{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T19:12:03Z","timestamp":1772219523474,"version":"3.50.1"},"reference-count":48,"publisher":"American Astronomical Society","issue":"2","license":[{"start":{"date-parts":[[2017,2,21]],"date-time":"2017-02-21T00:00:00Z","timestamp":1487635200000},"content-version":"vor","delay-in-days":1,"URL":"https:\/\/iopscience.iop.org\/page\/copyright"},{"start":{"date-parts":[[2017,2,21]],"date-time":"2017-02-21T00:00:00Z","timestamp":1487635200000},"content-version":"tdm","delay-in-days":1,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"}],"content-domain":{"domain":["iopscience.iop.org"],"crossmark-restriction":false},"short-container-title":["ApJ"],"published-print":{"date-parts":[[2017,2,20]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>We describe the structural, stellar population and gas properties of the nearest ultra diffuse galaxy discovered so far: UGC 2162 (<jats:italic>z<\/jats:italic>\u00a0=\u00a00.00392; <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn1.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> kpc; <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn2.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula>\u00a0=\u00a024.4\u00a0\u00b1\u00a00.1 mag arcsec<jats:sup>\u22122<\/jats:sup>; <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn3.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula>\u00a0=\u00a00.33\u00a0\u00b1\u00a00.02). This galaxy, located at a distance of 12.3(\u00b11.7) Mpc, is a member of the M77 group. UGC 2162 has a stellar mass of <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn4.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> \u00d7\u00a010<jats:sup>7<\/jats:sup>\n                  <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn5.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> and is embedded within a cloud of HI gas \u223c10 times more massive: \u223c1.9(\u00b10.6)\u00a0\u00d7\u00a010<jats:sup>8<\/jats:sup>\n                  <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn6.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula>. Using the width of its HI line as a dynamical proxy, the enclosed mass within the inner <jats:italic>R<\/jats:italic>\u00a0\u223c\u00a05 kpc is \u223c4.6(\u00b10.8)\u00a0\u00d7\u00a010<jats:sup>9<\/jats:sup>\n                  <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn7.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> (i.e., M\/L \u223c 200). The estimated virial mass from the cumulative mass curve is \u223c8(\u00b12)\u00d710<jats:sup>10<\/jats:sup>\n                  <jats:italic>M<\/jats:italic>\n                  <jats:sub>\u2299<\/jats:sub>. Ultra-deep imaging from the IAC Stripe82 Legacy Project show that the galaxy is irregular and has many star-forming knots, with a gas-phase metallicity around one-third of the solar value. Its estimated star-formation rate is \u223c0.01 <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn8.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> yr<jats:sup>\u22121<\/jats:sup>. This SFR would double the stellar mass of the object in \u223c2 Gyr. If the object were to stop forming stars at this moment, after a passive evolution, its surface brightness would become extremely faint: <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn9.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> 27 mag arcsec<jats:sup>\u22122<\/jats:sup> and its size would remain large <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn10.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> 1.8 kpc. Such faintness would make it almost undetectable to most present-day surveys. This suggests that there could be an important population of <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn11.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> 10<jats:sup>7<\/jats:sup>\n                  <jats:inline-formula>\n                     <jats:tex-math>\n\n<\/jats:tex-math>\n                     <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"apjaa5cbbieqn12.gif\" xlink:type=\"simple\"\/>\n                  <\/jats:inline-formula> \u201cdark galaxies\u201d in rich environments (depleted of HI gas) waiting to be discovered by current and future ultra-deep surveys.<\/jats:p>","DOI":"10.3847\/1538-4357\/aa5cbb","type":"journal-article","created":{"date-parts":[[2017,2,21]],"date-time":"2017-02-21T18:13:43Z","timestamp":1487700823000},"page":"191","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":85,"title":["The Nearest Ultra Diffuse Galaxy: UGC 2162"],"prefix":"10.3847","volume":"836","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8647-2874","authenticated-orcid":false,"given":"Ignacio","family":"Trujillo","sequence":"first","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3849-3467","authenticated-orcid":false,"given":"Javier","family":"Roman","sequence":"additional","affiliation":[]},{"given":"Mercedes","family":"Filho","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1123-6003","authenticated-orcid":false,"given":"Jorge 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Nearest Ultra Diffuse Galaxy: UGC 2162","name":"article_title","label":"Article Title"},{"value":"The Astrophysical Journal","name":"journal_title","label":"Journal Title"},{"value":"paper","name":"article_type","label":"Article Type"},{"value":"\u00a9 2017. The American Astronomical Society. All rights reserved.","name":"copyright_information","label":"Copyright Information"},{"value":"2017-01-12","name":"date_received","label":"Date Received","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2017-01-25","name":"date_accepted","label":"Date Accepted","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2017-02-21","name":"date_epub","label":"Online publication date","group":{"name":"publication_dates","label":"Publication dates"}}]}}