PROPER MOTION of the LEO II DWARF GALAXY BASED on HUBBLE SPACE TELESCOPE IMAGING

Slawomir Piatek, Carlton Pryor, Edward W. Olszewski

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

This 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 mas century-1 and in the Galactic coordinate system it is mas century-1. The implied space velocity with respect to the Galactic center is km s-1 or, expressed in Galactocentric radial and tangential components, km s-1. The space velocity implies that the instantaneous orbital inclination is 68, with a 95% confidence interval of . 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.

Original languageEnglish (US)
Article number166
JournalAstronomical Journal
Volume152
Issue number6
DOIs
StatePublished - Dec 2016

Keywords

  • galaxies: dwarf
  • galaxies: individual (Leo II)
  • proper motions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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