2008A&A...484..479S


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST15:55:32

2008A&A...484..479S - Astronomy and Astrophysics, volume 484, 479-486 (2008/6-3)

Magnetic fields in A-type stars associated with X-ray emission.

SCHROEDER C., HUBRIG S. and SCHMITT J.H.M.M.

Abstract (from CDS):

A common explanation for the observed X-ray emission of A-type stars is the presence of a hidden late-type companion. While this assumption can be shown to be correct in some cases, a number of lines of evidence suggests that low-mass companions cannot be the correct cause for the observed activity in all cases. A model explains the X-ray emission for magnetic Ap/Bp stars, focusing on the A0p star IQ Aur. In this paper we test whether this theoretical model is able to explain the observed X-ray emission. We present the observations of 13 A-type stars that have been associated with X-ray emission detected by ROSAT. To determine the mean longitudinal magnetic field strength we measured the circular polarization in the wings of the Balmer lines using FORS1. Although the emission of those objects that possess magnetic fields fits the prediction of the Babel and Montmerle model, not all X-ray detections are connected to the presence of a magnetic field. Additionally, the measured magnetic fields do not correlate with the X-ray luminosity. Accordingly, the magnetically confined wind shock model cannot explain the X-ray emission from all the presented stars.

Abstract Copyright:

Journal keyword(s): stars: magnetic fields - stars: activity - X-rays: stars - stars: early-type

Simbad objects: 23

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Number of rows : 23

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 HD 31648 Ae* 04 58 46.2654165113 +29 50 36.990341242 7.84 7.78 7.62 7.76 7.43 A5Vep 394 0
2 V* IQ Aur a2* 05 19 00.0284977265 +33 44 54.237390018   5.201 5.371     A0p 269 0
3 * tet01 Ori C ** 05 35 16.46375 -05 23 22.8486 4.20 5.15 5.13 4.91 4.73 O7Vp 1272 1
4 * sig Ori E Y*O 05 38 47.2050001416 -02 35 40.514907495 5.66 6.38 6.46 6.84 7.08 B2IV-Vp_He 400 0
5 * zet Pup BY* 08 03 35.04754 -40 00 11.3321 0.89 1.98 2.25 2.36 2.58 O4I(n)fp 1091 1
6 V* HR Lup a2* 15 08 12.1245697358 -40 35 02.158712447 5.25 5.65 5.79     B8IVSi 150 1
7 * alf CrB Al* 15 34 41.26800 +26 42 52.8940 2.19 2.22 2.24 2.21 2.25 A1IV 455 0
8 NAME ASSOC II SCO As* 16 15 -24.2           ~ 1120 1
9 * omi Sco V* 16 20 38.1806792 -24 10 09.549111 5.99 5.40 4.57 3.69 2.93 A4II/III 240 0
10 * ome Oph a2* 16 32 08.1998273 -21 27 59.012005 4.69 4.56 4.45 4.32 4.30 ApSrEuCr 144 0
11 * sig Ara * 17 35 39.5895684 -46 30 20.461748 4.47 4.56 4.59 4.60 4.65 A0V 60 0
12 HD 159312 * 17 35 43.0772875993 -37 26 23.541061418   6.493 6.463     A0V 27 0
13 HD 163336 PM* 17 56 19.0352937873 -15 48 45.099719932   5.967 5.929     A0V 49 0
14 HD 172555 PM* 18 45 26.9004853 -64 52 16.539796   4.967 4.767     A7V 234 0
15 HD 174240 * 18 49 37.1930973154 +00 50 10.301579638   6.257 6.226     A1IV 40 0
16 HD 182761 * 19 25 22.3916545864 +20 16 18.213014023   6.278 6.287     A0V 55 0
17 HD 186219 * 19 49 25.3003438226 -72 30 12.164514365   5.628 5.392     A4IV 59 0
18 * gam Equ a2* 21 10 20.5001160337 +10 07 53.682085548 5.03 4.94 4.68 4.43 4.32 A9VpSrCrEu 513 0
19 V* GL Lac a2* 22 44 07.5047921489 +55 35 21.208257555   8.85 8.81     A0p 261 0
20 * eps Gru SB* 22 48 33.2983075490 -51 19 00.732184713   3.556 3.466     A2IVn 117 0
21 HD 217186 PM* 22 58 42.6247554010 +07 20 24.289855998   6.385 6.340     A1V 34 0
22 HD 224361 ** 23 57 19.9059187242 -62 57 23.746643231   6.042 5.943     A1IV 29 0
23 * eta Tuc ** 23 57 35.0785168096 -64 17 53.622899148   5.046 4.989     A1V 79 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-15:55:32

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