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K. K. Scaria 《Astrophysics and Space Science》1984,103(2):207-218
A study of the mean photographic magnitudes of RR Lyrae variables in galactic globular clusters has shown that the luminosity of RR-ab variables decreases with period. It is found that RR-ab variables, in the cluster Centauri, whose distances are greater than 8 arc min from the centre of the cluster, are less luminous than such variables seen in the inner region. The possibility of two transition periods for RR-ab variables, one near 0
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9, is suggested to explain the sharp boundaries of the instability gap and of the periods of RR Lyrae variables. It is also shown that the inner RR Lyrae variables in Centauri are more massive than the outer ones. 相似文献
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K. R. Sivaraman M. Jayachandran K. K. Scaria G. S. D. Babu S. P. Bagare A. P. Jayarajan 《Journal of Astrophysics and Astronomy》1984,5(2):149-158
During the eclipse of 1980 February 16 we photographed the solar corona at an effective wavelength of 6300 å. Using a quadruple camera we also obtained the coronal pictures in polarized light for four Polaroid orientations. We have used these observations to derive the coronal brightness and polarization and from these the electron densities in the corona out to a distance of about 2.5 R⊙ from the centre of the disc. The coronal brightness matches well with that of the corona of 1958 October 12. 相似文献
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K. K. Scaria 《Solar physics》1983,85(2):235-236
Unsharp masking may be used for better reproduction of over-exposed solar corona photographs. 相似文献
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Photoelectric aperture-photometry ofω Cen inU, B, V, R andI bands has established that the cluster is bluer between 2 arcmin and 4 arcmin from the centre, than it is elsewhere. The
difference inB - I colour between the centre and this blue zone is ≃ 0.45 mag. The core radius is found to be dependant on the wavelength band
chosen for observation, the smallest core radius being for theI band. Equidensitometry ofω Cen inB, V and infrared bands shows a wavelength dependence with the cluster being nearly spherical in the infrared band. It shows a
maximum ellipticity around 3 arcmin from the cluster centre. The blue contribution in this zone comes from both a diffuse
background of unresolved stars and an increase in the relative abundance of horizontal branch (HB) stars. The similarity between
the diffuse background and the HB stars has been demonstrated. A photographic subtraction technique is used to study the distribution
of HB stars in the cluster.
Results of equidensitometry of the cluster 47 Tuc, obtained in the present study, are compared with the earlier results of
photoelectric photometry. Here too an increase in ellipticity is associated with an increase in the blueness of the cluster.
All globular clusters studied so far for ellipticity show a similarity in the dependence of the ellipticity on the distance
from the centre. The ellipticity has small values near the centre and in the outer regions, with the maximum value in between.
We suggest that the red stars in globular clusters have a nearly spherical distribution. The blue stars form a bulge around
the core with a more elliptical distribution and a different orientation. A similarity between the ellipticity aspects of
both the globular clusters and rotation in the nucleus of M 31 is pointed out; the M 31 nucleus may thus show a bluer colour
and smaller UV excess around the region where the rotation curve shows a peak.
An erratum to this article is available at . 相似文献
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