A Hot Ultraviolet Flare on the M Dwarf Star GJ 674

Froning, Cynthia S.; Kowalski, Adam F.; France, Kevin; Loyd, R. O. Parke; Schneider, P. C.; Youngblood, Allison; Wilson, D. J.; Brown, Alexander; Berta-Thompson, Zachory K.; Pineda, J. Sebastian; Linsky, J. L.; Rugheimer, Sarah; Miguel, Yamila

doi:10.3847/2041-8213/aaffcd

Cited by 57 publications

(66 citation statements)

References 38 publications

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“…IRIS provides robust continuum measurements of flares in the FUV as well (Tian et al, 2015). Multifarious types of FUV spectral shapes (in units of Å −1 ) have been reported in stellar flares: slightly rising toward shorter wavelengths (Froning et al, 2019), nearly flat continua (Hawley and Pettersen, 1991) and continua falling toward shorter wavelengths (Loyd et al, 2018b). However, in all cases the spectra are bluer than an extrapolation of the NUV optically thin Balmer-continuum recombination models, as inferred in IRIS data of solar flares (Heinzel and Kleint, 2014;Kowalski et al, 2017; see also Section 5.1.2).…”

Section: Figure 30mentioning

confidence: 99%

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

et al. 2021

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The Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images and spectra of the solar atmosphere since July 2013. IRIS is the highest resolution observatory to provide seamless coverage of spectra and images from the photosphere into the low corona. The unique combination of near- and far-ultraviolet spectra and images at sub-arcsecond resolution and high cadence allows the tracing of mass and energy through the critical interface between the surface and the corona or solar wind. IRIS has enabled research into the fundamental physical processes thought to play a role in the low solar atmosphere such as ion–neutral interactions, magnetic reconnection, the generation, propagation, and dissipation of waves, the acceleration of non-thermal particles, and various small-scale instabilities. IRIS has provided insights into a wide range of phenomena including the discovery of non-thermal particles in coronal nano-flares, the formation and impact of spicules and other jets, resonant absorption and dissipation of Alfvénic waves, energy release and jet-like dynamics associated with braiding of magnetic-field lines, the role of turbulence and the tearing-mode instability in reconnection, the contribution of waves, turbulence, and non-thermal particles in the energy deposition during flares and smaller-scale events such as UV bursts, and the role of flux ropes and various other mechanisms in triggering and driving CMEs. IRIS observations have also been used to elucidate the physical mechanisms driving the solar irradiance that impacts Earth’s upper atmosphere, and the connections between solar and stellar physics. Advances in numerical modeling, inversion codes, and machine-learning techniques have played a key role. With the advent of exciting new instrumentation both on the ground, e.g. the Daniel K. Inouye Solar Telescope (DKIST) and the Atacama Large Millimeter/submillimeter Array (ALMA), and space-based, e.g. the Parker Solar Probe and the Solar Orbiter, we aim to review new insights based on IRIS observations or related modeling, and highlight some of the outstanding challenges.

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Section: Figure 30mentioning

confidence: 99%

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

et al. 2021

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“…GJ 699 was observed between 2019 March and June with the Hubble Space Telescope (HST) and the Chandra X-ray Observatory as part of the Mega-MUSCLES 19 observing program (see Froning et al 2019). The observations (Table 1) were designed to record the highest fidelity UV and X-ray observations of GJ 699 obtained to date and extend existing panchromatic surveys of M dwarfs (France et al 2016).…”

Section: Hst and Chandra Observationsmentioning

confidence: 99%

“…The high-sensitivity COS G130M mode (Green et al 2012) allows us to track temporal variability in 10 4-7 K chromospheric, transition region, and coronal activity indicators (using the C II, Si III, C III, N V, Fe XIX, and Fe XXI emission lines) over an 8 hr interval (five contiguous spacecraft orbits). This observing method has been used to study the flare properties of a range of nearby M dwarfs (Loyd et al 2018a;Froning et al 2019).…”

Section: Hst and Chandra Observationsmentioning

confidence: 99%

The High-energy Radiation Environment around a 10 Gyr M Dwarf: Habitable at Last?

