Results 151 to 160 of about 904 (176)
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Solar Physics, 1992
Recent observations of brightness variations on the sun during the solar cycle have motivated us to re-examine the widely held view that cool, dark starspots, covering a significant fraction of the star, are the centers of magnetic activity on BY Dra stars.
Bj�rn R. Pettersen +2 more
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Recent observations of brightness variations on the sun during the solar cycle have motivated us to re-examine the widely held view that cool, dark starspots, covering a significant fraction of the star, are the centers of magnetic activity on BY Dra stars.
Bj�rn R. Pettersen +2 more
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Astrophysics, 2014
Long-term, multiband photometric observations of 8 young PMS stars are used to construct models for their starspots. It is shown that the average density of starspots is up to 40 % of the total surface of a star (V824 Ara), while the difference in temperatures between a quiet photosphere and a spot ranges from 870 K (AB Dor) to 1700-1800 K (PZ Tel ...
I Yu Alekseev, Alekseev I Yu
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Long-term, multiband photometric observations of 8 young PMS stars are used to construct models for their starspots. It is shown that the average density of starspots is up to 40 % of the total surface of a star (V824 Ara), while the difference in temperatures between a quiet photosphere and a spot ranges from 870 K (AB Dor) to 1700-1800 K (PZ Tel ...
I Yu Alekseev, Alekseev I Yu
exaly +2 more sources
Astronomische Nachrichten, 2002
The discovery of exoplanets has resulted from a significant increase in the precision of stellar radial velocity measurements. In the past decade this precision has improved from several hundreds of ms–1 to a few ms–1. In the near future astrometric measurements will make a similar increase in their precision by factors of several hundred.
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The discovery of exoplanets has resulted from a significant increase in the precision of stellar radial velocity measurements. In the past decade this precision has improved from several hundreds of ms–1 to a few ms–1. In the near future astrometric measurements will make a similar increase in their precision by factors of several hundred.
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The formation of sunspots and starspots
Astronomische Nachrichten, 2002The spatial scale of large solar active regions and many of their observed features indicate that they originate from the emergence of a coherent magnetic structure of rather well-ordered toroidal magnetic flux in the solar interior. Numerical simulations of the instability of magnetic flux tubes and their rise through the convection zone are ...
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Astronomische Nachrichten, 2002
I present a literature survey of the currently available Doppler images of cool stars. The 65 individual stars with Doppler images consist of 29 single stars and 36 components in close binaries. Out of the total, 31 were observed only once but 12 stars are (or were) being monitored for years. Each image for each star is identified with the time when it
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I present a literature survey of the currently available Doppler images of cool stars. The 65 individual stars with Doppler images consist of 29 single stars and 36 components in close binaries. Out of the total, 31 were observed only once but 12 stars are (or were) being monitored for years. Each image for each star is identified with the time when it
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SADE: The starspot and dynamo explorer
Advances in Space Research, 2003Abstract We propose a mission called SADE, the Starspot And Dynamo Explorer, to study dynamo activity in nearby late-type stars. The onboard instruments will be a Ca-K telescope for magnetically dominated chromospheric emission, and an X-ray grazing incidence telescope to study coronal emission.
Martens, P. +6 more
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Starspot mapping with robotic telescopes
Astronomische Nachrichten, 2002Robotic telescopes for photometry and imaging have been around for several years. They have been very valuable to monitor light variations due to changing spot patterns on active stars. Two new spectroscopic robotic telescopes will come online in the near future, one in Tenerife and one in Arizona.
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The magnetic structure of sunspots and starspots
Astronomische Nachrichten, 2002The single most important quantity determining the properties of sunspots and presumably starspots is their magnetic field. First an overview of the magnetic structure of sunspots is given, some of the progress made in recent years is described and some of the unsolved questions are pointed out. Both observational and theoretical aspects are dealt with.
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The 1973 RT Andromedae Starspot
Publications of the Astronomical Society of Australia, 1991AbstractAn analysis of 1973 RT Andromedae B and V light curves is presented. The results are fitted into a spot evolution sequence found in a previous study which used the same technique on different data. The new values of the system’s physical parameters are in general agreement with the earlier ones.
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