Chandra observation of an unusually long and intense X-ray flare from a young solar-like star in M 78

Grosso, N.; Montmerle, T.; Feigelson, E. D.; Forbes, T. G.

doi:10.1051/0004-6361:20034070

Cited by 34 publications

(42 citation statements)

References 45 publications

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“…This process is somewhat related to coronal mass ejections (CMEs) from the Sun and is believed to explain the release of giant X-ray flares in YSOs (Grosso et al 2004).…”

Section: Anti-parallel Configuration: "Cme-like Ejecta"mentioning

confidence: 99%

Which jet launching mechanism(s) in T Tauri stars?

Ferreira¹,

Dougados²,

Cabrit

2006

A&A

372

482

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Aims. We examine whether ejection phenomena from accreting T Tauri stars can be described by only one type of self-collimated jet model. Methods. We present analytical kinematic predictions valid soon after the Alfvén surface for all types of steady magnetically selfconfined jets. Results. We show that extended disc winds, X-winds, and stellar winds occupy distinct regions in the poloidal speed vs. specific angular momentum plane. Comparisons with current observations of T Tauri jets yield quantitative constraints on the range of launching radii, magnetic lever arms, and specific energy input in disc and stellar winds. Implications on the origin of jet asymmetries and disc magnetic fields are outlined. Conclusions. We argue that ejection phenomena from accreting T Tauri stars most likely include three dynamical components: (1) an outer self-collimated steady disc wind carrying most of the mass-flux in the optical jet (when present); confining (2) a pressure-driven coronal stellar wind; and (3) a hot inner flow made of blobs sporadically ejected from the magnetopause. If the stellar magnetic moment is parallel to the disc magnetic field, then the highly variable inner flow resembles a "Reconnection X-wind", that has been proven to efficiently brake down an accreting and contracting young star. If the magnetic moment is anti-parallel, then larger versions of the solar coronal mass ejections are likely to occur. The relative importance of these three components in the observed outflows and the range of radii involved in the disc wind are expected to vary with time, from the stage of embedded source to the optically revealed T Tauri star phase.

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“…This process is somewhat related to coronal mass ejections (CMEs) from the Sun and is believed to explain the release of giant X-ray flares in YSOs (Grosso et al 2004).…”

Section: Anti-parallel Configuration: "Cme-like Ejecta"mentioning

confidence: 99%

Which jet launching mechanism(s) in T Tauri stars?

Ferreira¹,

Dougados²,

Cabrit

2006

A&A

372

482

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“…X-ray flares with unusually long rise phases have also been reported (e.g., Grosso et al 2004;Wang et al 2007;Broos et al 2007). …”

Section: X-ray Light Curvesmentioning

confidence: 99%

Observation of enhanced X-ray emission from the CTTS AA Tauri during one transit of an accretion funnel flow

Grosso¹,

Bouvier²,

Montmerle³

et al. 2007

A&A

Self Cite

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Context. Classical T Tauri stars are young solar-type stars accreting material from their circumstellar disks. Thanks to a favorable inclination of the system, the classical T Tauri star AA Tau exhibits periodic optical eclipses as the warped inner disk edge occults the stellar photosphere. Aims. We intend to observe the X-ray and UV emission of AA Tau during the optical eclipses with the aim of localizing these emitting regions on the star. Methods. AA Tau was observed for about 5 h per XMM-Newton orbit (2 days) over 8 successive orbits, which covers two optical eclipse periods (8.22 days). The XMM-Newton optical/UV monitor simultaneously provided UV photometry (UVW2 filter at 206 nm) with a ∼15 min sampling rate. Some V-band photometry was also obtained from the ground during this period in order to determine the dates of the eclipses. Results. Two X-ray and UV measurements were secured close to the center of the eclipse (∆V ∼ 1.5 mag). The UV flux is the highest just before the eclipse starts and the lowest towards the end of it. UV flux variations amount to a few 0.1 mag on a timescale of a few hours and up to 1 mag on a timescale of a week, none of which are correlated with the X-ray flux. We model it with a weekly modulation (inner disk eclipse), plus a daily modulation, which suggests a non-steady accretion, but needs a longer observation to be confirmed. No such eclipses are detected in X-rays. Within each 5 h-long observation, AA Tau has a nearly constant X-ray count rate. On a timescale of days to weeks, the X-ray flux varies by a factor of 2−8, except for one measurement where the X-ray count rate was nearly 50 times higher than the minimum observed level even though photoelectric absorption was the highest at this phase, and the plasma temperature reached 60 MK, i.e. a factor of 2−3 higher than in the other observations. This X-ray event, observed close to the center of the optical eclipse, is interpreted as an X-ray flare. Conclusions. We explain the variable column density with the low-density accretion funnel flows blanketing the magnetosphere. The lack of X-ray eclipses indicates that X-ray emitting regions are located at high latitudes. Furthermore, the occurrence of a strong X-ray flare near the center of the optical eclipse suggests that the magnetically active areas are closely associated with the base of the high-density accretion funnel flow. We speculate that the impact of this free-falling accretion flow onto the strong magnetic field of the stellar corona may boost the X-ray emission.

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“…We derived the flaring loops semi-length finding that these sizes were slightly smaller than the stellar radius (L ∼ 0.7−0.8 R ) in three cases, while in the last case the flare originated in a compact loop with semi-length of L ∼ 0.1 R . These results are supported by studies of X-ray flares performed adopting different methods (Favata et al 2001;Imanishi et al 2003;Grosso et al 2004). As a result, coronal loops longer than the stellar radius, such as those found in the Orion nebula cluster by Favata et al (2005), are rare and/or present only in the very early stages of stellar evolution.…”

Section: Short Term X-ray Variabilitymentioning

confidence: 58%

XMM-Newton survey of two upper Scorpius regions

Argiroffi

Favata

Flaccomio

et al. 2006

A&A

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Aims. We studied X-ray emission from young stars by analyzing the deep XMM-Newton observations of two regions of the Upper Scorpius association with an age of 5 Myr. Methods. Based on near infrared and optical photometry we identified 22 Upper Scorpius photometric members among the 224 detected X-ray sources. We derived coronal properties of Upper Scorpius stars by performing X-ray spectral and timing analyses. The study of four strong and isolated stellar flares allowed us to derive the length of the flaring loops. Results. Among the 22 Upper Scorpius stars, 13 were identified as Upper Scorpius photometric members for the first time. The sample includes 7 weak-line T Tauri stars and 1 classical T Tauri star, while the nature of the remaining sources is unknown. Except for the intermediate mass star HD 142578, all the detected USco sources are low-mass stars of spectral types ranging from G to late M. The X-ray emission spectrum of the most intense Upper Scorpius sources indicates metal depleted plasma with temperature of ∼10 MK, resembling the typical coronal emission of active main sequence stars. At least 59% of the detected members of the association have variable X-ray emission, and the flaring coronal structures appear shorter than or comparable to the stellar radii already at the Upper Scorpius age. We also found indications of increasing plasma metallicity (up to a factor 20) during strong flares. We identified a new galaxy cluster among the 224 X-ray source detected: the X-ray spectrum of its intra cluster medium indicates a redshift of ∼0.41 ± 0.02.

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Chandra observation of an unusually long and intense X-ray flare from a young solar-like star in M 78

Cited by 34 publications

References 45 publications

Which jet launching mechanism(s) in T Tauri stars?

Which jet launching mechanism(s) in T Tauri stars?

Observation of enhanced X-ray emission from the CTTS AA Tauri during one transit of an accretion funnel flow

XMM-Newton survey of two upper Scorpius regions

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