J/A+A/475/677 X-ray emission from A-type stars (Schroeder+, 2007)
X-ray emission from A-type stars.
Schroeder C., Schmitt J.H.M.M.
<Astron. Astrophys., 475, 677-684 (2007)>
=2007A&A...475..677S 2007A&A...475..677S
ADC_Keywords: Stars, A-type ; X-ray sources
Keywords: X-rays: stars - stars: activity - stars: coronae - stars: general
Abstract:
Being fully radiative, stars of spectral type A are not expected to
harbor magnetic dynamos and hence such stars are not expected to
produce X-ray emission. Indeed, while the X-ray detection rate of such
stars in X-ray surveys is low, it is not zero and some of the brighter
A-type stars have been detected on different occasions and with
different instruments. To study systematically the puzzle of the X-ray
emitting A-type stars, we carried out an X-ray study of all A-type
stars listed in the Bright Star Catalogue using the ROSAT public data
archive. We found a total of 312 bright A-type stars positionally
associated with ROSAT X-ray sources; we analyzed the X-ray light
curves as well as searched for evidence of RV variations to identify
possible late-type companions producing the X-ray emission. In this
paper we present a list of X-ray active A-type stars, including the
collected data about multiplicity, X-ray luminosity and spectral
peculiarities.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 100 84 List of X-ray associated "bona fide" single or
resolved multiple A-type stars
table3.dat 102 226 List of X-ray associated A-type stars in binary
or multiple systems or with hints of hidden
companions
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
IX/28 : ROSAT HRI Pointed Observations (1RXH) (ROSAT Team, 2000)
III/135 : Henry Draper Catalogue and Extension (Cannon+ 1918-1924; ADC 1989)
Byte-by-byte Description of file: table[23].dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- HR HR number, from the Bright Star Catalog V/50
6- 7 A2 --- Bin Binarity flag (1)
9- 11 I3 km/s vsini ? Rotational velocity or lower value of
rotational velocity when interval
12 A1 --- --- [-]
13- 15 I3 km/s vsiniu ? Upper value of rotational velocity
when interval
17 A1 --- l_Sep Limit flag on Sep
18- 25 F8.4 arcsec Sep ? Separation for visual binary systems
27 A1 --- --- [/+]
28- 32 F5.1 arcsec Sep2 ? Second value of separation for visual binary
systems
33- 34 A2 --- n_Sep2 Note on Separation values
36- 40 F5.1 mag Dmag ? Difference in the magnitude between the
star and its closest companion
41 A1 --- --- [/+]
42- 45 F4.1 mag Dmag2 ? Second value of difference in the magnitude
between the A star and its closest companion
46- 51 A6 --- n_Dmag Additional informations on Dmag
52- 67 A16 --- SpType MK spectral types of the components
69- 72 I4 pc Dist ?=- Distance of the star as given by Hipparcos
(Cat. I/239) parallaxes
74- 76 A3 --- Obs Catalog flag indicating in which observation
mode the star has been observed (2)
78- 84 F7.5 ct/s CR Count rate of the associated X-ray source (3)
86- 92 F7.5 ct/s e_CR ?=0.0 Error of the count rate (4)
94-100 F7.1 10+20W LX ?=- X-ray luminosity (5)
102 I1 --- Notes [1/3]? Notes (6)
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Note (1): Binary flag as follows:
S = single star
B = visual or eclipsing binary
SB = spectroscopic binary
PB = potential binary
Note (2): Flags as follows:
R = ROSAT all-sky survey
P = PSPC pointing
H = HRI pointing
Note (3): First choice were PSPC pointing source data, second HRI and third
survey observation data.
Note (4): Errors with a value of 0.0 mark sources with flags in the ROSAT
catalogs that indicate a suspect source or false detection in the
field.
Note (5): X-ray luminosity derived from the distance as given in Col. 7
and the count rates as given in Col. 9. The values are given in units
of 1027erg/s (1020W).
Note (6): Individual notes as follows:
1 = Simon et al. (1995PASP..107.1034S 1995PASP..107.1034S) calculate an Lx of
33x1027erg/s from PSPC pointing observations. The Second
ROSAT Source Catalog of Pointed Observation (2001) lists false
detections in the field and therefor no count rate for the source.
2 = In The Second ROSAT Source Catalog of Pointed Observation (2001)
this source is flagged as suspect in lightcurve, variability
and spectrum. No count rate for the source is listed.
3 = See Zinnecker & Preibisch (1994A&A...292..152Z 1994A&A...292..152Z) and
Hamaguchi et al. (2005ApJ...618..360H 2005ApJ...618..360H).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 31-Dec-2007