A compact flare eclipsed in the corona of SV Camelopardalis

Sanz-Forcada, J.; Favata, F.; Micela, G.

doi:10.1051/0004-6361:20053666

Cited by 7 publications

(6 citation statements)

References 34 publications

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“…[2,3,4] Support for this interpretation comes from other wavelength regions as well. Similar results have been obtained for other short-period eclipsing active binary systems [6,7], bolstering support for the importance of the polar regions in the coronae of rapidly rotating active binary systems. Similar results have been obtained for other short-period eclipsing active binary systems [6,7], bolstering support for the importance of the polar regions in the coronae of rapidly rotating active binary systems.…”

Section: Introductionsupporting

confidence: 84%

Polar Exploration and Coronal Structure in the Active Binary HR 5110

Huenemoerder¹,

Osten²,

Kesich³

et al. 2009

AIP Conference Proceedings

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Overwhelming evidence exists for the importance of polar regions in controlling stellar atmospheric structure and dynamics in active binary systems. Uncertainties about the geometry of coronal emission have made conclusions about coronal structures on such stars ambiguous. We have obtained Chandra, VLA and VLBA observations of the nearly pole-on active binary system HR 5110 in order to investigate coronal structures without such ambiguity. The X-ray spectra will constrain thermal coronal volumes through determinaion of electron densities; radio observations will constrain non-thermal coronal volumes directly, and allow an estimation of the relative importance of thermal and nonthermal plasma in controlling and structuring active stellar coronae. Here we present preliminary results from the Chandra observations.

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Section: Introductionsupporting

confidence: 84%

Polar Exploration and Coronal Structure in the Active Binary HR 5110

Huenemoerder¹,

Osten²,

Kesich³

et al. 2009

AIP Conference Proceedings

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“…In this paper, we have considered an alternative geometric interpretation in which these atypical flare morphologies are produced by the eclipsing of flaring plasma due to the rotation of the host star. This interpretation has been considered for individual flares in previous studies (Skinner et al 1997; Schmitt & Favata 1999; Stelzer et al 1999; Schmitt et al 2003; Sanz‐Forcada et al 2006, 2007).…”

Section: Discussionmentioning

confidence: 91%

“…Based on solar analogies, such flares are often interpreted as being the result of multiple heating events in the same flaring loop or the superposition of separate overlapping flares (for example, see Reale et al 2004 of the host star. This interpretation has been considered for individual flares in previous studies (Skinner et al 1997, Stelzer et al 1999, Schmitt & Favata 1999, Schmitt et al 2003, Sanz-Forcada et al 2006, Sanz-Forcada et al 2007.…”

Section: Discussionmentioning

confidence: 92%

“…In this alternative, atypical flare morphologies are not the result of multiple flare events, but are the result of the time‐variable eclipsing of the flaring coronal plasma caused by the rotation of the host star. Previous studies have used this interpretation to explain the morphologies of stellar flares using eclipsing by the flares’ host stars (Skinner et al 1997; Stelzer et al 1999) or by a companion star in eclipsing binary systems (Schmitt & Favata 1999; Schmitt, Ness & Franco 2003; Sanz‐Forcada, Favata & Micela 2006, 2007). In this work, we explore the eclipsing interpretation within the framework of a single loop model.…”

Section: Introductionmentioning

confidence: 99%

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The soft X-ray light curves of partially eclipsed stellar flares

