J/ApJ/794/35 Binary white dwarfs atmospheric parameters (Gianninas+, 2014)
Precise atmospheric parameters for the shortest-period binary white dwarfs: gravitational waves, metals, and pulsations. Gianninas A., Dufour P., Kilic M., Brown W.R., Bergeron P., Hermes J.J. <Astrophys. J., 794, 35 (2014)> =2014ApJ...794...35G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, double and multiple ; Stars, white dwarf ; Stars, masses ; Effective temperatures ; Stars, diameters ; Photometry, SDSS ; Stars, distances Keywords: binaries: close - stars: abundances - stars: fundamental parameters - techniques: spectroscopic - white dwarfs Abstract: We present a detailed spectroscopic analysis of 61 low-mass white dwarfs and provide precise atmospheric parameters, masses, and updated binary system parameters based on our new model atmosphere grids and the most recent evolutionary model calculations. For the first time, we measure systematic abundances of He, Ca, and Mg for metal-rich, extremely low mass white dwarfs and examine the distribution of these abundances as a function of effective temperature and mass. Based on our preliminary results, we discuss the possibility that shell flashes may be responsible for the presence of the observed He and metals. We compare stellar radii derived from our spectroscopic analysis to model-independent measurements and find good agreement except for white dwarfs with Teff≲10000 K. We also calculate the expected gravitational wave strain for each system and discuss their significance to the eLISA space-borne gravitational wave observatory. Finally, we provide an update on the instability strip of extremely low mass white dwarf pulsators. Description: The sample that we analyze includes a total of 61 ELM WD binaries from the ELM Survey (Brown et al. 2013, J/ApJ/769/66). The bulk of this sample is comprised of the 58 ELM WDs listed in Table 3 of Brown et al. (2013, J/ApJ/769/66), but also includes three additional ELM WDs that have been published in separate papers since then. The spectra of these 61 ELM WDs were obtained using five distinct setups on two different telescopes. A total of 57 targets were observed with the 6.5m MMT telescope with the Blue Channel spectrograph (Schmidt et al. 1989PASP..101..713S). The four remaining targets were observed using the Fred Lawrence Whipple Observatory's (FLWO) 1.5m Tilinghast telescope equipped with the FAST spectrograph (Fabricant et al. 1998PASP..110...79F) and the 600 line/mm grating. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 102 61 ELM WD Physical Parameters table2.dat 111 61 ELM WD Binary Parameters
See also: J/AJ/129/2428 : M dwarf-white dwarf binary systems (Silvestri+, 2005) J/AJ/134/26 : Binaries with white dwarf in 2MASS (Hoard+, 2007) J/A+A/486/843 : White dwarf-red dwarf binaries in the SDSS (Augusteijn+, 2008) J/ApJ/769/66 : The ELM survey. V. White dwarf binaries (Brown+, 2013) J/ApJ/818/155 : The ELM survey. VII. 15 new ELM white dwarf cand. (Brown+, 2016) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 10 A10 --- SDSS SDSS identifier (JHHMM+DDMM), EQ JHHMM+DDMM in Simbad 14 A1 --- f_SDSS [bc] Flag on SDSS (1) 16- 20 I5 K Teff Effective temperature 22- 24 I3 K e_Teff Uncertainty in Teff 26- 29 F4.2 [cm/s2] log(g) Log surface gravity 31- 34 F4.2 [cm/s2] e_log(g) Uncertainty in log(g) 36- 40 F5.3 Msun Mass Mass (2) 42- 47 F6.4 Rsun Rad Radius 49- 54 F6.4 Rsun e_Rad Uncertainty in Rad 56- 61 F6.3 mag gmag SDSS g band magnitude; extinction corrected 63- 67 F5.3 mag e_gmag Uncertainty in gmag 69- 73 F5.2 mag gMag Absolute SDSS g band magnitude 75- 78 F4.2 mag e_gMag Uncertainty in gMag 80- 84 F5.3 kpc Dist Distance 86- 90 F5.3 kpc e_Dist Uncertainty in Dist 92- 96 F5.3 Gyr tauc Cooling timescale 98-102 F5.3 Gyr e_tauc Uncertainty in tauc
Note (1): Flag as follows: b = NLTT 11748; since this WD is outside the SDSS footprint, we adopt the V magnitude from Kawka & Vennes (2009A&A...506L..25K) instead of gmag. c = LP 400-22. Note (2): We adopt an uncertainty of 0.020 M☉ for all estimates of the primary mass.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 10 A10 --- SDSS SDSS identifier (JHHMM+DDMM) 12- 18 F7.5 d P ? Period 20- 26 F7.5 d e_P ? Uncertainty in P 29- 30 A2 --- l_K [≤ ] Limit flag on K 33- 37 F5.1 km/s K Velocity semi-amplitude 39- 41 F3.1 km/s e_K ? Uncertainty in K 43- 47 F5.3 Msun MF ? Mass Function 49- 53 F5.3 Msun e_MF ? Uncertainty in MF 56- 57 A2 --- l_M2 [≥ ] Limit flag on M2 61- 64 F4.2 Msun M2 ? Secondary mass 66- 69 F4.2 Msun e_M2 ? Uncertainty in M2 71- 74 F4.2 Msun M2-60 ? Secondary mass assuming inclination=60 76- 79 F4.2 Msun e_M2-60 ? Uncertainty in M2-60 81 A1 --- f_M2-60 [a] Flag on M2-60 (1) 84- 85 A2 --- l_taum [≤ ] Limit flag on tau 89- 94 F6.3 Gyr taum ? Merging timescale 96- 99 F4.2 Rsun Sep ? Separation 101-104 F4.2 Rsun e_Sep ? Uncertainty in Sep 106-111 F6.2 [-] log(h) ? Log gravitational wave strain
Note (1): Flag as follows: a = Eclipsing systems where we adopt M2 and i as determined from the eclipse modeling (see Section 4.2) instead of assuming i=60 degrees.
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 24-Apr-2017
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