Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357

Robrade, J.; Poppenhaeger, Katja; Schmitt, J. H. M. M.

doi:10.1051/0004-6361/200913603

Cited by 28 publications

(27 citation statements)

References 25 publications

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“…3. L X and L X /L bol vs. spectral type for J0331-27 (flare peak luminosity and upper limit on the quiescent luminosity), compared with the other UCDs for which X-ray data are available (from Stelzer et al 2006aRobrade et al 2010 andGupta et al 2011). In Fig. 3 we put the X-ray emission of J0331-27 in context to that of other UCDs.…”

Section: Discussionmentioning

confidence: 99%

EXTraS discovery of an X-ray superflare from an L dwarf

Luca

Stelzer

Burgasser

et al. 2020

A&A

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We present the first detection of an X-ray flare from an ultracool dwarf of spectral class L. The event was identified in the EXTraS database of XMM-Newton variable sources, and its optical counterpart, J0331-27, was found through a cross-match with the Dark Energy Survey Year 3 release. Next to an earlier four-photon detection of Kelu-1, J0331-27 is only the second L dwarf detected in X-rays, and much more distant than other ultracool dwarfs with X-ray detections (photometric distance of 240 pc). From an optical spectrum with the VIMOS instrument at the VLT, we determine the spectral type of J0331-27 to be L1. The X-ray flare has an energy of E X,F ∼ 2 × 10 33 erg, placing it in the regime of superflares. No quiescent emission is detected, and from 2.5 Msec of XMM-Newton data we derive an upper limit of L x,qui < 10 27 erg/s. The flare peak luminosity (L x,peak = 6.3 × 10 29 erg/s), flare duration (τ decay ≈ 2400 s), and plasma temperature (≈ 16 MK) are similar to values observed in X-ray flares of M dwarfs. This shows that strong magnetic reconnection events and the ensuing plasma heating are still present even in objects with photospheres as cool as ∼ 2100 K. However, the absence of any other flares above the detection threshold of E X,F ∼ 2.5 × 10 32 erg in a total of ∼ 2.5 Ms of X-ray data yields a flare energy number distribution inconsistent with the canonical power law dN/dE ∼ E −2 , suggesting that magnetic energy release in J0331-27 -and possibly in all L dwarfs -takes place predominantly in the form of giant flares.

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Section: Discussionmentioning

confidence: 99%

EXTraS discovery of an X-ray superflare from an L dwarf

Luca

Stelzer

Burgasser

et al. 2020

A&A

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“…All of these targets are known either as flare producing stars or having flare-producing companions (Choi et al 1999;Robinson et al 1999;Tsikoudi & Kellett 2000;Güdel et al 2001;Magee et al 2003;Güdel et al 2004;Trenholme et al 2004;Shkolnik et al 2005;Stelzer et al 2006;Stepanov et al 2006;Watson et al 2006;Pandey & Singh 2008;Robrade et al 2010;Liefke et al 2010;Pillitteri et al 2010;Fuhrmeister et al 2011;Robrade et al 2012;Scandariato et al 2013;Bhatt et al 2014;Pillitteri et al 2014;Bhatt et al 2014;Pandey & Karmakar 2015). Figure 4 shows a typical image of an X-ray flare occurred on LP412-31, by integrating the signal during the whole flare.…”

Section: Qpps In Stellar Flaresmentioning

confidence: 99%

Comparison of Damped Oscillations in Solar and Stellar X-Ray Flares

Cho

Nakariakov

Kim

et al. 2016

ApJ

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We explore the similarity and difference of the quasi-periodic pulsations (QPPs) observed in the decay phase of solar and stellar flares at X-rays. We identified 42 solar flares with pronounced QPPs, observed with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and 36 stellar flares with QPPs, observed with X-ray Multi Mirror Newton observatory (XMM-Newton). The Empirical Mode Decomposition (EMD) method and least-square fit by a damped sine function were applied to obtain the periods (P ) and damping times (τ ) of the QPPs. We found that (1) the periods and damping times of the stellar QPPs are 16.21±15.86 min and 27.21±28.73 min, while those of the solar QPPs are 0.90±0.56 and 1.53±1.10 min, respectively. (2) The ratio of the damping times to the periods (τ /P ) observed in the stellar QPPs (1.69±0.56) are statistically identical to those of solar QPPs (1.74±0.77). (3) The scalings of the QPP damping time with the period are well described by the power law in both solar and stellar cases. The power indices of the solar and stellar QPPs are 0.96±0.10 and 0.98±0.05, respectively. This scaling is consistent with the scalings found for standing slow magnetoacoustic and kink modes in solar coronal loops. Thus, we propose that the underlying mechanism responsible for the stellar QPPs is the natural magnetohydrodynamic oscillations in the flaring or adjacent coronal loops, as in the case of solar flares.

