Skip to content

Research at St Andrews

The MUSCLES Treasury Survey. II. Intrinsic Lyα and extreme ultraviolet spectra of K and M dwarfs with exoplanets

Research output: Contribution to journalArticle

Author(s)

Allison Youngblood, Kevin France, R. O. Parke Loyd, Jeffrey L. Linsky, Seth Redfield, P. Christian Schneider, Brian E. Wood, Alexander Brown, Cynthia Froning, Yamila Miguel, Sarah Rugheimer, Lucianne Walkowicz

Abstract

The ultraviolet (UV) spectral energy distributions (SEDs) of low-mass (K- and M-type) stars play a critical role in the heating and chemistry of exoplanet atmospheres, but are not observationally well-constrained. Direct observations of the intrinsic flux of the Lyα line (the dominant source of UV photons from low-mass stars) are challenging, as interstellar H i absorbs the entire line core for even the closest stars. To address the existing gap in empirical constraints on the UV flux of K and M dwarfs, the MUSCLES Hubble Space Telescope Treasury Survey has obtained UV observations of 11 nearby M and K dwarfs hosting exoplanets. This paper presents the Lyα and extreme-UV spectral reconstructions for the MUSCLES targets. Most targets are optically inactive, but all exhibit significant UV activity. We use a Markov Chain Monte Carlo technique to correct the observed Lyα profiles for interstellar absorption, and we employ empirical relations to compute the extreme-UV SED from the intrinsic Lyα flux in ∼100 bins from 100-1170. The reconstructed Lyα profiles have 300 km s-1 broad cores, while >1% of the total intrinsic Lyα flux is measured in extended wings between 300 and 1200 km s-1. The Lyα surface flux positively correlates with the Mg ii surface flux and negatively correlates with the stellar rotation period. Stars with larger Lyα surface flux also tend to have larger surface flux in ions formed at higher temperatures, but these correlations remain statistically insignificant in our sample of 11 stars. We also present H i column density measurements for 10 new sightlines through the local interstellar medium.

Close

Details

Original languageEnglish
Article number101
Number of pages18
JournalAstrophysical Journal
Volume824
Issue number2
DOIs
Publication statusPublished - 20 Jun 2016

    Research areas

  • ISM: clouds, Stars: low-mass

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by journal

  1. A cancellation nanoflare model for solar chromospheric and coronal heating. II. 2D theory and simulations

    Syntelis, P., Priest, E. R. & Chitta, L. P., 7 Feb 2019, In : Astrophysical Journal. 872, 1, 15 p., 32.

    Research output: Contribution to journalArticle

  2. Heating effects from driven transverse and Alfvén waves in coronal loops

    Guo, M., Van Doorsselaere, T., Karampelas, K., Li, B., Antolin, P. & De Moortel, I., 10 Jan 2019, In : Astrophysical Journal. 870, 2, 10 p., 55.

    Research output: Contribution to journalArticle

  3. The Sloan Digital Sky Survey Reverberation Mapping Project: systematic investigations of short-timescale CIV broad absorption line variability

    Hemler, Z. S., Grier, C. J., Brandt, W. N., Hall, P. B., Horne, K., Shen, Y., Trump, J. R., Schneider, D. P., Vivek, M., Bizyaev, D., Oravetz, A., Oravetz, D. & Pan, K., 6 Feb 2019, In : Astrophysical Journal. 872, 1, 21.

    Research output: Contribution to journalArticle

  4. The rotation-disk connection in young brown dwarfs: strong evidence for early rotational braking

    Moore, K., Scholz, A. & Jayawardhana, R., 20 Feb 2019, In : Astrophysical Journal. 872, 2, 20 p., 159.

    Research output: Contribution to journalArticle

  5. A comparison of simulated JWST observations derived from equilibrium and non-equilibrium chemistry models of giant exoplanets

    Blumenthal, S. D., Mandell, A. M., Hébrard, E., Batalha, N. E., Cubillos, P. E., Rugheimer, S. & Wakeford, H. R., 30 Jan 2018, In : Astrophysical Journal. 853, 2, 138.

    Research output: Contribution to journalArticle

Related by journal

  1. Astrophysical Journal (Journal)

    Carolin Villforth (Reviewer)
    2011 → …

    Activity: Publication peer-review and editorial work typesPeer review of manuscripts

  2. Astrophysical Journal (Journal)

    Christiane Helling (Reviewer)
    1 Jan 200631 Dec 2017

    Activity: Publication peer-review and editorial work typesPeer review of manuscripts

  3. Astrophysical Journal (Journal)

    Duncan Hendry Mackay (Editor)
    1997 → …

    Activity: Publication peer-review and editorial work typesEditor of research journal

  4. Astrophysical Journal (Journal)

    Alan William Hood (Editor)
    1980 → …

    Activity: Publication peer-review and editorial work typesEditor of research journal

ID: 244634755