Johnstone¹,

Gregory²,

Jardine³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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Most stellar flares' soft X-ray light curves possess a 'typical' morphology, which consists of a rapid rise followed by a slow exponential decay. However, a study of 216 of the brightest flares on 161 pre-main-sequence stars, observed during the Chandra Orion Ultradeep Project (COUP), showed that many flare light curves depart from this typical morphology. While this can be attributed to the superposition of multiple typical flares, we explore the possibility that the time-variable eclipsing of flares by their host stars may also be an important factor. We assume each flare is contained within a single, uniform plasma density magnetic loop and specify the intrinsic variation of the flare's emission measure with time. We consider rotational eclipse not only by the star itself, but also by circumstellar discs and flare-associated prominences. Based on this simple model, we generate a set of flares similar to those observed in the COUP data base. Many eclipses simply reduce the flare's maximum emission measure or decay time. We conclude therefore that eclipses often pass undetected, but usually have only a modest influence on the flare emission measure profile and hence the derived loop lengths. We show that eclipsing can easily reproduce the observed atypical flare morphologies. The number of atypical modelled flare morphologies is, however, much less than that found in the COUP sample. The large number of observed atypical flare morphologies, therefore, must be attributed to other processes such as multiple flaring loops.

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“…This is one of our target-star sample. Sanz-Forcada et al (2006) have presented the XMM measurements from 2001 (DETID=75409) and 2003 (DETID=75410), and reported an eclipsed X-ray flare during the 2001 observation. They discuss only the X-ray data.…”

Section: The Eclipsing Rs Cvn-type Binary Sv Cammentioning

confidence: 99%

A survey of stellar X-ray flares from theXMM-Newtonserendipitous source catalogue: HIPPARCOS-Tycho cool stars

Pye

Rosen

Fyfe

et al. 2015

A&A

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Context. The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is indicative of very energetic, transient phenomena, associated with energy release via magnetic reconnection. Aims. We present a uniform, large-scale survey of X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its associated data products provide an excellent basis for a comprehensive and sensitive survey of stellar flares -both from targeted active stars and from those observed serendipitously in the half-degree diameter field-of-view of each observation. Methods. The 2XMM Catalogue and the associated time-series ("light-curve") data products have been used as the basis for a survey of X-ray flares from cool stars in the Hipparcos-Tycho-2 catalogue. In addition, we have generated and analysed spectrally-resolved (i.e. hardness-ratio), X-ray light-curves. Where available, we have compared XMM OM UV/optical data with the X-ray light-curves. Results. Our sample contains ∼130 flares with well-observed profiles; they originate from ∼70 stars. The flares range in duration from ∼10 3 to ∼10 4 s, have peak X-ray fluxes from ∼10 −13 to ∼10 −11 erg cm −2 s −1 , peak X-ray luminosities from ∼10 29 to ∼10 32 erg s −1 , and X-ray energy output from ∼10 32 to ∼10 35 erg. Most of the ∼30 serendipitously-observed stars have little previously reported information. The hardness-ratio plots clearly illustrate the spectral (and hence inferred temperature) variations characteristic of many flares, and provide an easily accessible overview of the data. We present flare frequency distributions from both target and serendipitous observations. The latter provide an unbiased (with respect to stellar activity) study of flare energetics; in addition, they allow us to predict numbers of stellar flares that may be detected in future X-ray wide-field surveys. The serendipitous sample demonstrates the need for care when calculating flaring rates, especially when normalising the number of flares to a total exposure time, where it is important to consider both the stars seen to flare and those from which variability was not detected (i.e. measured as non-variable), since in our survey, the latter outnumber the former by more than a factor ten. The serendipitous variable and "non-variable" stars appear very similar in terms of the distributions of general properties such as quiescent X-ray luminosity; from the available data, it is unclear whether the distinction by flaring is due to an additional, intrinsic property such as intra-system interactions in a close binary system, or is simply the result of limited observations and detection thresholds on a random flaring process, with no real difference between the two samples, or may be a combination of these effects. However, the number of detected flares compared with the number of stars not seen to vary is broadly consistent with estimates based on Poisson statistics.

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A compact flare eclipsed in the corona of SV Camelopardalis

Cited by 7 publications

References 34 publications

Polar Exploration and Coronal Structure in the Active Binary HR 5110

Polar Exploration and Coronal Structure in the Active Binary HR 5110

The soft X-ray light curves of partially eclipsed stellar flares

A survey of stellar X-ray flares from theXMM-Newtonserendipitous source catalogue: HIPPARCOS-Tycho cool stars

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