Results 81 to 90 of about 146,288 (166)
The Influence of Chromospheric Activity on Line Formation
The Astrophysical JournalOne of the primary sources of stellar spectral variability is magnetic activity. While our current understanding of chromospheric activity is largely derived from specific lines sensitive to chromospheric heating, such as the Ca ii H and K doublet ...
Mariela C. Vieytes +2 more
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An interpretation of cycle periods of stellar chromospheric activity
The Astrophysical Journal, 1993 We propose (P cyc /P rot ) 2 , the square of the ratio of the characteristic oscillatory timescales of stellar chromospberic activity to the rotation period, as a useful parameterization of the stellar activity cycle and as the observational equivalent of the theoretical dynamo number, N D . (P cyc /P rot ) 2 can be obtained observationally from 25 yr
W. H. Soon, S. L. Baliunas, Q. Zhang
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Betelgeuse: Detection of the Expanding Wake of the Companion Star
The Astrophysical JournalRecent analyses conclude that Betelgeuse, a red supergiant star (HD 39801), likely has a companion object with a period of ∼2000 days orbiting at only 2.3 R _⋆ , deep in the chromosphere of the supergiant.
Andrea K. Dupree +3 more
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Chromospheric and Coronal Indicators of Stellar Magnetic Structure [PDF]
Symposium - International Astronomical Union, 1983 This paper discusses attempts to derive information on magnetic structure in late-type stars, only from emission fluxes in the cores of the Ca II H and K lines, in UV emission lines and in soft X-rays — and from relations between these emission fluxes. However simpleminded and indirect this approach may seem, it brings out stimulating results.
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Correlating Intrinsic Stellar Parameters with Mg ii Self-reversal Depths
The Astrophysical JournalThe 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
Anna Taylor +4 more
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The Role of Magnetic Fields in Stellar Chromospheres and Transition Regions [PDF]
Symposium - International Astronomical Union, 1983 In this review based largely on observations with the IUE and Einstein satellites, I will summarize the different roles that magnetic fields play in controlling the structure and energy balance in the chromospheres and transition regions of late-type stars.
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Inhomogeneity in the Local ISM and Its Relation to the Heliosphere. [PDF]
Space Sci Rev, 2022 Linsky J +3 more
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Lyα Emission from K and M Dwarfs: Intrinsic Profiles, Variability, and Flux in the Habitable Zone
The Astrophysical JournalLyman-alpha (Ly α ) is the most prominent ultraviolet (UV) emission line in low-mass stars, playing a crucial role in exoplanet atmospheric photochemistry, heating, and escape.
Sarah Peacock +6 more
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The Astrophysical Journal Supplement SeriesAbstract Accurately characterizing the intrinsic stellar photometric noise induced by stellar astrophysics, such as stellar activity, granulation, and oscillations, is of crucial importance for detecting transiting exoplanets. In this study, we investigate the relation between the intrinsic stellar photometric noise, quantified by the ...
Jinghua Zhang +11 more
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Only binary stars can help us actually SEE a stellar chromosphere
, 2007 Binary stars of the \u3b6 Aurigae type (eclipsing systems containing a cool giant plus a hot mainsequence star) offer a unique and highly effective method of probing a stellar chromosphere.
Griffin, R. Elizabeth
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