J/MNRAS/399/699Parameters of atmospheres of white dwarfs (Mortlock+, 2009)

Photometric constraints on white dwarfs and the identification of extreme objects. Mortlock D.J., Peiris H.V., Ivezic Z. <Mon. Not. R. Astron. Soc., 399, 699-714 (2009)> =2009MNRAS.399..699M (SIMBAD/NED BibCode)ADC_Keywords: Stars, white dwarf ; Models, atmosphereKeywords: methods: statistical - surveys - white dwarfsAbstract: It is possible to reliably identify white dwarfs (WDs) without recourse to spectra, instead using photometric and astrometric measurements to distinguish them from main-sequence stars and quasars. WDs' colours can also be used to infer their intrinsic properties (effective temperature, surface gravity, etc.), but the results obtained must be interpreted with care. The difficulties stem from the existence of a solid angle degeneracy, as revealed by a full exploration of the likelihood, although this can be masked if a simple best-fitting approach is used. Conversely, this degeneracy can be broken if a Bayesian approach is adopted, as it is then possible to utilize the prior information on the surface gravities of WDs implied by spectroscopic fitting. The benefits of such an approach are particularly strong when applied to outliers, such as the candidate halo and ultracool WDs identified by Vidrih et al. A reanalysis of these samples confirms their results for the latter sample, but suggests that most of the halo candidates are thick-disc WDs in the tails of the photometric noise distribution.File Summary:

FileName Lrecl Records Explanations

ReadMe 80 . This file table1.dat 92 34 *Estimated H atmosphere model parameters of the 34 V07 candidate halo WDs, obtained using the informative prior defined in Eq. (9) table2.dat 92 34 *Estimated He atmosphere model parameters of the 34 V07 candidate halo WDs, obtained using the informative prior defined in Eq. (9) table3.dat 104 34 Model selection quantities for the 34 V07 candidate halo WDs table4.dat 48 20 *Estimated model parameters of the 17 V07 candidate halo WDs with spectroscopic fits presented by Eisenstein et al. (2006, Cat. J/ApJS/167/40) table5.dat 92 24 *Estimated H atmosphere model parameters of the 24 V07 candidate ultra-cool WDs, obtained using the informative prior defined in Eq. (9) table6.dat 92 24 *Estimated He atmosphere model parameters of the 24 V07 candidate ultra-cool WDs, obtained using the informative prior defined in Eq. (9) table7.dat 104 24 Model selection quantities for the 24 V07 candidate ultra-cool WDs

Note on table1.dat, table2.dat, table5.dat, table6.dat: obtained using the informative prior defined in Eq. (9), Eq (9): PI(g, Teff,D)=PI(g)PI(Teff)PI(D), i.e., the reduced prior is separable.Note on table4.dat: Three WDs, SDSS J024837.53-003123.9, SDSS J024837.53-003123.9 and SDSS J234110.13+003259.5, were observed twice.

See also: J/ApJS/167/40 : SDSS4 confirmed white dwarfs catalog (Eisenstein+, 2006)Byte-by-byte Description of file: table[15].dat

Bytes Format Units Label Explanations

1- 4 A4 --- --- [SDSS] 6- 24 A19 --- SDSS SDSS name (JHHMMSS.ss+DDMMSS+s) 26- 32 E7.3 K Te(H) Effective temperature for H atmopshere 34- 40 E7.3 K e_Te(H) rms uncertainty on Teff 42- 45 F4.2 [cm/s2] logg(H) Surface gravity for H atmopshere 47- 50 F4.2 [cm/s2] e_logg(H) rms uncertainty on logg 52- 55 F4.2 Msun M(H) Mass for H atmopshere 57- 60 F4.2 Msun e_M(H) rms uncertainty on Mass 62- 69 E8.3 yr Age(H) Age for H atmopshere 71- 78 E8.3 yr e_Age(H) rms uncertainty on Age 80- 82 I3 pc r(H) Distance for H atmopshere 84- 85 I2 pc e_r(H) rms uncertainty in r(H) 87- 89 I3 km/s Vt(H) Tangential velocity for H atmopshere 91- 92 I2 km/s e_Vt(H) rms uncertainty on Vtan

Byte-by-byte Description of file: table[26].dat

Bytes Format Units Label Explanations

1- 4 A4 --- --- [SDSS] 6- 24 A19 --- SDSS SDSS name (JHHMMSS.ss+DDMMSS+s) 26- 32 E7.3 K Te(He) Effective temperature for He atmosphere 34- 40 E7.3 K e_Te(He) rms uncertainty on Teff 42- 45 F4.2 [cm/s2] logg(He) Surface gravity for He atmosphere 47- 50 F4.2 [cm/s2] e_logg(He) rms uncertainty on logg 52- 55 F4.2 Msun M(He) Mass for He atmosphere 57- 60 F4.2 Msun e_M(He) rms uncertainty on Mass 62- 69 E8.3 yr Age(He) Age for He atmosphere 71- 78 E8.3 yr e_Age(He) rms uncertainty on Age 80- 82 I3 pc r(He) Distance for He atmosphere 84- 85 I2 pc e_r(He) rms uncertainty in r(He) 87- 89 I3 km/s Vt(He) Tangential velocity for He atmosphere 91- 92 I2 km/s e_Vt(He) rms uncertainty on Vtan

Byte-by-byte Description of file: table[37].dat

Bytes Format Units Label Explanations

1- 4 A4 --- --- [SDSS] 6- 24 A19 --- SDSS SDSS name (JHHMMSS.ss+DDMMSS+s) 26- 29 F4.2 [cm/s2] gb(H) Best-fit log g values estimated using the uninformative g prior for H (1) 31- 34 F4.2 [cm/s2] gb(He) Best-fit log g values estimated using the uninformative g prior for He (1) 36- 40 F5.1 --- chi2(H) Miminum chi^{2}value for H 42- 46 F5.1 --- chi2(He) Miminum chi^{2}value for He 48- 54 E7.2 --- Ev(H) Evidence value for H (2) 56- 62 E7.2 --- Ev(He) Evidence value for He (2) 64- 70 E7.4 --- Pr(H) Probability that the WD atmosphere is H 72-104 A33 --- Notes Indicates whether the model selection result is driven by the data, the informative g prior, or the 10:1 model prior

Note (1): UKIDSS data have been used where availableNote (2): Evidence is the integral over the Np model parameters.

Byte-by-byte Description of file: table4.dat

Bytes Format Units Label Explanations

1- 4 A4 --- --- [SDSS] 6- 24 A19 --- SDSS SDSS name (JHHMMSS.ss+DDMMSS+s) 26- 27 A2 --- Type WD type 29- 32 F4.2 [cm/s2] logg Surface gravity 34- 37 F4.2 [cm/s2] e_logg rms uncertainty on logg 39- 43 I5 K Teff Effective temperature 45- 48 I4 K e_Teff rms uncertainty on Teff

History: From electronic version of the journal(End)Patricia Vannier [CDS] 09-Mar-2010

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