Low And Moderate Resolution Spectroscopy With An Rca Charge-Coupled Device (CCD)

An RCA buried channel thinned 320x 512 CCD has recently been put into operation as the detector on the blue side of a new double spectrograph used at the Cassegrain focus of the Hale 5.08-meter telescope. The chip is used in a vacuum dewer at a temperature of -132°C. The electronics are essentially the same as those used by Westphal and Gunn for the Texas Instruments 800x 800 CCD's. The readout noise over most of the chip is 46 electrons per pixel, but on one side of the device there are columns with readout noise three times as high as this. The dark current is approximately 85 electrons per pixel per hour and for most purposes can be neglected. When used in a spectroscopic mode with an f/1.5 beam the CCD shows interference patterns with an amplitude of 5 to 20 percent. This pattern occurs most clearly above 5000 Å. It appears to be stable and can be removed by using standard flat-field exposures. At signal levels of a few hundred electrons there are some charge transfer problems. The quantum efficiency between 4000 and 6500 Å is very high and the efficiency at 3260 Å is about 20 percent of that at 4200 Å. Above 6500 A the sensitivity begins to drop steadily

Absolute spectrophotometry in M31 and M32

For a number of places in the bulge of M31 and for two places in M32 photometric scans from 3300 A to 10,600 A have been obtained with the multichannel spectrometer on the 5-meter Hale telescope. The scans show that in both objects the color temperature (particularly shortwards of 5000 A) decreases towards the center and that the strength of the CN bands increases towards the center in both objects in agreement with earlier observations. The new data can all be interpreted in terms of an increase of heavy element abundance towards the center in both objects by a factor probably less than 2 and by an excess of heavy elements in M31 compared to M32 by a factor probably greater than 2, in qualitative agreement with earlier conclusions

Supernova 1972 e in NGC 5253

New absolute energy distributions of the Type 1 supernova 1972e in NGC 5253 extending to about 700 days after maximum light were obtained. A physical model of the expanding envelope, based on the identification of the feature at 6550 A with H-alpha, is proposed. It is described as a differentially expanding atmosphere, with electron density ranging from 10 to the 10th power near maximum light to about 10 to the 7th power, 340 days later, illuminated by a photosphere with temperature in the range 10,000 K to 7,000 K. More than 200 days after maximum, the spectrum was dominated by four features between 4200 A and 5500 A. Three of these four features matched the blended emissions from over 100 lines of Fe II. Possible identifications of the fourth feature with Mg I lambda 4571 or permitted lines of Fe II are also discussed

The spectral energy distribution of NGC 1275

An analysis of absolute spectral energy distributions of interstellar gas for a galaxy (NGC 1275) is presented. Infrared spectra data shows heavy reddening. It is proposed that the interstellar gas may be ionized by shock waves or by nonthermal or stellar radiation. It is suggested, that high velocity, emission-line knots are H2 regions in a Perseus cluster galaxy or intergalactic gas cloud seen in projection against NGC 1275

Low And Moderate Resolution Spectroscopy With An Rca Charge-Coupled Device (CCD)

An RCA buried channel thinned 320x 512 CCD has recently been put into operation as the detector on the blue side of a new double spectrograph used at the Cassegrain focus of the Hale 5.08-meter telescope. The chip is used in a vacuum dewer at a temperature of -132°C. The electronics are essentially the same as those used by Westphal and Gunn for the Texas Instruments 800x 800 CCD's. The readout noise over most of the chip is 46 electrons per pixel, but on one side of the device there are columns with readout noise three times as high as this. The dark current is approximately 85 electrons per pixel per hour and for most purposes can be neglected. When used in a spectroscopic mode with an f/1.5 beam the CCD shows interference patterns with an amplitude of 5 to 20 percent. This pattern occurs most clearly above 5000 Å. It appears to be stable and can be removed by using standard flat-field exposures. At signal levels of a few hundred electrons there are some charge transfer problems. The quantum efficiency between 4000 and 6500 Å is very high and the efficiency at 3260 Å is about 20 percent of that at 4200 Å. Above 6500 A the sensitivity begins to drop steadily

Spectroscopy of the globular clusters in M87

With a velocity dispersion of 370 + or - 50 km/sec the globular cluster system of M87 is kinematically hotter than the stars in the giant elliptical itself. This is consistent with the clusters' shallower density distribution for isotropic orbits. The mean metallicity of the 27 clusters in the sample analyzed here is no more than a factor of 2 more metal rich than the cluster system of the Milky Way, but considerably more metal poowr than the integrated starlight in the field at a radius of 1' from the center of M87. There is no evidence for the existence of young clusters in the system. The mass-radius relation between 1' and 5' required to contain the globular clusters joins on to that required to contain the hot gas around M87

High resolution CCD spectra of stars in globular clusters. Part 2: Metals and CNO in M71

Palomar coude CCD spectra of resolution 0.3 and 0.6 has been used to redetermine abundances in five stars of the relatively metal rich globular cluster M71. The (Fe/H) value is restricted to the limits of -0.6 to -1.0. The largest source of uncertainty is a systematic difference in f-values between those derived via the Holweger-Muller (1974) solar model and the Bell et al. (1976) solar model. If we use absolute f-values measured by the Oxford group (Blackwell et al. 1982) we find Fe/H to lie in the range of -0.6 to -0.75, i.e., as given by using the Bell et al. solar model. The relative abundances of the light elements, i.e., Na through Ca and probably including Ti show an average excess relative to iron of 0.4 dex. The effect of this difference on metal indices derived from broad- and narrow- band photometry is discussed. For three stars we find O/H = -0.6 using absolute f-values. For CN an analysis of individual rotational lines of the 2-0 band of the red system yields lines in the (C/H,N/H) plane that are consistent with either an original C/Fe = N/Fe = 0 or a modest increase in N relative to C due to CN burning and mixing. A search for C-13N was not successful and an uncertain lower limit of C-12/C-13 near 10 was obtained

Optical and infrared spectrophotometry of 18 Markarian galaxies

Slit spectra, spectrophotometric scans and infrared broad band observations are presented. Eight of the program galaxies can be classified as Seyfert galaxies. Arguments are given that thermal, nonthermal and stellar radiation components were present. One group of Seyfert galaxies was characterized both by the presence of a high density region of gas and by a continuum dominated by nonthermal radiation. The continua of the remaining program Seyferts, which did not have a high density region of gas, were dominated by thermal radiation from dust and a stellar continuum. Ten of the galaxies, which are not Seyfert galaxies, are shown to be examples of extragalactic H 2 regions

Photoelectric spectrophotometry of OQ 172 and OH 471

Absolute spectral energy distributions for the large redshift quasars OQ 172 and OH 471 are discussed along with similar data for two other quasars 4C05.34 and PHL 957. Assuming cosmological redshifts, OQ 172 and OH 471 are not as luminous as PHL 957. If these quasars are basically similar and if radiative processes dominate, the strength of Ly alpha and the behavior of the continuum at the Lyman limit strongly suggest that these objects consist of a central ionizing source surrounded by discrete clouds, filaments or a gaseous structure such as a disk. This gaseous matter does not cover the whole solid angle surrounding the source