Correlating Intrinsic Stellar Parameters with Mg ii Self-reversal Depths
The Mg ii h&k emission lines (2803, 2796 Å) are a useful tool for understanding stellar chromospheres and transition regions due to their intrinsic brightness, relatively low interstellar medium (ISM) absorption interference, and abundance of archival spectra available. Similar to...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad22da |
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| Summary: | The Mg ii h&k emission lines (2803, 2796 Å) are a useful tool for
understanding stellar chromospheres and transition regions due to their
intrinsic brightness, relatively low interstellar medium (ISM) absorption
interference, and abundance of archival spectra available. Similar to other
optically thick chromospheric emission lines such as H i Ly α , Mg ii emissions commonly present with a
self-reversed line core, the depth and shape of which vary from star to star. We
explore the relationship between self-reversal and the stellar atmosphere by
investigating the extent to which fundamental stellar parameters affect
self-reversal. We present a search for correlations between photospheric
parameters such as effective temperature, surface gravity, and metallicity with
the Mg ii k self-reversal depth for a group of 135 FGKM main-sequence
stars with high-resolution near-ultraviolet spectra from the Hubble Space
Telescope. We modeled the observed Mg ii k line profiles to correct for
ISM attenuation and recover the depth of the emission line’s self-reversal in
relation to the intensity of the line. We used the PHOENIX atmosphere code to homogeneously determine
the stellar parameters by computing a suite of stellar atmosphere models that
include a chromosphere and transition region, and using archival photometry to
guide the models of each star. We quantify the sensitivity of the visible and
near-infrared photometry to chromospheric and photospheric parameters. We find
weak trends between Mg ii k self-reversal depth and age, rotation
period, Mg ii luminosity, temperature, and mass. All stars in our
sample older than ∼2 Gyr or rotating slower than ∼10 days exhibit
self-reversal. |
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| ISSN: | 1538-4357 |