Results 21 to 30 of about 1,834 (171)

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

Chromosphere of K giant stars Geometrical extent and spatial structure detection

, 2011
We aim to constrain the geometrical extent of the chromosphere of non-binary K giant stars and detect any spatial structures in the chromosphere. We performed observations with the CHARA interferometer and the VEGA beam combiner at optical wavelengths ...
A. Spang, Andretta, Ayres, B. Pichon, Baines, Berio, Bonneau, Brown, Busà, C. Farrington, Carpenter, Chen, Claret, Cuntz, Cuntz, D. Bonneau, D. Mourard, di Benedetto, Diaz-Cordoves, Dyck, Eaton, Eriksson, F. Thévenin, Gustafsson, H. McAlister, Hall, Houdashelt, I. Tallon-Bosc, J. M. Clausse, J. Sturmann, Judge, K. Perraut, Kovacs, L. Sturmann, Linsky, Luck, Massarotti, McWilliam, Meilland, Montes, Morel, Mourard, Mozurkewich, N. Nardetto, N. Turner, O. Chesneau, O. Delaa, P. Berio, P. J. Goldfinger, P. Stee, Perryman, Pietrinferni, R. Ligi, Reimers, Richichi, Simon, Skrutskie, T. Merle, T. ten Brummelaar, ten Brummelaar, van Belle, van Leeuwen, White   +62 more
core   +3 more sources

The Magnetic Field Configuration in Solar and Stellar Chromospheres [PDF]

Symposium - International Astronomical Union, 1983
Calculations are presented for the inhomogeneous magnetic field structure above a stellar photosphere which has magnetic flux tubes located at the downdraughts of its supergranulation pattern. Regions can be delineated where the ambient magnetic energy density is large or small compared with the thermal energy density derived from a model atmosphere ...
U. Anzer, D. J. Galloway
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

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

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

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

HST Observations of Chromospheres in Metal Deficient Field Giants

, 2007
HST high resolution spectra of metal-deficient field giants more than double the stars in previous studies, span about 3 magnitudes on the red giant branch, and sample an abundance range [Fe/H]= -1 to -3.
A. K. Dupree, Barnes T. G., Bates B., Cousins A. W. J., Gondoin P., Graeme H. Smith, Gratton R. G., Johnson H. L., Kemp S. N., Kurucz R. L., Lyons M. A., Mallia E. A., Murray C. A., Pizzolato N., Rutten R. G. M., Sanders W. L., Schrijver C. J., Seaton M. J., Strassmeier K. G., Timothy Q. Li   +19 more
core   +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
openaire   +1 more source