbital period, implying the presence of a magnetic field. We expect that this magnetic field channels the accreted matter from the disk toward the white dwarf poles, classifying it as an Intermediate Polar. The two polar spinning emission areas are visible in the lightcurves at the rotation period of 67.61970396 ± 0.00000072 s, and its harmonic. Using photometric observations of V455And obtained from 2007 October to 2015, we derive 3σ upper limits to the rate of change of the spin harmonic (SH) with time to be dP SH / dt −7.5 × 10 −15 s s −1 employing the O-C method, and −5.4 × 10 −15 s s −1 with a direct nonlinear least squares fit. There is no significant detection of a changing spin period for the duration of 2007 October-2015. The 3σ upper limit for the rate of change of spin period with time is dP spin /dt −10.8 × 10 −15 s s −1 or −0.34 μs yr −1 . V455And underwent a large-amplitude dwarf nova outburst in 2007 September. The pre-outburst data reflect a period 4.8 ± 2.2 μs longer than the best-fit post-outburst spin period. The angular momentum gained by the white dwarf from matter accreted during outburst and its slight subsequent shrinking should both cause the star to spin slightly faster after the outburst. We estimate that the change in spin period due to the outburst should be 5 μs, consistent with the empirical determination of 4.8 ± 2.2 μs (3σ upper limit of 11.4 μs).

show abstract

Section: O-c Diagrammentioning

confidence: 99%

Constraining the Angular Momentum Evolution of V455 Andromedae

Mukadam

Pyrzas

Townsley

et al. 2016

ApJ

View full text Add to dashboard Cite

show abstract

“…J0651 has a measuredṖ orb = 9.8 ± 2.8 × 10 −12 s s −1 which is consistent with GR predictions (Hermes et al 2012) within the error. The way this is typically measured is to compare the observed (O) mid-eclipse times with computed (C) values from a model with constant orbital period and fit the O − C values as a function of time (e.g., Kepler et al 1991). A possible resulting parabola gives evidence of a finite value ofṖ orb (Sterken 2005).…”

Section: Uncertainties From the Em Datamentioning

confidence: 99%

Measuring Tides and Binary Parameters From Gravitational Wave Data and Eclipsing Timings of Detached White Dwarf Binaries

Shah

Nelemans

2014

ApJ

View full text Add to dashboard Cite

The discovery of the most compact detached white dwarf (WD) binary SDSS J065133.33+284423.3 has been discussed in terms of probing the tidal effects in WDs. This system is also a verification source for the space-based gravitational wave (GW) detector, eLISA, or the evolved Laser Interferometer Space Antenna, which will observe short-period compact Galactic binaries with P orb 5 hr. We address the prospects of performing tidal studies using eLISA binaries by showing the fractional uncertainties in the orbital decay rate,ḟ , and the rate of that decay,f expected from both the GW and electromagnetic (EM) data for some of the high-f binaries. We find thatḟ and f can be measured using GW data only for the most massive WD binaries observed at high frequencies. From timing the eclipses for ∼10 yr, we find thatḟ can be known to ∼0.1% for J0651. We find that from GW data alone, measuring the effects of tides in binaries is (almost) impossible. We also investigate the improvement in the knowledge of the binary parameters by combining the GW amplitude and inclination with EM data with and withoutḟ . In our previous work, we found that EM data on distance constrained the 2σ uncertainty in chirp mass to 15%-25% whereas addingḟ reduces it to 0.11%. EM data onḟ also constrain the 2σ uncertainty in distance to 35%-19%. EM data on primary mass constrain the secondary mass m 2 to factors of two to ∼40% whereas addinġ f reduces this to 25%. Finally, using single-line spectroscopic data constrains 2σ uncertainties in both the m 2 , d to factors of two to ∼40%. Adding EM data onḟ reduces these 2σ uncertainties to 25% and 6%-19%, respectively. Thus we find that EM measurements ofḟ and radial velocity are valuable in constraining eLISA binary parameters.

show abstract

“…Interestingly, the rate of increase in the pulsation period of the ZZ Ceti variable G117-B15A (Kepler et al 1991), which appears too large in comparison with the expectations from CO white dwarf models, has motivated an accelerated cooling scenario (Isern, Hernanz, & Garcia-Berro 1992) in which an excess cooling by axions of an estimated mass m a ' (8 3)= cos 2 meV might be taking place. However, recent results by Vauclair (1994) suggest that the variability is not as large as previously reported, and also that no obvious periodicity is present.…”

Section: Axionsmentioning

confidence: 99%

The Helium-Core Mass at the Helium Flash in Low-Mass Red Giant Stars: Observations and Theory

Catelan¹,

Pacheco²,

Horvath³

1996

ApJ

View full text Add to dashboard Cite

The method developed by Ra elt (1990a,b,c) to estimate a possible increase in the standard values of the helium-core mass at the tip of the red giant branch, M c , from properties of the color-magnitude diagrams of Galactic globular clusters is employed. In the present study, we revise and update Ra elt's database, including also constraints from RR Lyrae pulsation, and nd that a small increase, by M c 0:01 0:015 M , cannot be ruled out with the present data and evolutionary models. Our new upper limits on M c are less restrictive than those previously obtained by Ra elt, as are the corresponding constraints on novel astroparticle phenomena which may a ect the evolution of low-mass red giants. Within the estimated uncertainties, however, the standard values of M c may also be acceptable. Ra elt's method does not rule out a low envelope helium abundance in globular cluster giants, though again the standard values are compatible with the available constraints. The in uence of a non-solar ratio for the -capture elements upon these results is also investigated. In addition, we review several aspects of the input physics employed in red giant stellar evolutionary calculations, with the purpose of evaluating possible sources of uncertainty in the value of the helium-core mass at the helium ash that is obtained from evolutionary computations, such as: heat conduction by electrons in the degenerate core; Coulomb e ects upon the Equation of State; triple-reaction rates and screening factors; neutrino emission rates, both standard and enhanced by a possible non-zero magnetic moment; stellar rotation; microscopic element di usion; and energy losses by axions and Weakly Interacting Massive Particles.

show abstract

A detection of the evolutionary time scale of the DA white dwarf G117 - B15A with the Whole Earth Telescope

Cited by 73 publications

References 0 publications

Constraining the Angular Momentum Evolution of V455 Andromedae

Constraining the Angular Momentum Evolution of V455 Andromedae

Measuring Tides and Binary Parameters From Gravitational Wave Data and Eclipsing Timings of Detached White Dwarf Binaries

The Helium-Core Mass at the Helium Flash in Low-Mass Red Giant Stars: Observations and Theory

Contact Info

Product

Resources

About