X-Ray Flare Oscillations Track Plasma Sloshing along Star-disk Magnetic Tubes in the Orion Star-forming Region

Reale, F.; López‐Santiago, J.; Flaccomio, E.; Petralia, Antonino; Sciortino, S.

doi:10.3847/1538-4357/aaaf1f

Cited by 31 publications

(37 citation statements)

References 55 publications

(95 reference statements)

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“…In the following we will, however, use extinction-corrected energies and luminosities. In Ta-ble 1 we report two independent estimates of intervening material: A V , based on spectral types and source photometry from the literature, also listed in Table 1, and the column density of neutral hydrogen N H , estimated by Flaccomio et al (2018) fitting the time-averaged X-ray source spectra with absorbed thermal plasma emission models (with either one or two components). Both estimates suffer from considerable uncertainties.…”

Section: Resultsmentioning

confidence: 99%

“…In Table 1 we list the 78 X-ray flares in our sample (from 65 stars), all with a simultaneous optical and/or mIR counterpart. The first three columns list the Chandra ACIS source number (from Flaccomio et al 2018), the corresponding Mon identifier from Cody et al (2014), and the Chandra observation id (or ids) during which the flare occurred. In Figure 2 we show six representative examples of "good quality" X-ray detected flares, while in Appendix B we show the full sample of lightcurves 3 .…”

Section: Flare Detection and Sample Definitionmentioning

confidence: 99%

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A multi-wavelength view of magnetic flaring from PMS stars

Flaccomio

Micela

Sciortino

et al. 2018

A&A

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Context. Flaring is an ubiquitous manifestation of magnetic activity in low mass stars including, of course, the Sun. Although flares, both from the Sun and from other stars, are most prominently observed in the soft X-ray band, most of the radiated energy is released at optical/UV wavelengths. In spite of decades of investigation, the physics of flares, even solar ones, is not fully understood. Even less is known about magnetic flaring in pre-main sequence (PMS) stars, at least in part because of the lack of suitable multi-wavelength data. This is unfortunate since the energetic radiation from stellar flares, which is routinely observed to be orders of magnitude greater than in solar flares, might have a significant impact on the evolution of circumstellar, planet-forming disks. Aims. We aim at improving our understanding of flares from PMS stars. Our immediate objectives are constraining the relation between flare emission at X-ray, optical, and mid-infrared (mIR) bands, inferring properties of the optically emitting region, and looking for signatures of the interaction between flares and the circumstellar environment, i.e. disks and envelopes. This information might then serve as input for detailed models of the interaction between stellar atmospheres, circumstellar disks and proto-planets. Methods. Observations of a large sample of PMS stars in the NGC 2264 star forming region were obtained in December 2011, simultaneously with three space-borne telescopes, Chandra (X-rays), CoRoT (optical), and Spitzer (mIR), as part of the "Coordinated Synoptic Investigation of NGC2264" (CSI-NGC2264). Shorter Chandra and CoRoT observations were also obtained in March 2008. We analyzed the lightcurves obtained during the Chandra observations (∼300 ks and ∼60 ks in 2011 and 2008, respectively), to detect X-ray flares with an optical and/or mIR counterpart. From the three datasets we then estimated basic flare properties, such as emitted energies and peak luminosities. These were then compared to constrain the spectral energy distribution of the flaring emission and the physical conditions of the emitting regions. The properties of flares from stars with and without circumstellar disks were also compared to establish any difference that might be attributed to the presence of disks. Results. Seventy-eight X-ray flares (from 65 stars) with an optical and/or mIR counterpart were detected. The optical emission of flares (both emitted energy and peak flux) is found to correlate well with, and to be significantly larger than, the X-ray emission. The slopes of the correlations suggest that the difference becomes smaller for the most powerful flares. The mIR flare emission seems to be strongly affected by the presence of a circumstellar disk: flares from stars with disks have a stronger mIR emission with respect to stars without disks. This might be attributed to either a cooler temperature of the region emitting both the optical and mIR flux or, perhaps more likely, to the reprocessing of the optical (and X-ray) flare emission by the...

