Solar physics at the Kodaikanal Observatory: A Historical Perspective

This article traces the birth and growth of solar physics at the Kodaikanal Observatory of the Indian Institute of Astrophysics, Bangalore, India. A major discovery took place here in 1909 by John Evershed who detected radial outflow of matter in the penumbra of sunspots. Major developments at the Observatory since its inception in 1899 as well as the scientific results are highlighted.Comment: 26 pages, 7 figures To appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 200

Identification of Beryllium Hydride Isotopomer Lines in Sunspot Umbral Spectra

A high resolution spectrum of FTS sunspot umbra of NSO/Kitt Peak was used to conduct a search for the molecular absorption lines due to BeH, BeD and BeT isotopomers. Analysis led to estimates of identification of the molecular lines of bands A - X (0,0), (1,1) and (2,2) for BeH, A - X (0,0), (1,1), (2,2) and (3,3) for BeD and of A - X (0,0), (1,1) and (2,2) for BeT. Among the identified lines, those which are well resolved were selected for measurements to calculate equivalent widths. The values of effective rotational temperature T were estimated for bands A - X(1,1) and (2,2) of BeH, A - X(1,1) of BeD and A - X(2,2) of BeT to be 4228K, 4057K, 3941K and 3243K respectively

On the Effective Temperature of Sunspot Umbrae using Beryllium Hydride Isotopomer Lines

A search for fourteen bands of the visibleand infrared systems of the beryllium hydride isotopomers, in addition to the previously identified bands A - X(0, 0; 1, 1; 2, 2) for BeH, A - X(0, 0; 1, 1; 2, 2) for BeD and A - X(0, 0; 1, 1; 2, 2) for BeT molecules was conducted. The equivalent widths were measured for the well isolated identified lines of the strongest band and the effective temperatures were estimated for the systems for which the presence of hints is confirmed

Astrophysical molecule CN : vibronic transition probability parameters

Abstract. Astrophysical applications are broadened by the emerging consensus on the vibration-electronic (vibronic) transition probability parameters such as Franck -Condon (FC) factors & r -centroids of some molecular species like CN , which could be useful in the identification of molecular lines and in the estimation of relative abundance of the species in various celestial bodies especially in the interstellar medium. Such important parameters, that is FC factors and r -centroids, have been computed by a reliable numerical integration procedure for the bands of E i systems of astrophysical molecule CN , using a suitable potential. For E − X system, the improved values of FC factors from the revised molecular constants are given along with the already reported values

Detection of short-period coronal oscillations during the total solar eclipse of 24 october, 1995

An experiment to search for short-period oscillations in the solar corona was conducted during the total solar eclipse of 1995 October 24 at Kalpi, India. The intensity in the continuum, centred around 5500 Å and with a passband having a half-width of 240 Å, was recorded at a counting rate of 20 Hz using a thermoelectric-liquid cooled photomultiplier. The power-spectrum analysis of the data reveals that most of the power is contained in 6 frequencies below 0.2 Hz. A least-square analysis gives the periods of the 6 frequency components to be 56.5, 19.5, 13.5, 8.0, 6.1, and 5.3 s. These oscillations are found to be sinusoidal, and their amplitudes are found to lie in the range 0.2-1.3% of the coronal brightness. Assuming these oscillations to be fast magnetosonic modes, the calculations indicate the availability of enough flux for the heating of the active regions in the solar corona

Intensity measurements and relative band strengths of the fluorescent bands of the (B-X) system of I2

Relative integrated intensities of a few bands in the vibrational structure of the B-X fluorescent system of molecular iodine have been measured by the technique of photographic photometry. Reliable values of Franck-Condon factors and r-centroids given recently by Tellinghuisen have been employed to evaluate the variation of electronic transition moment with internuclear separation. The variation is found to be Re(r̄) = const.(1−0.6930r + 0.1201r2) in the range 2.76 < r < 2.81 Å. Smoothed arrays of band strengths are presented for the bands. The effective vibrational temperature of the source is found to be 340 ± 55 K

Dissociation energy of CO + from the true potential energy curve

The dissociation energy for the ground state of CO + has been estimated to be 9·30±0·35 eV by the method of curve fitting. The three parameter Lippincott potential function has been used for fitting with the RKRV curve. © 1978 Indian Academy of Sciences

Dissociation energy for the ground state of AlO from true potential energy curve

The true potential energy curve for the ground state of AlO has been extended up to the observed vibrational levels v = 22 using revised vibrational constants. The dissociation energy for the ground state of AlO has been estimated to be 4.15 ± 0.05 eV by the method of curve fitting. The Lippincott potential function has been used for fitting with the RKRV curve

Abnormal rotation rates of sunspots and durations of associated flares

Context. Short-duration and long-duration flares are important in terms of their association with coronal heating and coronal mass ejections, respectively. Sunspot motions in the photosphere have been known to be associated with flare occurrences. Aims. We study the association between the abnormal rotation rates (longitudinal displacement in a given latitude in contrast with the rotation of spots around their umbral centre) of sunspots and flare duration. Methods. We compute the rotation rates of sunspots for different days during their evolution. We consider rotation rates that are in excess of one standard deviation as abnormal rotation rates. Also, the duration of time between the initial and final stages of the flares are computed. Results. Using Kodaikanal Observatory white light picture and GOES soft X-ray flare data, we find that a good association with a high significance exists between abnormal rotation rates of sunspots and flare durations. In contrast, we find that duration of flare is independent of sunspot area. Conclusions. The present study suggests that sub-surface dynamics plays a dominant role in determining the duration and rate of dissipation of energy during flares