High spatial and spectral resolution observations have been made over a sunspot (SPO 6403) with the Echelle Spectrograph at the Vacuum Tower Telescope, Sacramento Peak Observatory. Our observed spectra, scanned with SPO's fast microdensitometer, clearly show strengthening of C 2 lines in the penumbra relative to the photosphere and much weakening in the umbra in agreement with the predictions made by our molecular equilibrium calculations (Lee et al. 1981).

The luminosity functions of 12 open clusters are derived for which their membership and the colors of their individual stars have been established by detailed proper motion study and high quality photometric work. The resulting luminosity functions of these clusters are presented and discussed.

Weibull analyses given to the initial mass function (IMF) deduced by Miller and Scalo (1979) have shown that the mass dependence of IMF is an exp [ − α m ] - form in low mass range while in the high mass range it assumes an exp [ − α √ m ] / √ m -form with the break-up being at about the solar mass. Various astrophysical reasonings are given for identifying the exp [ − α m ] and exp [ − α √ m ] / √ m with halo and disk star characteristics, respectively. The physical conditions during the halo formation were such that low mass stars were preferentially formed and those in the disk high mass stars favoured. The two component nature of IMF is in general accord with the dichotomies in various stellar properties.

In order to know how the magnetic field increases with density in interstellar clouds, we have analyzed observations of extinction and polarization for stars in the ρ Oph molecular cloud complex. The size of grains in dense parts of the complex is estimated to be larger than the ones in diffuse interstellar clouds by about 15 percent in radii. Employing the Davis-Greenstein mechanism for grain alignment with this estimated grain size, we have put constraints on the exponent in the field-density relation B ∝ n x : 1 / 5 ≤ x ≤ 1 / 3 . It is concluded that magnetic field in gravitationally contracting clouds increases less steeply than the classical expectation based on the approximation of isotropic contraction with complete frozen-in flux.

Various assumptions used in interpreting the observations of hydrogen recombination lines are critically assessed to confirm the gradient of electron temperature with distance from the galactic center. The total temperature increase from 5 to 13 kpc is about 2,500 K. Among many suggestions, we have singled out the decrease of trace dement abundances with the galactoccntric distance as the most viable cause for the temperature gradient. This will impose an important constraint on evolutionary models of the Galaxy.

Simultaneous observations of high resolution spectra of CaII H, K, λ 8542 a n d λ 8498 have been made over a sunspot umbra (SPO 5007) by means of Sacramento Peak Observatory's HIRKHAD program with the Echelle spectrograph at the Vacuum Tower Telescope. The observed spectra scanned by SPO's fast microphotometer have been reduced for later theoretical interpretations. The reduced profiles, sampled over a region which is thought to be coolest over the spot, are presented in units of absolute intensity. The core intensity ratios of I ( K 3 ) / I ( H 3 ) ; a n d I ( λ 8498 ) / I ( λ 8542 ) arc found to be 1.3 and 1.14, respectively.