Static charged perfect fluid spheres in general relativity

Interior perfect fluid solutions for the Reissner-Nordstrom metric are studied on the basis of a new classification scheme. General formulas are found in many cases. Explicit new global solutions are given as illustrations. Known solutions are briefly reviewed.Comment: 23 pages, Revtex (galley), journal version, to appear in Phys.Rev.

Galaxy Counterparts of metal-rich Damped Lyman-alpha Absorbers - I: The case of the z=2.35 DLA towards Q2222-0946

We have initiated a survey using the newly commissioned X-shooter spectrograph to target candidate relatively metal-rich damped Lyman-alpha absorbers (DLAs). The spectral coverage of X-shooter allows us to search for not only Lyman-alpha emission, but also rest-frame optical emission lines. We have chosen DLAs where the strongest rest-frame optical lines ([OII], [OIII], Hbeta and Halpha) fall in the NIR atmospheric transmission bands. In this first paper resulting from the survey, we report on the discovery of the galaxy counterpart of the z_abs = 2.354 DLA towards the z=2.926 quasar Q2222$-0946. This DLA is amongst the most metal-rich z>2 DLAs studied so far at comparable redshifts and there is evidence for substantial depletion of refractory elements onto dust grains. We measure metallicities from ZnII, SiII, NiII, MnII and FeII of -0.46+/-0.07, -0.51+/-0.06, -0.85+/-0.06, -1.23+/-0.06, and -0.99+/-0.06, respectively. The galaxy is detected in the Lyman-alpha, [OIII] lambda4959,5007 Halpha emission lines at an impact parameter of about 0.8 arcsec (6 kpc at z_abs = 2.354). We infer a star-formation rate of 10 M_sun yr^-1, which is a lower limit due to the possibility of slit-loss. Compared to the recently determined Halpha luminosity function for z=2.2 galaxies the DLA-galaxy counterpart has a luminosity of L~0.1L^*_Halpha. The emission-line ratios are 4.0 (Lyalpha/Halpha) and 1.2 ([OIII]/Halpha). The Lyalpha line shows clear evidence for resonant scattering effects, namely an asymmetric, redshifted (relative to the systemic redshift) component and a much weaker blueshifted component. The fact that the blueshifted component is relatively weak indicates the presence of a galactic wind. The properties of the galaxy counterpart of this DLA is consistent with the prediction that metal-rich DLAs are associated with the most luminous of the DLA-galaxy counterparts.Comment: 9 pages, 7 figures. Accepted for publication in MNRA

Evaluation of Devasthal site for optical astronomical observations

Based on an extensive site survey conducted during 1980-1990 in the Shivalik Hills of the Central Himalayan range, a promising site Devasthal has been identified. The longitude and latitude of Devasthal Peak are 79° 41′ E and 29° 23′ N. It is situated at an altitude of 2540 m and about 50 km by road from Nainital towards East. The surroundings of Devasthal are thinly populated and it is logistically well suited for establishing modern optical observational facilities. The prevailing wind direction at Devasthal is NW. For a large fraction of the night time, variation in the ambient temperature was less than a degree and wind speed was less than 10 m/s. During spectroscopic nights (> 200 in a year) relative humidity is less than 80% for about 70% of the time. During 1997 and 1998 seeing measurements using differential image motion techniques have been carried out close to ground at two locations namely Site 1 and Site 2 in Devasthal. Our observations for Site 1 carried over 88 nights yield a median seeing value of 1.\!\!^{\prime\prime} 4. For Devasthal Site 2 observations carried over 37 nights yield a median seeing value of 1.\!\!^{\prime\prime} 1. Devasthal Site 2 has therefore been selected for locating a modern 3 m optical telescope