2,390 research outputs found
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
A Definitive Optical Detection of a Supercluster at z = 0.91
We present the results from a multi-band optical imaging program which has
definitively confirmed the existence of a supercluster at z = 0.91. Two massive
clusters of galaxies, CL1604+4304 at z = 0.897 and CL1604+4321 at z = 0.924,
were originally observed in the high-redshift cluster survey of Oke, Postman &
Lubin (1998). They are separated by 4300 km/s in radial velocity and 17
arcminutes on the plane of the sky. Their physical and redshift proximity
suggested a promising supercluster candidate. Deep BRi imaging of the region
between the two clusters indicates a large population of red galaxies. This
population forms a tight, red sequence in the color--magnitude diagram at (R-i)
= 1.4. The characteristic color is identical to that of the
spectroscopically-confirmed early-type galaxies in the two member clusters. The
red galaxies are spread throughout the 5 Mpc region between CL1604+4304 and
CL1604+4321. Their spatial distribution delineates the entire large scale
structure with high concentrations at the cluster centers. In addition, we
detect a significant overdensity of red galaxies directly between CL1604+4304
and CL1604+4321 which is the signature of a third, rich cluster associated with
this system. The strong sequence of red galaxies and their spatial distribution
clearly indicate that we have discovered a supercluster at z = 0.91.Comment: Accepted for publication in Astrophysical Journal Letters. 13 pages,
including 5 figure
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
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
The influence of the combined microwave power and hot air ventilation on the drying kinetics and colour quality of tomato slices
Tomato is one of the most important fruit used as an ingredient in different foods in food processing and preparation. Fresh tomato consists of about 91% of moisture. Tomato has to pass through all three rates of drying (constant, first and second falling rate period) during drying, using hot air ventilation, and requires prolonged time with much of quality changes. In this study, microwave assisted hot air ventilation drying of tomato slices had been considered. Microwave oven working at 2450 MHz, using different power densities (1, 2 and 3 W g-1) was combined with hot air ventilation at 50°C and hot air ventilation drying without microwave power at 40, 50, 70 and 80°C to dry tomato slices down to 10% moisture content. The drying characteristic curve was analyzed to determine the drying time. The tomato slice sample dried faster when subjected to microwave heating, coupled with hot air ventilation at 50°C. The drying times required for tomato slices to reach 10% moisture content were found to be 3.2, 2.5 and 1.3 h, using 1, 2 and 3 W g-1 microwave power densities, coupled with 50°C hot air ventilation, respectively. On the other hand, the drying time of tomato slices to 10% moisture content required 20.5, 13.1, 9.6, 6.8 h for drying at 40, 50, 70 and 80°C, using hot air ventilation without supplementing heating with microwave power. Microwave drying maintained the superior colour of tomato slices after drying period, compared to the other treatments.Key words: Microwave, tomato slice, drying equation, colour, drying rate, moisture content
SINGLE-PLANT STARVATION AND PAIRED-PLANT STARVATION TESTS OF ADULT Neochetina eichhorniae WARNER
Single-plant starvation and paired-plant starvation tests were performed on adult Neochetina eichhorniae to determine the feeding specificity of the insect on the following plants: Eichhornia crassipes, Pistia stratiotes, Hymphaea lotus, Ceratopteris sp, Azolla species, Colocasia esculentus, Vigna sinensis, Talium triangulare, Capsicum annum and Lycopesicom esculentus.The feeding spots of N.    eichhorniae on the different plants were assessed and counted using a hand-counter.  N. eichhorniae adults fed on E. crassipes only, confirming the feeding specificity of the N. eichhorniae to E. crassipes and the safety of other plants growing in the habitat
- …