J/MNRAS/471/3398 Nitrogen abundances for Be and B stars (Ahmed+, 2017)
Rotational mixing in Be stars:
nitrogen abundances for a sample of Be stars from the MiMeS survey.
Ahmed A., Sigut T.A.A.
<Mon. Not. R. Astron. Soc., 471, 3398-3418 (2017)>
=2017MNRAS.471.3398A 2017MNRAS.471.3398A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, B-type ; Stars, Be ; Abundances ; Effective temperatures
Keywords: stars: abundances - stars: atmospheres - stars: rotation -
stars: early-type - circumstellar matter - stars: emission-line, Be
Abstract:
Photospheric nitrogen abundances for a sample of 26 Be stars and 16
normal B stars were found using high-resolution spectra from the
Magnetism in Massive Stars (MiMeS) spectroscopic survey. Nitrogen
abundances were obtained using non-local-thermodynamic-equilibrium
equivalent widths and line profiles, and Monte Carlo simulation was
used to determine the error bounds of the measured nitrogen abundances
due to uncertainties in the adopted stellar parameters, continuum
normalization and atomic data. In addition, the effects of
gravitational darkening and disc contamination on the measured Be star
nitrogen abundances were investigated. About one third of the sample
of Be stars and half of the normal B-type stars have nitrogen
enrichment that may be due to rotational mixing in these rapidly
rotating objects. Corrections for gravitational darkening and disc
contamination do not significantly change the overall results for the
Be star sample. The average nitrogen abundance of the B and Be star
samples coincides with the solar abundance, although the dispersion in
the nitrogen abundances is much larger in the Be star sample. The Be
star sample also has a significant fraction of sub-solar nitrogen
abundance objects that are not present in significant numbers in the B
star sample. This may point to yet unresolved systematic errors in the
analysis of the Be stars.
Description:
The MiMeS survey represents an extensive spectroscopic survey of local
Galactic B-type stars for detecting and classifying magnetic fields in
these objects (Wade et al., 2016MNRAS.456....2W 2016MNRAS.456....2W, Cat. J/MNRAS/456/2).
From the MiMeS survey, two samples of stars were constructed. The
first consists of 26 early-type Be stars with spectral types between
B0 and B3 and luminosity classes between V and II. The second consists
of 16 normal early-type B-type stars, also with spectral types between
B0 and B3 and luminosity classes between V and II.
As part of the MiMeS survey, high-resolution spectra for these stars
were taken with the echelle spectropolarimeter ESPaDOnS on the
Cassegrain focus of the 3.6-m CFHT and the NARVAL spectropolarimeter
on the Telescope Bernard Lyot. ESPaDOnS spectra have a resolving
power of 80000 in the spectroscopic star-only option used for
observing bright stars, and a resolving power of 68000 in the
spectroscopic star + sky mode used for observations of faint stars and
in polarimetric mode in which all Stokes parameters are measured. The
latter mode was adopted in producing the spectra for the MiMeS survey.
ESPaDOnS has a spectral coverage from 3700 to 10500Å in a single
exposure, divided into 40 overlapping orders, with three gaps in the
far red region of the spectrum: 9224-9234Å, 9608-9636Å and
10026-10074Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 87 26 Stellar parameters adopted for the MiMeS
Be star sample
table2.dat 81 16 Stellar parameters adopted for the MiMeS
normal B star sample
table3.dat 105 41 Measured equivalent widths of the NII lines in
the MiMeS Be and B star samples
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See also:
J/A+A/440/305 : Fundamental parameters of fast-rotating B stars
(Fremat+, 2005)
J/MNRAS/371/252 : Southern B and Be stars (Levenhagen+, 2006)
J/A+A/501/297 : Effective temperatures of B Supergiants (Zorec+, 2009)
J/A+A/539/A143 : Nearby B-stars stellar parameters and abundances
(Nieva+, 2012)
J/A+A/551/A12 : HD 48977 frequency analysis (Thoul+, 2013)
J/A+A/550/A79 : Hα and Hβ lines of northern Be stars
(Catanzaro, 2013)
J/MNRAS/456/2 : MiMeS survey of magnetism in massive stars (Wade+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD HD number
8- 12 I5 K TeffL Literature effective temperature
14- 17 I4 K e_TeffL rms uncertainty on TeffL
19- 22 F4.2 [cm/s2] loggL ? Literature surface gravity
24- 27 F4.2 [cm/s2] e_loggL ? rms uncertainty on loggL
29- 35 F7.1 K TeffR ? Revised effective temperature
37- 40 F4.2 [cm/s2] loggR ? Revised surface gravity
42- 49 A8 --- SpType Spectral type from SIMBAD (1)
51- 55 F5.1 km/s vsini ? Rotational velocity from Fremat et al.,
2005A&A...440..305F 2005A&A...440..305F, Cat. J/A+A/440/305
57- 60 F4.1 km/s e_vsini ? rms uncertainty on vsini
62- 66 F5.1 km/s vsiniS Rotational velocity from SIMBAD (1)
68 A1 --- u_vsiniT Uncertainty flag on vsiniT
69- 73 F5.1 km/s vsiniT Rotational velocity from TLUSTY
75 A1 --- u_vsiniN Uncertainty flag on vsiniN
76- 80 F5.1 km/s vsiniN Rotational velocity using NII 3995Å line
82- 87 A6 --- Ref Reference for TeffL and loggL (2)
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Note (1): SIMBAD refers to spectral type classifications and vsini estimates
adopted from the SIMBAD data base (Wenger et al., 2000A&AS..143....9W 2000A&AS..143....9W).
