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 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 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 1998PASP..110...79F) and the 600 line/mm grating.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 102 61 ELM WD Physical Parameters
table2.dat 111 61 ELM WD Binary Parameters
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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
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Bytes Format Units Label Explanations
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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
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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 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.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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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
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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.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 24-Apr-2017