J/ApJ/848/11 Spectroscopic and photometric analysis of WDs (Bedard+, 2017)
Measurements of physical parameters of white dwarfs: a test of the mass-radius
relation.
Bedard A., Bergeron P., Fontaine G.
<Astrophys. J., 848, 11-11 (2017)>
=2017ApJ...848...11B 2017ApJ...848...11B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf; Spectral types; Effective temperatures;
Stars, diameters; Stars, masses; Stars, distances
Keywords: stars: fundamental parameters; techniques: photometric;
techniques: spectroscopic
Abstract:
We present a detailed spectroscopic and photometric analysis of 219 DA
and DB white dwarfs for which trigonometric parallax measurements are
available. Our aim is to compare the physical parameters derived from
the spectroscopic and photometric techniques, and then to test the
theoretical mass-radius relation for white dwarfs using these results.
The agreement between spectroscopic and photometric parameters is
found to be excellent, especially for effective temperatures, showing
that our model atmospheres and fitting procedures provide an accurate,
internally consistent analysis. The values of surface gravity and
solid angle obtained, respectively, from spectroscopy and photometry,
are combined with parallax measurements in various ways to study the
validity of the mass-radius relation from an empirical point of view.
After a thorough examination of our results, we find that 73% and 92%
of the white dwarfs are consistent within 1σ and 2σ
confidence levels, respectively, with the predictions of the
mass-radius relation, thus providing strong support to the theory of
stellar degeneracy. Our analysis also allows us to identify 15 stars
that are better interpreted in terms of unresolved double degenerate
binaries. Atmospheric parameters for both components in these binary
systems are obtained using a novel approach. We further identify a few
white dwarfs that are possibly composed of an iron core rather than a
carbon/oxygen core, since they are consistent with Fe-core
evolutionary models.
Description:
High S/N spectroscopic observations were gathered for all white dwarfs
in our sample, particularly in the blue portion of the spectrum
(λ∼3700-5200Å), to cover the hydrogen Balmer line series and
most of the important neutral helium lines, but we also secured
spectra at Hα to constrain the hydrogen abundance in DB stars.
Most of the spectroscopic data for DA and DB stars were retrieved from
our previous white dwarf studies (Bergeron+ 1992ApJ...394..228B 1992ApJ...394..228B ;
Liebert+ 2005, J/ApJS/156/47 ; Subasavage+ 2007, J/AJ/134/252 ;
2008AJ....136..899S 2008AJ....136..899S ; 2009AJ....137.4547S 2009AJ....137.4547S ; Bergeron+ 2011ApJ...737...28B 2011ApJ...737...28B ;
Gianninas+ 2011, J/ApJ/743/138 ; Giammichele+ 2012ApJS..199...29G 2012ApJS..199...29G ;
Limoges+ 2015, J/ApJS/219/19); the spectral resolution in all cases
ranges from 2 to 9Å FWHM. We also make use of high-resolution
(<1Å FWHM) observations from the ESO SN Ia Progenitor Survey (SPY;
Napiwotzki+ 2003Msngr.112...25N 2003Msngr.112...25N).
For each object in our sample, we searched the literature for several
sets of photometric data, namely, Johnson BVRI, SDSS ugriz, and
Stromgren uvby photometry in the optical, as well as Johnson JHK and
2MASS JHKs photometry in the infrared. See section 2.4 for the details.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 97 158 Adopted physical parameters of white dwarfs with
reliable data
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See also:
B/wd : Spectroscopically identified white dwarfs (McCook+, 2014)
J/AJ/154/32 : Solar neighborhood. XXXIX. Nearby WDs (Subasavage+, 2017)
J/A+A/583/A86 : DB white dwarfs in SDSS DR10 and DR12 (Koester+, 2015)
J/ApJS/219/19 : Census of nearby white dwarfs from SUPERBLINK (Limoges+, 2015)
J/MNRAS/446/4078 : New white dwarf stars in SDSS DR10 (Kepler+, 2015)
J/AJ/147/129 : White dwarfs within 25pc of the Sun (Sion+, 2014)
J/ApJ/743/138 : Spectroscopic survey of bright white dwarfs (Gianninas+, 2011)
J/ApJ/730/128 : Spectroscopy of DA WD from the SDSS-DR4 (Tremblay+, 2011)
J/MNRAS/403/1949 : UBV(RcIc)JHK photometry of HIP nearby stars (Koen+, 2010)
J/ApJ/712/585 : Apparent velocity measurements of DA WDs (Falcon+, 2010)
J/A+A/505/441 : UVES/VLT spectra of white dwarfs (Koester+, 2009)
J/AJ/135/1239 : Spectral distances to DA white dwarfs (Holberg+, 2008)
J/A+A/470/1079 : UVES/VLT spectroscopy of white dwarfs (Voss+, 2007)
J/ApJ/663/1291 : DZ stars in SDSS DR4 (Dufour+, 2007)
J/ApJ/657/1013 : IR photometry of 2MASS/Spitzer white dwarfs (Tremblay+, 2007)
J/AJ/134/252 : New nearby white dwarf systems (Subasavage+, 2007)
J/AJ/132/1221 : VJHK and SDSS photometry of DA white dwarfs (Holberg+, 2006)
J/ApJS/161/394 : Low-luminosity companions to white dwarfs (Farihi+, 2005)
J/ApJS/156/47 : DA white dwarfs from the Palomar Green Survey (Liebert+, 2005)
J/ApJ/631/1100 : Atmospheric parameters of DA white dwarfs (Gianninas+, 2005)
J/ApJS/133/413 : BVRIJHK photometry of cool white dwarfs (Bergeron+, 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- WD White Dwarf identifier (HHMM+DDd; B1950)
11- 24 A14 --- Name Common name
26- 30 A5 --- SpT WD spectral type
32- 37 F6.2 pc Dist [2.6/216] Parallactic distance Dπ
39- 43 F5.2 pc e_Dist [0.01/35] Uncertainty in Dist
45- 49 I5 K Teff [6354/67133] Effective temperature
51- 54 I4 K e_Teff [61/3225] Uncertainty in Teff
56 A1 --- f_Teff Method code for determining Teff
(S=spectroscopic or P=photometric)
58- 61 F4.2 [cm/s2] log(g) [7.3/9.4] log surface gravity
63- 66 F4.2 [cm/s2] e_log(g) [0.04/0.3] Uncertainty in log(g)
68- 73 F6.4 Rsun Rad [0.003/0.03] Photometric technique
derived radius (Rπ)
75- 80 F6.4 Rsun e_Rad [0.0001/0.005] Uncertainty in Rad
82- 85 F4.2 Msun Mass [0.2/4] Mass from log(g) and Radius
87- 90 F4.2 Msun e_Mass [0.05/1.4] Uncertainty in Mass
92- 95 F4.2 --- Delta [0.01/9.5] Difference between distance
measurements (1)
97 I1 --- Note [1/3]? Additional note (2)
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Note (1): We also give, as a quantitative measure of consistency with the
C/O-core mass-radius relation, the difference between the parallactic
distance and the mass-radius relation derived distance, in
units of σ.
Note (2): Note as follows:
1 = Unresolved double degenerate system. The parameters derived under
the assumption of a single star are meaningless. Atmospheric
parameters of both components are given in Figure 16.
2 = Weakly magnetic white dwarf.
3 = Possible iron-core white dwarf.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Jun-2018