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Discovery of an ultra-diffuse galaxy in the pisces-perseus supercluster

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Martínez Delgado, David and Läsker, Ronald and Sharina, Margarita and Toloba, Elisa and Fliri, Jürgen and Beaton, Rachael and Valls-Gabaud, David and Karachentsev, Igor D. and Chonis, Taylor S. and Grebel, Eva K. and Forbes, Duncan A. and Romanowsky, Aaron J. and Gallego Laborda, J. and Teuwen, Karel and Gómez Flechoso, María de los Ángeles and Wang, Jie and Guhathakurta, Puragra and Kaisin, Serafim and Ho, Nhung (2016) Discovery of an ultra-diffuse galaxy in the pisces-perseus supercluster. Astronomical Journal, 151 (96). ISSN 0004-6256

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Official URL: http://iopscience.iop.org/journal/1538-3881



Abstract

We report the discovery of DGSAT I, an ultra-diffuse, quenched galaxy located 10fdg4 in projection from the Andromeda galaxy (M31). This low-surface brightness galaxy (μV = 24.8 mag arcsec−2), found with a small amateur telescope, appears unresolved in sub-arcsecond archival Subaru/Suprime-Cam images, and hence has been missed by optical surveys relying on resolved star counts, in spite of its relatively large effective radius (Re(V) = 12'') and proximity (15') to the well-known dwarf spheroidal galaxy And II. Its red color (V − I = 1.0), shallow Sérsic index (nV = 0.68), and the absence of detectable Hα emission are typical properties of dwarf spheroidal galaxies and suggest that it is mainly composed of old stars. Initially interpreted as an interesting case of an isolated dwarf spheroidal galaxy in the local universe, our radial velocity measurement obtained with the BTA 6 m telescope (Vh = 5450 ± 40 km s−1) shows that this system is an M31-background galaxy associated with the filament of the Pisces-Perseus supercluster. At the distance of this cluster (~78 Mpc), DGSAT I would have an Re ~ 4.7 kpc and MV ~ −16.3. Its properties resemble those of the ultra-diffuse galaxies (UDGs) recently discovered in the Coma cluster. DGSAT I is the first case of these rare UDGs found in this galaxy cluster. Unlike the UDGs associated with the Coma and Virgo clusters, DGSAT I is found in a much lower density environment, which provides a fresh constraint on the formation mechanisms for this intriguing class of galaxy.


Item Type:Article
Uncontrolled Keywords:galaxies: clusters: general – galaxies: evolution – galaxies: formation – galaxies: photometry
Subjects:Sciences > Mathematics > Astronomy
Medical sciences > Biology > Biomathematics
ID Code:42027
Deposited On:30 Mar 2017 17:36
Last Modified:10 Dec 2018 15:25

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