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Dwarf Spheroidal Galaxies in the M101 Group and Behind it

Karachentsev, I. D.; Makarova, L. N.

We use images from the Hubble Space Telescope to determine the distances to a dozen objects with low surface brightness recently observed around the bright nearby spiral M101. Only two dwarf galaxies, M101-DwA and M101-Dw9, turn out to be actual satellites of M101 at distances of about 7 Mpc. The other objects are probably members of a distant gro…

New Carbon Stars Confirmed in the Digitized First Byurakan Survey Database

Gigoyan, K. K.; Gigoyan, K. S.; Kostandyan, G. R. +2 more

X-Ray Warm Absorber Variability of the Seyfert Galaxy Arakelian 564

Nouh, M. I.; Korany, B.

We studied the variability of warm absorber clouds of ionized gas within AGN for the Seyfert 1 galaxy Arakelian 564. The X-ray spectra for four XMM-Newton observations of this object are analyzed using the EPIC and the RGS instruments. These four observations covered 11 years. The ionization parameter ξ of the absorbing matter changed between obse…