Duvvuri

Egan

Koskinen

et al. 2020

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Recent work has demonstrated that high levels of X-ray and UV activity on young M dwarfs may drive rapid atmospheric escape on temperate, terrestrial planets orbiting within the habitable zone. However, secondary atmospheres on planets orbiting older, less active M dwarfs may be stable and present more promising candidates for biomarker searches. In order to evaluate the potential habitability of Earth-like planets around old, inactive M dwarfs, we present new Hubble Space Telescope and Chandra X-ray Observatory observations of Barnard's Star (GJ 699), a 10 Gyr old M3.5 dwarf, acquired as part of the Mega-MUSCLES program. Despite the old age and long rotation period of Barnard's Star, we observe two FUV (δ 130 ≈5000 s; E 130 ≈10 29.5 erg each) and one X-ray (E X ≈10 29.2 erg) flares, and we estimate a high-energy flare duty cycle (defined here as the fraction of the time the star is in a flare state) of ∼25%. A publicly available 5 Å to 10μm spectral energy distribution of GJ 699 is created and used to evaluate the atmospheric stability of a hypothetical, unmagnetized terrestrial planet in the habitable zone (r HZ ∼0.1 au). Both thermal and nonthermal escape modeling indicate (1) the quiescent stellar XUV flux does not lead to strong atmospheric escape: atmospheric heating rates are comparable to periods of high solar activity on modern Earth, and (2) the flare environment could drive the atmosphere into a hydrodynamic loss regime at the observed flare duty cycle: sustained exposure to the flare environment of GJ 699 results in the loss of ≈87 Earth atmospheres Gyr −1 through thermal processes and ≈3 Earth atmospheres Gyr −1 through ion loss processes. These results suggest that if rocky planet atmospheres can survive the initial ∼5 Gyr of high stellar activity, or if a second-generation atmosphere can be formed or acquired, the flare duty cycle may be the controlling stellar parameter for the stability of Earth-like atmospheres around old M stars. Unified AstronomyThesaurus concepts: Solar extreme ultraviolet emission (1493); Exoplanet atmospheres (487); Stellar activity (1580); Stellar flares (1603); Habitable zone (696); Hubble Space Telescope (761)

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“…If the flux distribution in the flare corresponds to a blackbody with temperature higher than about 10,000 K, the true energies will be larger. Thus, Schmitt et al (2019) adopt a blackbody flux distribution corresponding to 12,000 K, while Froning et al (2019) and Howard et al (2020) use 40,000 K. From Table 3 the range in flare energy is 10 33.5 to 10 36 erg with a mean of 10 34.5 erg, but these may be just lower limits.…”

Section: Tess Early-type Flare Starsmentioning

confidence: 99%

Spots and Flares in Hot Main Sequence Stars Observed by Kepler, K2, and TESS

Balona

2021

Front. Astron. Space Sci.

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About 22,000 Kepler stars, 7,000 K2 stars, and nearly 60,000 TESS stars from sectors 1–24 have been classified according to variability type. A large proportion of stars of all spectral types appear to have periods in their light curves consistent with the expected rotation periods. A previous analysis of A- and late B-type stars suggests that these stars are indeed rotational variables. In this paper we have accumulated data to show that rotational modulation is present in about 30–40% of A- and B-type stars. A search for flares in TESS A- and B-type stars resulted in the detection of 102 flares in 57 stars. Analysis of flare energies show that the source of the flares cannot be a cool dwarf companion nor a F/G giant. The realization that a considerable fraction of A- and B-type stars are active indicates that a revision of current concepts regarding hot star envelopes is required.

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A Hot Ultraviolet Flare on the M Dwarf Star GJ 674

Cited by 57 publications

References 38 publications

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

The High-energy Radiation Environment around a 10 Gyr M Dwarf: Habitable at Last?

Spots and Flares in Hot Main Sequence Stars Observed by Kepler, K2, and TESS

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