2005A&A...442..315R


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.07CET15:20:07

2005A&A...442..315R - Astronomy and Astrophysics, volume 442, 315-321 (2005/10-4)

X-rays from α Centauri - The darkening of the solar twin.

ROBRADE J., SCHMITT J.H.M.M. and FAVATA F.

Abstract (from CDS):

We present first results from five XMM-Newton observations of the binary system α Centauri, which has been observed in snapshot like exposures of roughly two hours each during the last two years. In all our observations the X-ray emission of the system is dominated by α Cen B, a K1 star. The derived light curves of the individual components reveal variability on short timescales and a flare was discovered on α Cen B during one observation. A PSF fitting algorithm is applied to the event distribution to determine the brightness of each component during the observations. We perform a spectral analysis with multi-temperature models to calculate the X-ray luminosities. We investigate long term variability and possible activity cycles of both stars and find the optically brighter component α Cen A, a G2 star very similar to our Sun, to have fainted in X-rays by at least an order of magnitude during the observation program, a behaviour never observed before on α Cen A, but rather similar to the X-ray behaviour observed with XMM-Newton on HD 81809. We also compare our data with earlier spatially resolved observations performed over the last 25 years.

Abstract Copyright:

Journal keyword(s): stars: activity - stars: coronae - stars: flare - stars: late-type - X-rays: stars

Simbad objects: 7

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Number of rows : 7

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 81809 SB* 09 27 46.77993 -06 04 16.2822   6.02 5.40     G1.5IV-V 267 0
2 V* V645 Cen Fl* 14 29 42.9451234609 -62 40 46.170818907 14.21 12.95 11.13 9.45 7.41 M5.5Ve 898 0
3 * alf Cen B PM* 14 39 35.06311 -60 50 15.0992 2.89 2.21 1.33     K1V 866 1
4 * alf Cen A SB* 14 39 36.49400 -60 50 02.3737 0.96 0.72 0.01     G2V 1110 0
5 * 61 Cyg A BY* 21 06 53.9396100677 +38 44 57.897024357 7.50 6.39 5.21 4.19 3.54 K5V 931 0
6 * 61 Cyg ** 21 06 53.95 +38 44 57.9           ~ 154 0
7 * 61 Cyg B Fl* 21 06 55.2640651855 +38 44 31.362140913 8.63 7.40 6.03 4.86 3.55 K7V 661 1

    Equat.    Gal    SGal    Ecl

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2019.12.07-15:20:07

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