Results 31 to 40 of about 164 (131)

Stellar chromospheres and coronae

The Astrophysical Journal, 1981
The basic structural features of the solar chromosphere and corona are identified either with physical properties of the plasma or with properties of the energy input. It is argued that those properties identified with plasma physics should be relatively invariant whereas those identified with the energy input should vary from star to star.
openaire   +1 more source

Physical Parameters and Chromospheric Activity of Eclipsing Binaries Observed by the LAMOST DR10 Survey

The Astrophysical Journal Supplement Series
In this study, we present a comprehensive study of more than 50,000 spectra of 32,257 eclipsing binaries from the LAMOST DR10 survey, including 5200 systems with spectroscopy.
Ansong Shi, Li-yun Zhang, Tianhao Su, Yinpeng Wang, Qi An, Xianming L. Han, Prabhakar Misra, Linyan Jiang, Rui Guo, Qingfeng Pi   +9 more
doaj   +1 more source

Spectral Irradiance Observations and Projections for Solar Cycle 25

Earth and Space Science, Volume 13, Issue 4, April 2026.
Abstract The Ozone Monitoring Instrument (OMI) on the Aura satellite makes near‐daily measurements of solar spectral irradiance (SSI) at wavelengths between 265 and 500 nm for instrument calibration purposes. The low degradation and exceptional stability of OMI's calibration during its lifetime facilitates the creation of a new 18‐year OMI Version 7 ...
Matthew T. DeLand, Sergey V. Marchenko, Judith L. Lean, Odele Coddington   +3 more
wiley   +1 more source

Ultraviolet observations of stellar chromospheric activity

The Astrophysical Journal, 1982
A survey is presented of chromospheric and transition region (TR) line emission in late-type stars obtained with the IUE satellite. A wide variation in TR emission (ions formed near T = 100,000 K) at a given position in the H-R diagram is found, contradicting theories that incorporate only acoustic energy generation and deposition.
L. Hartmann, A. K. Dupree, J. C. Raymond
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Parker Solar Probe Observations of Proton Core‐Beam Distributions in Heliospheric Current Sheet Region: Quasilinear Instability Analysis Combined With Collisional Relaxation

Journal of Geophysical Research: Space Physics, Volume 131, Issue 4, April 2026.
Abstract Parker Solar Probe has been proven as instrumental for the observation of young solar wind. During the encounters E‐07 and E‐08, PSP recorded the core plus beaming protons crossing the heliospheric current Sheet region. When the observed PSP data is plotted in the temperature ratio versus parallel beta space, it is found that the occurrence ...
M. Rashid, P. H. Yoon, J. Huang, C. Salem, M. Sarfraz, S. Alnussirat, R. A. López, J. Seough, H. Xie, D. Larson, R. Livi   +10 more
wiley   +1 more source

Magnetic Activity of TESS Objects Observed in the LAMOST Medium-resolution Spectral Survey

The Astrophysical Journal Supplement Series
A combination of spectroscopic and photometric observations provides an excellent data sample for studying stellar chromospheric activity. We have combined LAMOST medium-resolution spectra with TESS 2 minute light curves and extracted over 530,000 ...
Tianhao Su, Li-yun Zhang, Prabhakar Misra, Xianming L. Han, Yinpeng Wang, Wenjie Li, Zhongzhong Zhu, Qingfeng Pi, Hongpeng Lu   +8 more
doaj   +1 more source

Searching for Rotational X‐Ray Modulation on TIC 277539431

Astronomische Nachrichten, Volume 347, Issue 3, March 2026.
ABSTRACT TIC 277539431, a fast rotating M7 dwarf, was detected to host the highest latitude flare to date at 81°$$ {81}^{{}^{\circ}} $$. Magnetic activity like stellar flares occurring at high latitude indicate occurrence of coronal loops at these latitudes on fully‐convective M dwarfs. In contrast, sunspots usually occur below 30°$$ {30}^{{}^{\circ}} $
Desmond Dsouza, Katja Poppenhäger, Ekaterina Ilin   +2 more
wiley   +1 more source

Heating of Stellar Chromospheres and Transition Regions [PDF]

Symposium - International Astronomical Union, 2004
To explain the heating of stellar chromospheres and transition regions, two classes of heating mechanisms have been considered: dissipation of acoustic and magnetic waves generated in stellar convection zones; and dissipation of currents generated by photospheric motions of surface magnetic fields.
openaire   +1 more source

The California Legacy Survey. VI. The Fate of Activity Cycles in Sun-like Stars

The Astronomical Journal
We analyze the spectra of 91 solar-type G- and K-type main-sequence dwarfs in the solar neighborhood to assess activity trends with stellar properties.
Howard Isaacson, Stephen R. Kane, Brad Carter, Andrew W. Howard   +3 more
doaj   +1 more source

Periodic Density Structures Observed in Ulysses Data: First Results

Journal of Geophysical Research: Space Physics, Volume 131, Issue 3, March 2026.
Abstract Periodic density structures (PDSs) are advecting quasi‐periodic (periodicities between several minutes and several hours) density enhancements observed in the solar wind and corona. There is strong evidence that PDSs are formed at the Sun.
Brent M. Randol, Nicholeen Viall, Larry Kepko, Simone Di Matteo   +3 more
wiley   +1 more source