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Title: More satellites around the nearby spiral galaxy NGC 7331
Author: M. Blauensteiner, I. D. Karachentsev, P. Remmel, P. Riepe, M. E. Sharina, H. Strauss, U. Trulson, T. Zilch

We report the detection of two dwarf galaxies in a projected distance of ~50 kpc from NGC 7331 and suspect the physical nature of dwarfs of this spiral galaxy.

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NGC 7331 (also known as Caldwell 30, UGC 12113 and PGC 69327) is a magnitude +10.4 unbarred spiral galaxy located about 40 million light-years away in the constellation Pegasus.

The galaxy was discovered by the German-British astronomer William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflecting telescope at an old hunting lodge in Datchet on the 5th September 1784.

The galaxy hosted the Type IIL supernova 1959Dand supernova 2014C

Right ascension 22h 37m 04.1s, Declination +34 24' 56"



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Not far from the Andromeda Galaxy, you'll find the fine but overlooked spiral galaxy NGC 7331. Unlike Andromeda, which spans so much sky its hard to take in at once in a telescope, the delicate spiral arms of NGC 7331 fit nicely into a single field of view at moderate magnification. And if you have a good-sized scope, just to the southwest you might glimpse in a single field of view a fascinating quintet of galaxies some 300 million light years from Earth.

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The spiral galaxy NGC 7331, in Pegasus, can be seen with small telescopes under dark skies as a faint fuzzy spot. It is an island universe similar to our own Galaxy (or maybe somewhat larger) and placed at a distance of 50 million light-years. NGC 7331 was discovered by Wilhelm Herschel in 1784, and it shows all its magnificence in long-exposure photographs taken through large telescopes.

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Title: Optical Spectroscopy of the environment of a ULX in NGC 7331
Authors: Pavel K. Abolmasov, Douglas A. Swartz, S. Fabrika, Kajal K. Ghosh, O. Sholukhova, Allyn F. Tennant

Optical photometric and spectroscopic data are presented that show an association of an ultraluminous X-ray source in NGC 7331 with a young star cluster of mass 1.1e5 solar masses and age 4.25 Myr. If the ULX is part of the bright stellar cluster, then the mass of the progenitor of the compact accretor must have been greater than about 40-50 solar masses in order to already have evolved through the supernova stage to a compact object. The companion star is also likely an evolved massive star. The emission line spectrum of the nebula surrounding the cluster can be interpreted as a result of photoionisation by the cluster OB stars with an additional source of shock excitation producing strong [SII], [OI] and NII lines. This additional source appears to be as much as five times more powerful than the supernovae and stellar winds in the cluster can provide. Additional mechanical energy input associated with the ULX itself can help explain the residual shock excited line luminosities of the emission region.

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