A Cool Star Flare Reveals an Unexpectedly Hot Emission Component
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==Introduction== | ==Introduction== | ||
- | The [http://cos.colorado.edu/~kevinf/muscles.html MUSCLES and Mega-MUSCLES Treasury Surveys] are large observing programs that are using the Hubble Space Telescope, Chandra X-ray Observatory, XMM-Newton, the Neil Gehrels Swift Observatory, and a suite of ground-based optical telescopes to construct panchromatic (5 Å - 5.5 μm) spectral energy distributions for a representative sample of M dwarf stars (Refs [0],[1]). The goal of the surveys is to establish | + | The [http://cos.colorado.edu/~kevinf/muscles.html MUSCLES and Mega-MUSCLES Treasury Surveys] are large observing programs that are using the Hubble Space Telescope, Chandra X-ray Observatory, XMM-Newton, the Neil Gehrels Swift Observatory, and a suite of ground-based optical telescopes to construct panchromatic (5 Å - 5.5 μm) spectral energy distributions for a representative sample of M dwarf stars (Refs [0],[1]). The primary goal of the surveys is to establish characterize the stellar energetic radiation environment and activity levels in dwarf stars and their effects on exoplanet atmospheres and habitability; however, the survey observations have also been excellent probes of the energetic properties of flares in dwarf stars, providing X-ray and ultraviolet (UV) time-resolved spectroscopy of targets. |
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+ | One of the targets in the Mega-MUSCLES survey was the M2.5V (0.35 M⊙) star GJ674. It hosts a [https://en.wikipedia.org/wiki/Hot_Neptune hot Neptune] exoplanet in a 4.7 day orbit. GJ674 is classified as a "weakly active" star: it has regular starspot activity and shows emission lines of CaII H&K, but does not show Hα in emission, the characteristic definition of an active flare star. | ||
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==Observations and Flare Properties== | ==Observations and Flare Properties== | ||
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+ | The survey programs are centered about far-ultraviolet spectroscopy and time-series monitoring of the stars using the [http://www.stsci.edu/hst/cos Cosmic Origins Spectrograph (COS)] and [http://www.stsci.edu/hst/instrumentation/stis Space Telescope Imaging Spectrograph] instruments on board the [https://hubblesite.org/ Hubble Space Telescope]. During the observations with COS (Ref. [2]), GJ 674 experienced a large flare (Figure 1). | ||
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+ | [[Image:gj674_cos_lightcurve.png|300px|thumb|right|'''Figure 1''': During FUV observations with the Hubble Space Telescope, the M2.5V dwarf star, GJ 674, exhibited several small flares and one large flare in the last orbit.]] | ||
==Hydrodynamic Models and | ==Hydrodynamic Models and |
Revision as of 20:38, 28 August 2019
A Cool Star Flare Reveals an Unexpectedly Hot Emission Component | |
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Number: | 112 |
1st Author: | C. S. Froning |
2nd Author: | A. Kowalski |
Published: | September 5, 2019 |
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Contents |
Introduction
The MUSCLES and Mega-MUSCLES Treasury Surveys are large observing programs that are using the Hubble Space Telescope, Chandra X-ray Observatory, XMM-Newton, the Neil Gehrels Swift Observatory, and a suite of ground-based optical telescopes to construct panchromatic (5 Å - 5.5 μm) spectral energy distributions for a representative sample of M dwarf stars (Refs [0],[1]). The primary goal of the surveys is to establish characterize the stellar energetic radiation environment and activity levels in dwarf stars and their effects on exoplanet atmospheres and habitability; however, the survey observations have also been excellent probes of the energetic properties of flares in dwarf stars, providing X-ray and ultraviolet (UV) time-resolved spectroscopy of targets.
One of the targets in the Mega-MUSCLES survey was the M2.5V (0.35 M⊙) star GJ674. It hosts a hot Neptune exoplanet in a 4.7 day orbit. GJ674 is classified as a "weakly active" star: it has regular starspot activity and shows emission lines of CaII H&K, but does not show Hα in emission, the characteristic definition of an active flare star.
Observations and Flare Properties
The survey programs are centered about far-ultraviolet spectroscopy and time-series monitoring of the stars using the Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph instruments on board the Hubble Space Telescope. During the observations with COS (Ref. [2]), GJ 674 experienced a large flare (Figure 1).
==Hydrodynamic Models and
Conclusion
References
[0] The MUSCLES Treasury Survey. I. Motivation and Overview [1] Flexing our MUSCLES: The HST Mega-MUSCLES Treasury Survey [2] The Cosmic Origins Spectrograph: on-orbit instrument performance [3] A Hot Ultraviolet Flare on the M Dwarf Star GJ 674
RHESSI Nugget Date | 5 September 2019 + |
RHESSI Nugget First Author | C. S. Froning + |
RHESSI Nugget Index | 112 + |
RHESSI Nugget Second Author | A. Kowalski + |