Proper motions of dwarf spheroidal galaxies from hubble space telescope imaging. V. Final measurement for fornax

Slawomir Piatek, Carlton Pryor, Paul Bristow, Edward W Olszewski, Hugh C. Harris, Mario Mateo, Dante Minniti, Christopher G. Tinney

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

The measured proper motion of Fornax, expressed in the equatorial coordinate system, is (μα, μδ) = (47.6 ± 4.6, -36.0 ± 4.1) mas century-1. This proper motion is a weighted mean of four independent measurements for three distinct fields. Each measurement uses a quasi-stellar object as a reference point. Removing the contribution of the motion of the Sun and of the local standard of rest to the measured proper motion produces a Galactic rest-frame proper motion of (μαGrf, μδGrf) = (24.4 ± 4.6,-14.3 ± 4.1) mas century-1. The implied space velocity with respect to the Galactic center has a radial component of Vr = -31.8 ± 1.7 km s-1 and a tangential component of Vt = 196 ± 29 km s-1. Integrating the motion of Fornax in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 118 (66, 137) and 152 (144, 242) kpc, respectively, where the values in the parentheses represent the 95% confidence intervals derived from Monte Carlo experiments. The eccentricity of the orbit is 0.13 (0.11, 0.38), and the orbital period is 3.2 (2.5, 4.6) Gyr. The orbit is retrograde and inclined by 101° (94°, 107°) to the Galactic plane. Fornax could be a member of a proposed "stream" of galaxies and globular clusters; however, the membership of another proposed galaxy in the stream, Sculptor, has been previously ruled out. Fornax is in the Kroupa-Theis-Boily plane, which contains 11 of the Galactic satellite galaxies, but its orbit will take it out of that plane.

Original languageEnglish (US)
Pages (from-to)818-844
Number of pages27
JournalAstronomical Journal
Volume133
Issue number3
DOIs
StatePublished - Mar 2007

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proper motion
dwarf galaxies
Hubble Space Telescope
galaxies
retrograde orbits
orbits
eccentricity
confidence interval
orbital elements
globular clusters
confidence
sun
intervals
orbitals
experiment

Keywords

  • Astrometry
  • Galaxies: dwarf
  • Galaxies: individual (Fornax)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Proper motions of dwarf spheroidal galaxies from hubble space telescope imaging. V. Final measurement for fornax. / Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

In: Astronomical Journal, Vol. 133, No. 3, 03.2007, p. 818-844.

Research output: Contribution to journalArticle

Piatek, S, Pryor, C, Bristow, P, Olszewski, EW, Harris, HC, Mateo, M, Minniti, D & Tinney, CG 2007, 'Proper motions of dwarf spheroidal galaxies from hubble space telescope imaging. V. Final measurement for fornax', Astronomical Journal, vol. 133, no. 3, pp. 818-844. https://doi.org/10.1086/510456
Piatek, Slawomir ; Pryor, Carlton ; Bristow, Paul ; Olszewski, Edward W ; Harris, Hugh C. ; Mateo, Mario ; Minniti, Dante ; Tinney, Christopher G. / Proper motions of dwarf spheroidal galaxies from hubble space telescope imaging. V. Final measurement for fornax. In: Astronomical Journal. 2007 ; Vol. 133, No. 3. pp. 818-844.
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