Results 101 to 110 of about 302 (161)
, 1988 The ratio of the emission line fluxes for the C II and C IV lines in the lower transition regions (T = 30,000 to 100,000 K) between stellar chromospheres and transition layers is shown to depend mainly on the temperature gradient in the line emitting ...
Boehm-Vitense, Erika
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ON THE VALIDITY OF ACOUSTICALLY HEATED CHROMOSPHERE MODELS
, 2020 Theoretical models of solar and stellar chromospheres heated by acoustic waves have so far been constructed by using time-dependent, one-dimensional, radiation-hydrodynamic numerical codes that are based on the approximation of plane-parallel geometry ...
W Kalkofen +3 more
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Doppler-shifted Signatures in the Chromospheric Line Profiles of II Pegasi
The Astrophysical JournalStellar flares are frequently accompanied by prominence eruptions, coronal mass ejections (CMEs), and other forms of plasma motion. Based on the long-term high-resolution spectroscopic monitoring data set of the RS CVn-type star II Pegasi (II Peg), we ...
Dongtao Cao, Shenghong Gu
doaj +1 more source
Further Investigation on Chromospheric Activity Patterns of the RS Canum Venaticorum Star V711 Tauri
The Astronomical JournalWe present new long-term spectroscopic observations of the very active RS Canum Venaticorum (RS CVn) star V711 Tauri (V711 Tau), obtained during several observing runs from 2005 to 2021.
Dongtao Cao, Shenghong Gu
doaj +1 more source
, 1986 Major advances in our understanding of non-radiative heating and other activity in stars cooler than T sub eff = 10,000K has occured in the last few years.
Linsky, J. L.
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Multiwavelength optical observations of chromospherically active binary systems
, 2007 Context.This is the fifth paper in a series aimed at studying the chromospheres of active binary systems using several optical spectroscopic indicators to obtain or improve orbital solution and fundamental stellar parameters.
Gálvez, M. C. +9 more
core +1 more source
The California Legacy Survey. V. Chromospheric Activity Cycles in Main-sequence Stars
The Astrophysical Journal Supplement SeriesWe present optical spectroscopy of 710 solar neighborhood stars collected over 20 years to catalog chromospheric activity and search for stellar activity cycles.
Howard Isaacson +33 more
doaj +1 more source
Crowning the Queen: Membership, Age, Rotation, and Activity for the Open Cluster Coma Berenices
The Astrophysical JournalDespite being only 85 pc away, the open cluster Coma Berenices (Coma Ber) has not been extensively studied. This is due in part to its sparseness and low proper motion, which together made Coma Ber’s membership challenging to establish.
M. A. Agüeros +10 more
doaj +1 more source
Influence of chemi-ionization and chemi-recombination processes on hydrogen line shapes in M dwarfs
, 2007 Aims.We study the influence of chemi-ionization in ${\rm H}^{*}(n) + {\rm H}(1{\rm s})$ collisions and inverse chemi-recombination processes on the population of higher levels and consequently on profiles of hydrogen lines in the atmospheres of late type
Lj. M. Ignjatović +5 more
core +1 more source
The Astrophysical JournalLow-mass (≲1.2 M _⊙ ) main-sequence stars lose angular momentum over time, leading to a decrease in their magnetic activity. The details of this rotation–activity relation remain poorly understood, however.
Alejandro Núñez +8 more
doaj +1 more source