Physical Sciences and Mathematics Commons^™

Discovery Of An Ultra-Diffuse Galaxy In The Pisces-Perseus Supercluster, David Martínez-Delgado, Ronald Läsker, Margarita Sharina, Elisa Toloba, Jürgen Fliri, Rachael Beaton, David Valls-Gabaud, Igor Karachentsev, Taylor Chonis, Eva Grebel, Duncan Forbes, Aaron Romanowsky, J. Gallego-Laborda, Karel Teuwen, M. Gómez-Flechoso, Jie Wang, Puragra Guhathakurta, Serafim Kaisin, Nhung Ho

Faculty Publications

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 …