2009A&A...496..229R


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.25CET16:09:41

2009A&A...496..229R - Astronomy and Astrophysics, volume 496, 229-233 (2009/3-2)

X-ray emission from the M9 dwarf 1RXS J115928.5-524717. Quasi-quiescent coronal activity at the end of the main-sequence.

ROBRADE J. and SCHMITT J.H.M.M.

Abstract (from CDS):

X-ray emission is an important diagnostic for studying magnetic activity in presumably fully convective, very low-mass stars with virtually neutral photospheres. We analyse an XMM-Newton observation of 1RXS J115928.5-524717, an ultracool dwarf with spectral type M9, and compare its X-ray properties to those of other similar very late-type stars. We clearly detected 1RXS J115928.5-524717 at soft X-ray energies in all EPIC detectors. Only minor variability was present during the observation and we attribute the X-ray emission to quasi-quiescent activity. The coronal plasma is described well by a two-temperature model at solar metallicity with temperatures of 2 MK and 6 MK and an X-ray luminosity of about LX=1.0x1026erg/s in the 0.2-2.0keV band. The corresponding activity level of logLX/Lbol≃-4.1 points to a moderately active star. Altogether, X-ray activity from very low-mass stars shows similar trends as more massive stars, despite their different interior structure. The nearby star 1RXS J115928.5-524717 is, after LHS 2065, the second ultracool M9 dwarf that emits X-rays at detectable levels in quasi-quiescence. While faint in absolute numbers, both stars are relatively X-ray active, implying an efficient dynamo mechanism that is capable of creating magnetic activity and coronal X-ray emission.

Abstract Copyright:

Journal keyword(s): stars: activity - stars: coronae - stars: individual: 1RXS J115928.5-524717 - stars: low-mass, brown dwarfs - 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 - 2021
#notes
1 LP 412-31 LM* 03 20 59.7107396327 +18 54 22.772041176   20.5 18.881 16.904 14.484 M8V 112 0
2 LP 666-9 LM* 08 53 36.1607609203 -03 29 32.201339067     18.959 16.781 14.487 M9Ve 229 0
3 1RXS J115928.5-524717 LM* 11 59 27.3607245322 -52 47 18.910528784       16.617 14.49 M9Ve 25 0
4 NAME Kelu-1 BD* 13 05 40.1737206066 -25 41 05.830344467         16.85 L2+L3.5 239 0
5 TVLM 513-46 LM* 15 01 08.1871800643 +22 50 02.120480463   21.4 15.09 18.0   M8.5V 148 0
6 VB 8 Er* 16 55 35.2561420232 -08 23 40.752903617   18.7 16.916 14.566 12.24 M7Ve 392 0
7 VB 10 Er* 19 16 57.6103282334 +05 09 01.588675251     17.30     M8V 441 1

    Equat.    Gal    SGal    Ecl

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2021.02.25-16:09:41

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