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Testing Lyα emission-line reconstruction routines at multiple velocities in one system
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Wilson, David J., Youngblood, Allison, Toloza, Odette, Drake, Jeremy J., France, Kevin, Froning, Cynthia S., Gaensicke, B. T., Redfield, Seth and Wood, Brian E. (2022) Testing Lyα emission-line reconstruction routines at multiple velocities in one system. The Astrophysical Journal, 936 (2). 189. doi:10.3847/1538-4357/ac87a8
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WRAP-Testing-Lyα-emission-line-reconstruction-routines-velocities-system-22.pdf - Published Version - Requires a PDF viewer. Available under License Creative Commons Attribution 4.0. Download (2712Kb) | Preview |
Official URL: http://dx.doi.org/10.3847/1538-4357/ac87a8
Abstract
The 1215.67 Å H i Lyα emission line dominates the ultraviolet flux of low-mass stars, including the majority of known exoplanet hosts. Unfortunately, strong attenuation by the interstellar medium (ISM) obscures the line core in most stars, requiring the intrinsic Lyα flux to be reconstructed based on fits to the line wings. We present a test of the widely used Lyα emission-line reconstruction code lyapy using phase-resolved, medium-resolution STIS G140M observations of the close white dwarf–M dwarf binary EG UMa. The Doppler shifts induced by the binary orbital motion move the Lyα emission line in and out of the region of strong ISM attenuation. Reconstructions of each spectrum should produce the same Lyα profile regardless of phase, under the well-justified assumption that there is no intrinsic line variability between observations. Instead, we find that the reconstructions underestimate the Lyα flux by almost a factor of 2 for the lowest velocity, most attenuated spectrum, due to a degeneracy between the intrinsic Lyα and ISM profiles. Our results imply that many stellar Lyα fluxes derived from G140M spectra reported in the literature may be underestimated, with potential consequences for, for example, estimates of extreme-ultraviolet stellar spectra and ultraviolet inputs into simulations of exoplanet atmospheres.
| Item Type: | Journal Article | ||||||||||||
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| Subjects: | Q Science > QB Astronomy | ||||||||||||
| Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||||||
| Library of Congress Subject Headings (LCSH): | Dwarf stars , White dwarf stars , Double stars, Ultraviolet astronomy , Stars with planets | ||||||||||||
| Journal or Publication Title: | The Astrophysical Journal | ||||||||||||
| Publisher: | Institute of Physics Publishing, Inc. | ||||||||||||
| ISSN: | 0004-637X | ||||||||||||
| Official Date: | 14 September 2022 | ||||||||||||
| Dates: |
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| Volume: | 936 | ||||||||||||
| Number: | 2 | ||||||||||||
| Article Number: | 189 | ||||||||||||
| DOI: | 10.3847/1538-4357/ac87a8 | ||||||||||||
| Status: | Peer Reviewed | ||||||||||||
| Publication Status: | Published | ||||||||||||
| Access rights to Published version: | Open Access | ||||||||||||
| Copyright Holders: | © 2022. The Author(s). Published by the American Astronomical Society. | ||||||||||||
| Date of first compliant deposit: | 21 October 2022 | ||||||||||||
| Date of first compliant Open Access: | 21 October 2022 | ||||||||||||
| RIOXX Funder/Project Grant: |
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