J/MNRAS/454/28 Bayesian statistics for massive stars (Mugnes+, 2015)
Bayesian statistics as a new tool for spectral analysis.
I. Application for the determination of basic parameters of massive stars.
Mugnes J.-M., Robert C.
<Mon. Not. R. Astron. Soc., 454, 28-52 (2015)>
=2015MNRAS.454...28M 2015MNRAS.454...28M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, B-type ; Effective temperatures ; Rotational velocities
Keywords: methods: data analysis - methods: statistical -
techniques: spectroscopic - stars: atmospheres - stars: massive -
stars: rotation
Abstract:
Spectral analysis is a powerful tool to investigate stellar properties
and it has been widely used for decades now. However, the methods
considered to perform this kind of analysis are mostly based on
iteration among a few diagnostic lines to determine the stellar
parameters. While these methods are often simple and fast, they can
lead to errors and large uncertainties due to the required
assumptions. Here, we present a method based on Bayesian statistics to
find simultaneously the best combination of effective temperature,
surface gravity, projected rotational velocity, and microturbulence
velocity, using all the available spectral lines. Different tests are
discussed to demonstrate the strength of our method, which we apply to
54 mid-resolution spectra of field and cluster B stars obtained at the
Observatoire du Mont-Megantic. We compare our results with those
found in the literature. Differences are seen which are well explained
by the different methods used. We conclude that the B-star
microturbulence velocities are often underestimated. We also confirm
the trend that B stars in clusters are on average faster rotators than
field B stars.
Description:
We use our spectral analysis method based on Bayesian statistics that
simultaneously constrains four stellar parameters (effective
temperature, surface gravity, projected rotational velocity, and
microturbulence velocity) on a sample of B stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 63 56 List of studied stars
tableb.dat 137 297 Basic parameters of field and cluster B stars
(tables B1-B11 of the paper)
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See also:
J/ApJ/648/591 : Stellar rotation in young clusters. II. (Huang+, 2006)
J/ApJ/648/580 : Rotational velocities in 19 open clusters (Huang+, 2006)
J/AJ/134/1570 : Rotational velocities of OB stars (Daflon+, 2007)
J/ApJ/722/605 : A stellar rotation census of B stars (Huang+, 2010)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Cluster Cluster name or Field for field stars
9- 19 A11 --- Star Star name
21- 22 I2 h RAh Simbad right ascension (J2000)
24- 25 I2 min RAm Simbad right ascension (J2000)
27- 31 F5.2 s RAs Simbad right ascension (J2000)
33 A1 --- DE- Declination sign (J2000)
34- 35 I2 deg DEd Declination (J2000)
37- 38 I2 arcmin DEm Declination (J2000)
40- 43 F4.1 arcsec DEs Declination (J2000)
45- 63 A19 --- SName Simbad name
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Byte-by-byte Description of file: tableb.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Table Original table number (1)
5- 11 A7 --- Cluster Cluster name or Field for field stars
13- 23 A11 --- Star Star name
25- 29 I5 K Teff Effective temperature
30 A1 --- --- [+]
31- 33 I3 K E_Teff ? Upper value of Teff error
34 A1 --- --- [-]
35- 38 I4 K e_Teff ? rms uncertainty ion Tefff or
lower value of Teff error
40- 44 F5.3 [cm/s2] logg Surface gravity
45 A1 --- --- [+]
46- 49 F4.2 [cm/s2] E_logg ? Upper value of logg error
50 A1 --- --- [-]
51- 55 F5.3 [cm/s2] e_logg ? rms uncertainty on logg
or lower value of logg error
57- 59 I3 km/s vsini Rotational velocity
60 A1 --- --- [+]
61- 62 I2 km/s E_vsini ? Upper value of vsini error
63 A1 --- --- [-]
64- 65 I2 km/s e_vsini ?=- rms uncertainty on vsini
or lower value of vsini error
67- 70 F4.1 km/s vturb Microturbulent velocity
71 A1 --- --- [+]
72- 74 F3.1 km/s E_vturb ? Upper value of vtur error
75 A1 --- --- [-]
76- 79 F4.1 km/s e_vturb ? rms uncertainty on vturb
or lower value of vtur error
81- 85 A5 --- Ref Reference (2)
88- 89 A2 --- El1 Name of element
90- 96 F7.3 [-] log(El1/H)+12 ? Abundance, log(El1/H)+12
98- 99 A2 --- El2 Name of element
101-104 F4.2 [-] log(El2/H)+12 ? Abundance, log(El2/H)+12
106-107 A2 --- El3 Name of element
108-112 F5.2 [-] log(El3/H)+12 ?=- Abundance, log(El3/H)+12
114-117 F4.2 -- Eps(C) ? C abundance
119-122 F4.2 -- Eps(N) ? N abundance
124-127 F4.2 -- Eps(O) ? O abundance
129-132 F4.2 -- Eps(Mg) ?=- Mg abundance
134-137 F4.2 -- Eps(Si) ? Si abundance
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Note (1): Table number as follows:
B1 = field B stars. 1: spectrum with an effective resolution of 0.9Å
B2 = cluster B stars
B3 = field B stars with modified He and Si abundances from
Lefever et al. (2010A&A...515A..74L 2010A&A...515A..74L)
B4 = field B stars with modified O and Ne abundances from
Takeda et al. (2010PASJ...62.1239T 2010PASJ...62.1239T)
B5 = field B stars with modified C, N, O abundances from
Searle et al. (2008A&A...481..777S 2008A&A...481..777S)
B6 = field B stars with modified He and Si abundances from
Markova & Puls (2008A&A...478..823M 2008A&A...478..823M)
B7 = field B stars with modified C, N, O, Mg, Al, and Si abundances from
Daflon et al. (2007, Cat. J/AJ/134/1570)
B8 = field B stars with modified He and Mg abundances from
Lyubimkov et al. (2005MNRAS.358..193L 2005MNRAS.358..193L)
B9 = field B stars with modified C and N abundances from
Andrievsky et al. (1999A&A...350..598A 1999A&A...350..598A)
B10 = field B stars returned by ATLAS9 with solar composition from
Grevesse & Sauval (1998, Space Sci. Rev., 85, 161)
B11 = cluster B stars returned by ATLAS9 with solar composition from
Grevesse & Sauval (1998, Space Sci. Rev., 85, 161)
Note (2): References as follows:
TW = This Work using models from TLUSTY with the solar composition from
Asplund et al. (2009, ARA&A, 47, 481)
TWHg = This Work using Hγ only
HG10 = Huang et al. (2010, Cat. J/ApJ/722/605)
LEF10 = Lefever et al. (2010A&A...515A..74L 2010A&A...515A..74L)
TAK10 = Takeda et al. (2010PASJ...62.1239T 2010PASJ...62.1239T)
SEA08 = Searle et al. (2008A&A...481..777S 2008A&A...481..777S)
MAR08 = Markova & Puls (2008A&A...478..823M 2008A&A...478..823M)
DAF07 = Daflon et al. (2007, Cat. J/AJ/134/1570)
HG06 = Huang & Gies (2006, Cat. J/ApJ/648/580 and Cat. J/ApJ/648/591)
LYU05 = Lyubimkov et al. (2005MNRAS.358..193L 2005MNRAS.358..193L)
AND99 = Andrievsky et al. (1999A&A...350..598A 1999A&A...350..598A)
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(End) Patricia Vannier [CDS] 23-Jun-2016