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We examine the metallicity and age of a large set of Sloan Digital Sky Survey/Data Release 6 galaxies that may be blue compact dwarf (BCD) galaxies during quiescence (QBCDs). The individual spectra are first classified and then averaged to reduce noise. The metallicity inferred from emission lines (tracing ionized gas) exceeds by ~0.35 dex the

XMM-Newton observed the accreting millisecond pulsar SAX J1808.4-3658 during its 2008 outburst. We present timing and spectral analyses of this observation, in particular the first pulse profile study below 2keV, and the high-resolution spectral analysis of this source during the outburst. Combined spectral and pulse profile analyses suggest the

We present submillimeter observations of the z= 3.653 quasar SDSS 160705+533558 together with data in the optical and infrared. The object is unusually bright in the far-IR and submillimeter with an IR luminosity of ~1014 L sun. We ascribe this luminosity to a combination of active galactic nucleus (AGN) and starburst emission, with the starburst

We present a new method to solve for the star-formation history (SFH) of a complex stellar population system from the analysis of the color-magnitude diagram (CMD). The SFH is obtained in four steps: i) computing a synthetic CMD, ii) simulating observational effects, iii) parameterization and sampling of the synthetic and observed CMDs, and iv)

We report recent observations of M31 taken with Chandra/ACIS-I on 2009-05-29.1 UT and with Swift/XRT on 2009-06-07.08 UT. In the 4ks Chandra/ACIS-I image, we found a faint transient located at R.A.(J2000)=00h42m26.7s, Decl. (J2000)=+41:13:46.5 with a 90% absolute error of 0.6 arcsec. It is therefore identified as CXOM31 J004226.7+411346. The