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“…First, Zapatero Osorio et al (2004) gave an uncertainty in ∼50% on their measurement of v sin i. Secondly, Gl 569 B is a spectroscopic binary and we have plotted the mean of the values measured for the two BDs (30 ± 15 and 37 ± 15 km s −1 for Gl 569Ba and Gl 569 Bb, respectively). Two additional UCDs exhibited X-ray flares, SCR 1845-6357 (Robrade et al 2010) and RXS J115928.5-524717 (Robrade & Schmitt 2009), which are plotted in black with asterisks for flares in Fig. 10.…”

Section: Radio Versus X-ray Emissionmentioning

confidence: 99%

The ultracool dwarf DENIS-P J104814.7-395606

Stelzer

Alcalá

Biazzo

et al. 2012

A&A

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Context. Several diagnostics ranging from the radio to the X-ray band are suitable for investigating the magnetic activity of late-type stars. Empirical connections between the emission at different wavelengths place constraints on the nature and efficiency of the emission mechanism and the physical conditions in different atmospheric layers. The activity of ultracool dwarfs, at the low-mass end of the main-sequence, is poorly understood. Aims. We perform a multi-wavelength study of one of the nearest M9 dwarfs, DENIS-P J104814.7-395606 (4 pc), to examine its position within the group of magnetically active ultracool dwarfs, and, in general, advance our understanding of these objects by comparing them to early-M type dwarf stars and the Sun. Methods. We obtained an XMM-Newton observation of DENIS-P J104814.7-395606 and a broad-band spectrum from the ultraviolet to the near-infrared with X-Shooter. From this dataset, we derive the X-ray properties, stellar parameters, kinematics, and the emission-line spectrum tracing chromospheric activity. We integrate these data by compiling the activity parameters of ultracool dwarfs from the literature. Results. Our deep XMM-Newton observation provides the first X-ray detection of DENIS-P J104814.7-395606 (log L x = 25.1), as well as the first measurement of its V band brightness (V = 17.35 mag). The flux-flux relations between X-ray and chromospheric activity indicators are here for the first time extended into the regime of the ultracool dwarfs. The approximate agreement of DENIS-P J104814.7-395606 and other ultracool dwarfs with flux-flux relations for early-M dwarfs suggests that the same heating mechanisms work in the atmospheres of ultracool dwarfs, albeit weaker as judged from their lower fluxes. The observed Balmer decrements of DENIS 1048-3956 are compatible with optically thick plasma in local thermal equilibrium (LTE) at low, nearly photospheric temperature or optically thin LTE plasma at 20 000 K. Describing the decrements with case B recombination requires different emitting regions for Hα and the higher Balmer lines. The high observed Hα/Hβ flux ratio is also poorly fitted by the optically thin models. We derive a similarly high value for the Hα/Hβ ratio of vB 10 and LHS 2065 and conclude that this may be a characteristic of ultracool dwarfs. We add DENIS-P J104814.7-395606 to the list of ultracool dwarfs detected in both the radio and the X-ray band. The Benz-Güdel relation between radio and X-ray luminosity of late-type stars is well-known to be violated by ultracool dwarfs. We speculate on the presence of two types of ultracool dwarfs with distinct radio and X-ray behaviors.

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Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357

Cited by 28 publications

References 25 publications

EXTraS discovery of an X-ray superflare from an L dwarf

EXTraS discovery of an X-ray superflare from an L dwarf

Comparison of Damped Oscillations in Solar and Stellar X-Ray Flares

The ultracool dwarf DENIS-P J104814.7-395606

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