A Hot Ultraviolet Flare on the M Dwarf Star GJ 674
Cynthia S. FroningA. KowalskiK. FranceR. O. Parke LoydP. C. SchneiderAllison YoungbloodD. WilsonA. G. A. BrownZachory K. Berta-ThompsonJ. Sebastian PinedaJeffrey L. LinskySarah RugheimerYamila Miguel
1
Citation
2
Reference
10
Related Paper
Citation Trend
Abstract:
As part of the Mega MUSCLES Hubble Space Telescope (HST) Treasury program, we obtained time-series ultraviolet spectroscopy of the M2.5V star, GJ~674. During the FUV monitoring observations, the target exhibited several small flares and one large flare (E_FUV = 10^{30.75} ergs) that persisted over the entirety of a HST orbit and had an equivalent duration >30,000 sec, comparable to the highest relative amplitude event previously recorded in the FUV. The flare spectrum exhibited enhanced line emission from chromospheric, transition region, and coronal transitions and a blue FUV continuum with an unprecedented color temperature of T_c ~ 40,000+/-10,000 K. In this paper, we compare the flare FUV continuum emission with parameterizations of radiative hydrodynamic model atmospheres of M star flares. We find that the observed flare continuum can be reproduced using flare models but only with the ad hoc addition of hot, dense emitting component. This observation demonstrates that flares with hot FUV continuum temperatures and significant EUV/FUV energy deposition will continue to be of importance to exoplanet atmospheric chemistry and heating even as the host M dwarfs age beyond their most active evolutionary phases.Keywords:
Flare
Flare star
Ultraviolet
Flare
Flare star
Variation (astronomy)
Star (game theory)
Cite
Citations (5)
Coordinated X ray, optical, and radio observations of the flare star YZ CMi are reported. Twenty-two minor optical flares and twelve radio events were recorded. No major optical flares, greater than 3 magnitudes, were observed. Although no flare-related X ray emission was observed, the measured upper limits in this band enable meaningful comparisons with published flare star models. Three of the five models predicting the relative X ray-to-optical or radio flare luminosities are in serious disagreement with the observations. For the largest optical flare with coincident X ray coverage, the 3 sigma upper limit on X ray emission in the 0.15 to 0.8 keV band is 8.7 x 10/sup 28/ erg/s, corresponding to a ratio of X ray to B-band luminosity of less than 0.3. Based on the present results, the contribution of the flares of UV Ceti flare stars to the galactic component of the diffuse soft X ray background is less than 0.2 percent.
Flare
Flare star
Cite
Citations (0)
Flare
Flare star
Chromosphere
Cite
Citations (3)
The results from a flare star investigation in the open cluster Alpha Persei are presented. Photographic flare star monitoring and CCD photometry of the discovered 4 new flare stars are made. The flare star activity phenomenon is restricted to the classical flare stars (UV Ceti type) as classified in the GCVS. The V/V-I diagramme of the members of the cluster with the locations of the considered flare stars is given. Most of the flare stars are probable cluster members. The flare frequency determined from the Rozhen flare star monitoring is very low–one flare event occurs for 38.5 hours effective observing time. Comparison with the flare activity of the Pleiades is made because of the small difference in the age and distance of the clusters.
Flare
Flare star
Pleiades
H-alpha
Cite
Citations (1)
Flare
Flare star
Pleiades
Solar flare
Cite
Citations (3)
Stellar flare is one of the most challenging problems in Astrophysics. Up to now, most of the detected flare stars are of the late spectral type (e.g. UV Ceti type stars etc.). The non-classical flare stars with early spectral type are very rare, In 1975, Kunkel collected a few possible early type flare stars in his review paper, all of which had emission line spectra (W.E.Kunkal, 1975). They are many orders of magnitude more powerful than dMe flares. The nature of this kind of flare stars are unknown.Recently, a later A-type flare star BD+47 819, near the open cluster a Persei, was discovered by Jun-jie Wang. The V magnitude of the star was 9.25, ans B-V = 0.413(Prosser, 1992). Its spectral type was A7 in CSI catalog of Strasbourg (1979), and A5 in Fehrenbach’s list(Fehrenbach, 1987).BD+47 819 will be taken a special interest to be recgnized, not only for lack of knowledge on the nature of all the early type flare stars, but also as it is a peculiar A-5 type variable with flare activity. From its spect
Flare
Flare star
Variable star
Cite
Citations (0)
Preliminary results of a photometric search for non-flare activity of the flare star EV Lac during June-August 1994 are presented. These observations are part of the long-term project entitled “Investigation of pre-flare processes on flare stars” being carried out at the Observatory of the Jordan Valley Regional College since July 1994. The project was motivated by reports of the existence of slow, low-amplitude non-periodic variability of both spectral lines and continuum outside/between flares (Rodono et al. 1979, Roizman et al. 1984).
Flare
Flare star
Solar flare
Cite
Citations (0)
Four-colour high-speed photometric observations of the UV Ceti type flare star Wolf 424AB are presented. This system may be one of the most active flare stars known. During a period of 2.62 hr 12 flares were detected and flare activity accounted for approximately 8 per cent of the total energy received from the system in the U-bandpass. The observations of the largest flare are compared with the predictions of the fast-electron flare model proposed by Gurzadyan which is remarkably successful though some discrepancies exist. The basic hypothesis of the fast-electron model is questioned.
Flare
Flare star
Solar flare
Cite
Citations (18)
Simultaneous optical and radio observations of the flare star EV Lac have been carried out. The only optical flare detected was followed by a burst of radio emission which lagged about 4 minutes behind the optical event. Key words: flare stars
Flare
Flare star
Solar flare
Cite
Citations (3)
The results from a flare star investigation in the open cluster Alpha Persei are presented. Photographic flare star monitoring and CCD photometry of the discovered 4 new flare stars are made. The flare star activity phenomenon is restricted to the classical flare stars (UV Ceti type) as classified in the GCVS. The V/V-I diagramme of the members of the cluster with the locations of the considered flare stars is given. Most of the flare stars are probable cluster members. The flare frequency determined from the Rozhen flare star monitoring is very low–one flare event occurs for 38.5 hours effective observing time. Comparison with the flare activity of the Pleiades is made because of the small difference in the age and distance of the clusters.
Flare
Flare star
Pleiades
Cite
Citations (0)