Estimating the ultraviolet emission of M dwarfs with exoplanets from Ca II and Hα

• Autores: Melbourne, Katherine; Youngblood, Allison; France, Kevin; Froning, Cynthia S.; Pineda, J. Sebastian; Shkolnik, Evgenya L.; Wilson, David J.; Wood, Brian E.; Basu, Sarbani; Roberge, Aki; Schlieder, Joshua E.; Cauley, P. Wilson; Loyd, R. O. Parke; Newton, Elisabeth R.; Schneider, Adam; Arulanantham, Nicole; Berta Thompson, Zachory; Brown, Alexander; Buccino, Andrea Paola; Kempton, Eliza; Linsky, Jeffrey L.; Logsdon, Sarah E.; Mauas, Pablo Jacobo David; Pagano, Isabella; Peacock, Sarah; Redfield, Seth; Rugheimer, Sarah; Schneider, P. Christian; Teal, D. J.; Tian, Feng; Tilipman, Dennis; Vieytes, Mariela Cristina
• Año de publicación: 2020
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Stellar chromospheres; M Dwarfs; Exoplanets
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

M dwarf stars are excellent candidates around which to search for exoplanets, including temperate, Earth-sized planets. To evaluate the photochemistry of the planetary atmosphere, it is essential to characterize the UV spectral energy distribution of the planet's host star. This wavelength regime is important because molecules in the planetary atmosphere such as oxygen and ozone have highly wavelength-dependent absorption cross sections that peak in the UV (900-3200 Å). We seek to provide a broadly applicable method of estimating the UV emission of an M dwarf, without direct UV data, by identifying a relationship between noncontemporaneous optical and UV observations. Our work uses the largest sample of M dwarf star far- and near-UV observations yet assembled. We evaluate three commonly observed optical chromospheric activity indices-Hα equivalent widths and log10 LHα/Lbol, and the Mount Wilson Ca II H&K S and RHK indices-using optical spectra from the HARPS, UVES, and HIRES archives and new HIRES spectra. Archival and new Hubble Space Telescope COS and STIS spectra are used to measure line fluxes for the brightest chromospheric and transition region emission lines between 1200 and 2800 Å. Our results show a correlation between UV emission-line luminosity normalized to the stellar bolometric luminosity and Ca II RHK with standard deviations of 0.31-0.61 dex (factors of ∼2-4) about the best-fit lines. We also find correlations between normalized UV line luminosity and Hα log10 LHα/Lbol and the S index. These relationships allow one to estimate the average UV emission from M0 to M9 dwarfs when UV data are not available.
Fil: Melbourne, Katherine. University of Yale; Estados Unidos. Ball Aerospace & Technologies Corp; Estados Unidos
Fil: Youngblood, Allison. State University of Colorado at Boulder; Estados Unidos. National Aeronautics and Space Administration; Estados Unidos
Fil: France, Kevin. State University of Colorado at Boulder; Estados Unidos
Fil: Froning, Cynthia S.. University of Texas at Austin; Estados Unidos
Fil: Pineda, J. Sebastian. State University of Colorado at Boulder; Estados Unidos
Fil: Shkolnik, Evgenya L.. Arizona State University; Estados Unidos
Fil: Wilson, David J.. University of Texas at Austin; Estados Unidos
Fil: Wood, Brian E.. Naval Research Laboratory. Space Science Division; Estados Unidos
Fil: Basu, Sarbani. University of Yale; Estados Unidos
Fil: Roberge, Aki. National Aeronautics and Space Administration; Estados Unidos
Fil: Schlieder, Joshua E.. National Aeronautics and Space Administration; Estados Unidos
Fil: Cauley, P. Wilson. State University of Colorado at Boulder; Estados Unidos
Fil: Loyd, R. O. Parke. Arizona State University; Estados Unidos
Fil: Newton, Elisabeth R.. Dartmouth College; Estados Unidos
Fil: Schneider, Adam. Arizona State University; Estados Unidos
Fil: Arulanantham, Nicole. State University of Colorado at Boulder; Estados Unidos
Fil: Berta Thompson, Zachory. State University of Colorado at Boulder; Estados Unidos
Fil: Brown, Alexander. State University of Colorado at Boulder; Estados Unidos
Fil: Buccino, Andrea Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Fil: Kempton, Eliza. University of Maryland; Estados Unidos
Fil: Linsky, Jeffrey L.. State University of Colorado at Boulder; Estados Unidos
Fil: Logsdon, Sarah E.. National Aeronautics and Space Administration; Estados Unidos
Fil: Mauas, Pablo Jacobo David. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Fil: Pagano, Isabella. Istituto Nazionale di Astrofisica; Italia
Fil: Peacock, Sarah. University of Arizona; Estados Unidos
Fil: Redfield, Seth. Ohio Wesleyan University.; Estados Unidos
Fil: Rugheimer, Sarah. University of Oxford; Reino Unido
Fil: Schneider, P. Christian. Hamburger Sternwarte; Alemania
Fil: Teal, D. J.. University of Maryland; Estados Unidos. National Aeronautics and Space Administration; Estados Unidos
Fil: Tian, Feng. Macau University of Science and Technology; China
Fil: Tilipman, Dennis. State University of Colorado at Boulder; Estados Unidos
Fil: Vieytes, Mariela Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Universidad Nacional de Tres de Febrero; Argentina