Note (2): References as follows:
Tak10 = Takeda et al., 2010PASJ...62.1239T 2010PASJ...62.1239T
F05 = Fremat et al., 2005A&A...440..305F 2005A&A...440..305F, Cat. J/A+A/440/305
H00 = Harmanec, 2000, ASP Conf. Ser. 214, 13
Zor09 = Zorec et al., 2009A&A...501..297Z 2009A&A...501..297Z, Cat. J/A+A/501/297
LL06 = Levenhagen & Leister, 2006MNRAS.371..252L 2006MNRAS.371..252L, Cat. J/MNRAS/371/252
Cat13 = Catanzaro, 2013A&A...550A..79C 2013A&A...550A..79C , Cat. J/A+A/550/A79
Cote96 = Cote et al., 1996A&A...307..184C 1996A&A...307..184C
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD HD number
8- 12 I5 K Teff Effective temperature
14- 17 I4 K e_Teff ? rms uncertainty on Teff
18 A1 --- n_Teff [a] Note on Teff (1)
20- 23 F4.2 [cm/2] logg Surface gravity
25- 28 F4.2 [cm/2] e_logg ? rms uncertainty on logg
29 A1 --- n_logg [a] Note on Teff (1)
31- 32 A2 --- l_vsini [≤] Limit flag on vsini
33- 34 I2 km/s vsini ? Rotational velocity (2)
36 I1 km/s e_vsini ? rms uncertainty on vsini
38- 39 I2 km/s chit ? Micro-turbulent velocity
41 I1 km/s e_chit ? rms uncertainty on chit
43- 44 I2 km/s zeta ? Radial-tangential macroturbulent velocity
46 I1 km/s e_zeta ? rms uncertainty on zeta
48- 55 A8 --- SpType Spectral type
57- 58 I2 km/s vsiniM MiMeS rotational velocity obtained from the
MiMeS project
60- 61 I2 km/s vsiniN Current rotational velocity of the present
study using the NII 3995Å line
63- 65 F3.1 km/s chitC ?=0 Current micro-turbulent velocity
67- 69 F3.1 km/s e_chitC ? rms uncertainty on chitC
71- 81 A11 --- Ref Reference for Teff and logg (3)
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Note (1): a: Current estimates.
Note (2): The vsini estimates are obtained from the same sources as the
effective temperatures and gravities.
Note (3): References as follows:
Nieva12 = Nieva & Przybilla, 2012A&A...539A.143N 2012A&A...539A.143N, Cat. J/A+A/539/A143
Nieva11 = Nieva & Simon-Diaz, 2011A&A...532A...2N 2011A&A...532A...2N
Underhill79 = Underhill, Divan & Burnichon, 1979MNRAS.189..601U 1979MNRAS.189..601U
Lefever10 = Lefever et al., 2010A&A...515A..74L 2010A&A...515A..74L
Thoul13 = Thoul et al., 2013A&A...551A..12T 2013A&A...551A..12T, Cat. J/A+A/551/A12
Hubrig09 = Hubrig et al., 2009AN....330..317H 2009AN....330..317H
Petit11 = Petit, 2011MNRAS.412L..45P 2011MNRAS.412L..45P
Aerts99 = Aerts et al., 1999A&A...343..872A 1999A&A...343..872A
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Sample [Be B] Sample
4- 9 I6 --- HD HD number
10 A1 --- n_HD [a] Note on HD (1)
12- 16 F5.1 0.1pm EW3995 Measured NII equivalent widths at 3995Å
18- 21 F4.1 0.1pm e_EW3995 rms uncertainty on EW3995 (2)
23- 26 F4.1 0.1pm EW4447 ? Measured NII equivalent widths at 4447Å
28- 31 F4.1 0.1pm e_EW4447 ? rms uncertainty on EW4447 (2)
33- 36 F4.1 0.1pm EW4601.5 ? Measured NII equivalent widths at 4601.5Å
38- 41 F4.1 0.1pm e_EW4601.5 ? rms uncertainty on EW4601.5 (2)
43- 47 F5.1 0.1pm EW4607.2 ? Measured NII equivalent widths at 4607.2Å
49- 52 F4.1 0.1pm e_EW4607.2 ? rms uncertainty on EW4607.2 (2)
54- 57 F4.1 0.1pm EW4613.9 ? Measured NII equivalent widths at 4613.9Å
59- 62 F4.1 0.1pm e_EW4613.9 ? rms uncertainty on EW4613.9 (2)
64- 67 F4.1 0.1pm EW4621.4 ? Measured NII equivalent widths at 4621.4Å
69- 72 F4.1 0.1pm e_EW4621.4 ? rms uncertainty on EW4621.4 (2)
74- 78 F5.1 0.1pm EW4630.5 ? Measured NII equivalent widths at 4630.5Å
80- 83 F4.1 0.1pm e_EW4630.5 ? rms uncertainty on EW4630.5 (2)
85- 89 F5.1 0.1pm EW5676 ? Measured NII equivalent widths at 5676Å
91- 94 F4.1 0.1pm e_EW5676 ? rms uncertainty on EW5676 (2)
96-100 F5.1 0.1pm EW5679.6 ? Measured NII equivalent widths at 5679.6Å
102-105 F4.1 0.1pm e_EW5679.6 ? rms uncertainty on EW5679.6 (2)
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Note (1): a: Equivalent widths of the best-fitting non-LTE synthetic profiles
computed for the adopted Teff and logg but allowing the nitrogen abundance
and vsini to vary.
Note (2): The quoted uncertainties are due to the continuum placement.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 26-May-2020