Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects
The high-energy X-ray and ultraviolet (UV) radiation fields of exoplanet host stars play a crucial role in controlling the atmospheric conditions and the potential habitability of exoplanets. Major surveys of the X-ray/UV emissions from late-type (K and M spectral types) exoplanet hosts have been co...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astronomical Journal |
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| Online Access: | https://doi.org/10.3847/1538-3881/acc38a |
| _version_ | 1797697268886798336 |
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| author | Alexander Brown P. Christian Schneider Kevin France Cynthia S. Froning Allison A. Youngblood David J. Wilson R. O. Parke Loyd J. Sebastian Pineda Girish M. Duvvuri Adam F. Kowalski Zachory K. Berta-Thompson |
| author_facet | Alexander Brown P. Christian Schneider Kevin France Cynthia S. Froning Allison A. Youngblood David J. Wilson R. O. Parke Loyd J. Sebastian Pineda Girish M. Duvvuri Adam F. Kowalski Zachory K. Berta-Thompson |
| author_sort | Alexander Brown |
| collection | DOAJ |
| description | The high-energy X-ray and ultraviolet (UV) radiation fields of exoplanet host stars play a crucial role in controlling the atmospheric conditions and the potential habitability of exoplanets. Major surveys of the X-ray/UV emissions from late-type (K and M spectral types) exoplanet hosts have been conducted by the Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary systems (MUSCLES) and Mega-MUSCLES Hubble Space Telescope Treasury programs. These samples primarily consist of relatively old, “inactive,” low-mass stars. In this paper we present results from X-ray observations of the coronal emission from these stars obtained using the Chandra X-ray Observatory, the XMM-Newton Observatory, and the Neil Gehrels Swift Observatory. The stars effectively sample the coronal activity of low-mass stars over a wide range of masses and ages. The vast majority (21 of 23) of the stars are detected and their X-ray luminosities measured. Short-term flaring variability is detected for most of the fully convective ( M ≤ 0.35 M _⊙ ) stars but not for the more massive M dwarfs during these observations. Despite this difference, the mean X-ray luminosities for these two sets of M dwarfs are similar, with more massive (0.35 M _⊙ ≤ M ≤ 0.6 M _⊙ ) M dwarfs at ∼5 × 10 ^26 erg s ^−1 compared to ∼2 × 10 ^26 erg s ^−1 for fully convective stars older than 1 Gyr. Younger, fully convective M dwarfs have X-ray luminosities between 3 and 6 × 10 ^27 erg s ^−1 . The coronal X-ray spectra have been characterized and provide important information that is vital for the modeling of the stellar EUV spectra. |
| first_indexed | 2024-03-12T03:37:55Z |
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| institution | Directory Open Access Journal |
| issn | 1538-3881 |
| language | English |
| last_indexed | 2024-03-12T03:37:55Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astronomical Journal |
| spelling | doaj.art-9a337df8c10b4425afae47ed45e5c1842023-09-03T13:07:52ZengIOP PublishingThe Astronomical Journal1538-38812023-01-01165519510.3847/1538-3881/acc38aCoronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey ProjectsAlexander Brown0https://orcid.org/0000-0003-2631-3905P. Christian Schneider1https://orcid.org/0000-0002-5094-2245Kevin France2https://orcid.org/0000-0002-1002-3674Cynthia S. Froning3https://orcid.org/0000-0001-8499-2892Allison A. Youngblood4https://orcid.org/0000-0002-1176-3391David J. Wilson5https://orcid.org/0000-0001-9667-9449R. O. Parke Loyd6https://orcid.org/0000-0001-5646-6668J. Sebastian Pineda7https://orcid.org/0000-0002-4489-0135Girish M. Duvvuri8https://orcid.org/0000-0002-7119-2543Adam F. Kowalski9https://orcid.org/0000-0001-7458-1176Zachory K. Berta-Thompson10https://orcid.org/0000-0002-3321-4924Center for Astrophysics and Space Astronomy, University of Colorado , 389 UCB, Boulder, CO 80309, USA ; Alexander.Brown@colorado.eduHamburger Sternwarte, Gojenbergsweg 112, D-21039, Hamburg, GermanyLaboratory for Atmospheric and Space Physics, University of Colorado , 600 UCB, Boulder, CO 80309, USAMcDonald Observatory, University