PROPER MOTION OF THE LEO II DWARF GALAXY BASED ON HUBBLE SPACE TELESCOPE IMAGING
AffiliationUniv Arizona, Steward Observ
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PublisherIOP PUBLISHING LTD
CitationPROPER MOTION OF THE LEO II DWARF GALAXY BASED ON HUBBLE SPACE TELESCOPE IMAGING 2016, 152 (6):166 The Astronomical Journal
JournalThe Astronomical Journal
Rights© 2016. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractThis article reports a measurement of the proper motion of Leo II, a dwarf galaxy that is a likely satellite of the Milky Way, based on imaging with the Hubble Space Telescope and Wide Field Camera. 3. The measurement uses compact background galaxies as standards of rest in both channels of the camera for two distinct pointings of the telescope, as well as a QSO in one channel for each pointing, resulting in the weighted average of six measurements. The measured proper motion in the the equatorial coordinate system is (mu(alpha), mu(delta))= (-6.9 +/- 3.7, -8.7 +/- 3.9) mas century(-1) and in the Galactic coordinate system it is (mu(l), mu(b)) = (6.2 +/- 3.9, -9.2 +/- 3.7) mas. century(-1). The implied space velocity with respect to the Galactic center is (Pi, Theta, Z) =(-37 +/- 38, 117 +/- 43, 40 +/- 16) km s(-1) or, expressed in Galactocentric radial and tangential components, (V-r, V-tan) = (21.9 +/- 1.5, 127 +/- 42) km s(-1). The space velocity implies that the instantaneous orbital inclination is 68 degrees, with a 95% confidence interval of (66 degrees, 80 degrees). The measured motion supports the hypothesis that Leo. II, Leo. IV, Leo. V, Crater. 2, and the globular cluster Crater fell into the Milky Way as a group.
VersionFinal published version
SponsorsSpace Telescope Science Institute [HST-GO-11697]; National Science Foundation [AST-1313006]