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A Keck Survey of Gravitational Lens Systems. I. Spectroscopy of SBS 0909+532, HST 1411+5211, and CLASS B2319+051
We present new results from a continuing Keck program designed to studygravitational lens systems. We have obtained redshifts for three lenssystems, SBS 0909+532, HST 1411+5211, and CLASS B2319+051. For all ofthese systems, either the source or lens redshift (or both) has beenpreviously unidentified. Our observations provide some of these missingredshifts. We find (zl,zs)=(0.830,1.377) for SBS0909+532 (zl,zs)=(0.465,2.811) for HST 1411+5211,although the source redshift is still tentative; and(zl,1,zl,2)=(0.624,0.588) for the two lensinggalaxies in CLASS B2319+051. The background radio source in B2319+051has not been detected optically; its redshift is, therefore, stillunknown. We find that the spectral features of the central lensinggalaxy in all three systems are typical of an early-type galaxy. Theobserved image splittings in SBS 0909+532 and HST 1411+5211 imply thatthe masses within the Einstein ring radii of the lensing galaxies are1.4x1011 and 2.0x1011 h-1Msolar, respectively. The resulting B-band mass-to-lightratio (M/L) for HST 1411+5211 is 41.3+/-1.2 h (M/L)solar, afactor of ~5 times higher than the average early-type lensing galaxy.This large mass-to-light ratio is almost certainly the result of theadditional mass contribution from the cluster CL 3C 295 at z=0.46. Forthe lensing galaxy in SBS 0909+532, we measure(M/L)B=4+11-3 h (M/L)solar,where the large errors are the result of significant uncertainty in thegalaxy luminosity. While we cannot measure directly the mass-to-lightratio of the lensing galaxy in B2319+051, we estimate that(M/L)B is between 3-7 h (M/L)solar.
| Hα Photometry of late-type stars I. F, G and K-type stars north of the equator
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964MNRAS.128..435P&db_key=AST
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| Takýmyýldýz: | Kuzey Taci |
| Sað Açýklýk: | 15h51m26.43s |
| Yükselim: | +33°09'27.6" |
| Görünürdeki Parlaklýk: | 9.125 |
| özdevim Sað Açýklýk: | -8.5 |
| özdevim Yükselim: | -0.2 |
| B-T magnitude: | 9.635 |
| V-T magnitude: | 9.168 |
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