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

Abstract

Methods: 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. Results: 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 L_x = 1.0 x 10^26 erg/s in the 0.2-2.0 keV band. The corresponding activity level of log L_x/L_bol = -4.1 points to a moderately active star. Altogether, X-ray activity from very low-mass stars shows similar trends to more massive stars, despite their different interior structure. 1RXSJ115928.5-524717 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 rather X-ray active, implying the existence of an efficient dynamo mechanisms that is capable of creating magnetic activity and coronal X-ray emission.

arXiv commentaccepted by A&A, 6 pages, 3 figures

References in corpus (15)

• Evolutionary models for very-low-mass stars and brown dwarfs with dusty atmospheres
• Theory of Low-Mass Stars and Substellar Objects
• New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence
• Rotation and Activity in Mid-M to L Dwarfs
• The First Direct Measurements of Magnetic Fields on Very Low-Mass Stars
• Activity and Kinematics of Ultracool Dwarfs Including An Amazing Flare Observation
• Flaring Up All Over -- Radio Activity in Rapidly-Rotating Late-Type M and L Dwarfs
• High resolution spectroscopy of ultracool M dwarfs
• Discovery of new nearby L and late-M dwarfs at low Galactic latitude from the DENIS database
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. II. Mixed Trends in VB10 and LSR1835+32 and the Possible Role of Rotation
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. I. The Complex Behavior of the M8.5 Dwarf TVLM513-46546
• Simultaneous optical and X-ray observations of a giant flare on the ultracool dwarf LP412-31
• A Chandra X-ray detection of the L dwarf binary Kelu-1: Simultaneous Chandra and Very Large Array observations
• A new strongly X-ray flaring M9 dwarf in the solar neighborhood
• Quiescent X-ray emission from the M9 dwarf LHS 2065

Cited by in corpus (12)

• The stellar activity-rotation relationship and the evolution of stellar dynamos
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. III. X-ray, Radio, and H-alpha Activity Trends in M and L Dwarfs
• Astrometric planet search around southern ultracool dwarfs I: First results, including parallaxes of 20 M8-L2 dwarfs
• Trends in Ultracool Dwarf Magnetism. II. The Inverse Correlation Between X-ray Activity and Rotation as Evidence for a Bimodal Dynamo
• Magnetic Field Topology in Low-Mass Stars: Spectropolarimetric Observations of M Dwarfs
• The ultracool dwarf DENIS-P J104814.7-395606. Chromospheres and coronae at the low-mass end of the main-sequence
• The X-ray source content of the XMM-Newton Galactic Plane Survey
• Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357
• Radio emission in a nearby ultracool dwarf binary: a multi-frequency study
• The Discovery of an X-ray/UV Stellar Flare from the Late-K/Early-M Dwarf LMC 335
• Contemporaneous XMM-Newton investigation of a giant X-ray flare and quiescent state from a cool M-class dwarf in the local cavity
• The first evidence of tidally induced activity in a brown dwarf-M dwarf pair: A Chandra study of the NLTT 41135/41136 system