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Section: Resultsmentioning

confidence: 99%

Section: Flare Detection and Sample Definitionmentioning

confidence: 99%

A multi-wavelength view of magnetic flaring from PMS stars

Flaccomio

Micela

Sciortino

et al. 2018

A&A

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“…The efficient thermal conduction smooths out temperature perturbations in the hot corona, but the pressure fronts drive strong density fronts that periodically accumulate when they are reflected and in turn determine strong alternating excesses and reductions of emission measure which modulate the light curves with long-period and large-amplitude pulsations. Hydrodynamic loop modeling has been able to reproduce long flares showing pulsations with period of hours and amplitude of ∼ 20% observed in the X-rays from protostars in the Orion region (Reale et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Large-amplitude Quasiperiodic Pulsations as Evidence of Impulsive Heating in Hot Transient Loop Systems Detected in the EUV with SDO/AIA

Reale

Testa

Petralia

et al. 2019

ApJ

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Short heat pulses can trigger plasma pressure fronts inside closed magnetic tubes in the corona. The alternation of condensations and rarefactions from the pressure modes drive large-amplitude pulsations in the plasma emission. Here we show the detection of such pulsations along magnetic tubes that brighten transiently in the hot 94Å EUV channel of SDO/AIA. The pulsations are consistent with those predicted by hydrodynamic loop modeling, and confirm pulsed heating in the loop system. The comparison of observations and model provides constraints on the heat deposition: a good agreement requires loop twisting and pulses deposited close to the footpoints with a duration of 0.5 min in one loop, and deposited in the corona with a duration of 2.5 min in another loop of the same loop system.

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“…However, in that case, the oscillatory signal has a characteristic square shape, which has not been found in observations. Recently, rapidly decaying acoustic oscillations induced by an impulsive energy release were found in the infinite field modelling [23] that reduces slow magnetoacoustic waves to the pure acoustic. Furthermore, some additional physical processes, for example the misbalance of the radiative losses, thermal conduction and unspecified background heating of the coronal plasma could either significantly increase or decrease the damping time [45].…”

Section: Decaying Harmonic Qppmentioning

confidence: 99%

“…[21,22]). Also, variation of the plasma temperature, for example, because of the radiative or thermal conductive cooling in the decaying phase of the flare, should increase the period of slow magnetoacoustic oscillations (e.g., [23]). In self-oscillations, e.g., the repetitive reconnection, the characteristic times could change, for example, because of the variation of the inflow rate, the anomalous resistivity connected with the local electric currents, etc.…”

Section: Introductionmentioning

confidence: 99%

Non-stationary quasi-periodic pulsations in solar and stellar flares

Nakariakov

Kolotkov

Kupriyanova

et al. 2018

Plasma Phys. Control. Fusion

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Often the enhanced electromagnetic radiation generated in solar and stellar flares shows a pronounced (quasi)-oscillatory pattern-quasi-periodic pulsations (QPP), with characteristic periods ranging from a fraction of a second to several tens of minutes. We review recent advances in the empirical study of QPP in solar and stellar flares, addressing the intrinsic nonstationarity of the signal, i.e. the variation of its amplitude, period or phase with time. This nonstationarity could form a basis for a classification of QPP, necessary for revealing specific physical mechanisms responsible for their appearance. We could identify two possible classes of QPP, decaying harmonic oscillations, and trains of symmetric triangular pulsations. Apparent similarities between QPP and irregular geomagnetic pulsations Pi offer a promising avenue for the knowledge transfer in both analytical techniques and theory. Attention is also paid to the effect of the flare trend on the detection and analysis of QPP.

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X-Ray Flare Oscillations Track Plasma Sloshing along Star-disk Magnetic Tubes in the Orion Star-forming Region

Cited by 31 publications

References 55 publications

A multi-wavelength view of magnetic flaring from PMS stars

A multi-wavelength view of magnetic flaring from PMS stars

Large-amplitude Quasiperiodic Pulsations as Evidence of Impulsive Heating in Hot Transient Loop Systems Detected in the EUV with SDO/AIA

Non-stationary quasi-periodic pulsations in solar and stellar flares

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