of Texas at Austin , Austin, TX 78712, USA; Southwest Research Institute , 6220 Culebra Rd., San Antonio, TX 78238, USAExoplanets and Stellar Astrophysics Lab, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USALaboratory for Atmospheric and Space Physics, University of Colorado , 600 UCB, Boulder, CO 80309, USASchool of Earth and Space Exploration, Arizona State University , Tempe, AZ 85287, USALaboratory for Atmospheric and Space Physics, University of Colorado , 600 UCB, Boulder, CO 80309, USACenter for Astrophysics and Space Astronomy, University of Colorado , 389 UCB, Boulder, CO 80309, USA ; Alexander.Brown@colorado.edu; Laboratory for Atmospheric and Space Physics, University of Colorado , 600 UCB, Boulder, CO 80309, USA; Department of Astrophysical and Planetary Sciences, University of Colorado , Boulder, CO 80309, USALaboratory for Atmospheric and Space Physics, University of Colorado , 600 UCB, Boulder, CO 80309, USA; Department of Astrophysical and Planetary Sciences, University of Colorado , Boulder, CO 80309, USA; National Solar Observatory, University of Colorado , 3665 Discovery Drive, Boulder, CO 80303, USACenter for Astrophysics and Space Astronomy, University of Colorado , 389 UCB, Boulder, CO 80309, USA ; Alexander.Brown@colorado.edu; Department of Astrophysical and Planetary Sciences, University of Colorado , Boulder, CO 80309, USAThe high-energy X-ray and ultraviolet (UV) radiation fields of exoplanet host stars play a crucial role in controlling the atmospheric conditions and the potential habitability of exoplanets. Major surveys of the X-ray/UV emissions from late-type (K and M spectral types) exoplanet hosts have been conducted by the Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary systems (MUSCLES) and Mega-MUSCLES Hubble Space Telescope Treasury programs. These samples primarily consist of relatively old, “inactive,” low-mass stars. In this paper we present results from X-ray observations of the coronal emission from these stars obtained using the Chandra X-ray Observatory, the XMM-Newton Observatory, and the Neil Gehrels Swift Observatory. The stars effectively sample the coronal activity of low-mass stars over a wide range of masses and ages. The vast majority (21 of 23) of the stars are detected and their X-ray luminosities measured. Short-term flaring variability is detected for most of the fully convective ( M ≤ 0.35 M _⊙ ) stars but not for the more massive M dwarfs during these observations. Despite this difference, the mean X-ray luminosities for these two sets of M dwarfs are similar, with more massive (0.35 M _⊙ ≤ M ≤ 0.6 M _⊙ ) M dwarfs at ∼5 × 10 ^26 erg s ^−1 compared to ∼2 × 10 ^26 erg s ^−1 for fully convective stars older than 1 Gyr. Younger, fully convective M dwarfs have X-ray luminosities between 3 and 6 × 10 ^27 erg s ^−1 . The coronal X-ray spectra have been characterized and provide important information that is vital for the modeling of the stellar EUV spectra.https://doi.org/10.3847/1538-3881/acc38aM dwarf starsK dwarf starsStellar x-ray flaresPlanet hosting stars |
| spellingShingle | Alexander Brown P. Christian Schneider Kevin France Cynthia S. Froning Allison A. Youngblood David J. Wilson R. O. Parke Loyd J. Sebastian Pineda Girish M. Duvvuri Adam F. Kowalski Zachory K. Berta-Thompson Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects The Astronomical Journal M dwarf stars K dwarf stars Stellar x-ray flares Planet hosting stars |
| title | Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects |
| title_full | Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects |
| title_fullStr | Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects |
| title_full_unstemmed | Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects |
| title_short | Coronal X-Ray Emission from Nearby, Low-mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects |
| title_sort | coronal x ray emission from nearby low mass exoplanet host stars observed by the muscles and mega muscles hst treasury survey projects |
| topic | M dwarf stars K dwarf stars Stellar x-ray flares Planet hosting stars |
| url | https://doi.org/10.3847/1538-3881/acc38a |
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