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On the outer boundary of the sunspot penumbra
Kálmán, Béla
Comparison of photographic observations and vector-magnetograph measurements demonstrate that the outer boundary of the sunspot penumbra - even in complex sunspot groups - closely follows the 0.075 T iso-gauss line of the total value of the magnetic field, corresponding approximately to the equipartition value in the photosphere. Radio observation…
Optical positions of 55 radio stars from astrolabe observations from the Yunnan Observatory
Hui, H.; Rui, W.
The observations by the photoelectric astrolabe at Yunnan Observatory relative to the Hipparcos Catalogue and the optical positions of 55 radio stars were obtained from observations between 1991 and 2000. They all resulted from processing the photon counts obtained by means of the astrolabe after the automation of the instrument. There are 46 star…
Coronal and transition region observations of the sun and cool stars
Williams, David Ronan
This thesis presents observations of dynamic events in the outer atmosphere of the Sun and other cool stars. The effect of opacity on ratios of strong transition region lines is investigated for the flare dMe star YZ CMi, and the RS CVn binary Capella. Opacity is shown to be both an important effect in these stars' atmospheres and an important dia…
Polar coronal jets
Raymond, J. C.; Dobrzycka, D.; Cranmer, S. R.
We present ultraviolet spectroscopy of polar coronal jets obtained with the Ultraviolet Coronagraph Spectrometer aboard the Solar and Heliospheric Observatory. They correlate with the Extreme—Ultraviolet Imaging Telescope Fe XII (195Å) and Large Angle Spectrometric Coronagraph white—light jet events. We found that the jets typically undergo two ph…
A minimum in the light curve of the classical symbiotic star YY Her in 2001.
Kolotilov, E. A.; Yudin, B. F.; Tatarnikova, A. A. +1 more
A search for circumstellar material around B-type stars in the Galactic halo
Dufton, P. L.; Keenan, F. P.; Rolleston, W. R. J. +2 more
19 B-type stars, selected from the Palomar-Green Survey, have been observed at infrared wavelengths to search for possible infrared excesses, as part of an ongoing programme to investigate the nature of early-type stars at high Galactic latitudes. The resulting infrared fluxes, along with Strömgren photometry, are compared with theoretical flux pr…
Multi-wavelength Behaviour of III Zw2
Wu, Kinwah; Mason, Keith O.; Salvi, Nikita +2 more
III Zw2 was observed with XMM-Newton in July 2000. Its X-ray spectrum can be described by a power law of photon index Γ~1.7 with a Gaussian line at 6.7KeV. There is no significant evidence of intrinsic absorption within the source or of a soft X-ray excess. Multi-wavelength light curves over a period of 25 years show related variations from the ra…
A Study of AR 9144; A Fast-Growing EFR
Chapman, G. A.
This paper is a study of NOAA region 9144, an emerging flux region (EFR) which grew rapidly beginning 25 August 2000. This region was visible in SOHO data at 0 UT on 25 August 2000 as a small, isolated spot. It was recognizable as an active region with multiple spots by 06:00 UT on the 25th and was a fully developed AR by 24h UT on the …
Search for Star Groups in the Solar Neighborhood
Orlov, V. V.; Kazakevich, E. É.
Two methods are proposed for finding star groups in coordinate and velocity spaces, which were used to investigate stars of the Hipparcos Catalog with known radial velocities in the solar neighborhood with a radius of 125 pc. Thirteen probable nonrandom star groups in coordinate space and five moving groups in velocity space were found. These resu…
How Good are the Predictions for Oscillation Frequencies?
Tripathy, S. C.; Jain, Kiran; Bhatnagar, A.
We have used available intermediate degree p-mode frequencies for solar cycle 23 to check the validity of previously derived empirical relations for frequency shifts (Jain et al., 2000). We find that the calculated and observed frequency shifts during the rising phase of cycle 23 are in good agreement. The observed frequency shift from minimum to …