Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 1996
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996phdt.........8s&link_type=abstract
Thesis (PH.D.)--THE UNIVERSITY OF WISCONSIN - MADISON, 1996.Source: Dissertation Abstracts International, Volume: 57-05, Sectio
Astronomy and Astrophysics
Astronomy
7
Scientific paper
This thesis presents measurements of the absolute proper motions of two dwarf spheroidal (dSph) galaxies, Sculptor and Ursa Minor, presumed to be satellites of the Milky Way, relative to background galaxies and QSOs. Until this work, not even the direction of proper motion was known reliably for any dSph. For the absolute proper motion of Ursa Minor I have achieved an accuracy in angular units of 0.009 arcseconds/century, or about 28 km/s at the dSph distance of ~65 kpc. These dSph motions may be used to probe the Galactic gravitational potential for dark matter and to test the existence of dSph "streams" about the Galaxy. In addition, this research yields complete membership surveys down to the horizontal branch, improved color-magnitude diagrams, and precise astrometric data for future multi-object fiber studies. The Sculptor dSph has a space velocity of roughly 220 +/- 125 km/s. Although this measurement is less than twice its uncertainty, a 2.5 sigma error allows for tangential motion in a direction toward the Fornax dSph galaxy. Sculptor remains a possible member of the proposed Fornax-Leo-Sculptor stream, and is less likely to be associated with the Magellanic orbit. A measurement of greater precision was obtained for the Ursa Minor dSph, with a space velocity of 209 +/- 28 km/s. The direction of Ursa Minor's motion (within 1 sigma errors) coincides with its major axis of elongation. Ursa Minor appears to be orbiting the Galaxy in roughly the same direction and sense as the Large Magellanic Cloud, lending support to the theory of significant tidal interactions in the history of Ursa Minor and our Galaxy. If Ursa Minor is indeed bound to the Galaxy, simple modeling suggests that the Galaxy has a gravitational mass of at least {~}8 times 1011 M_odot, adding further support for the presence of dark matter.
No associations
LandOfFree
Proper Motion Studies of the Dwarf Spheroidal Galaxies Sculptor and Ursa Minor. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Proper Motion Studies of the Dwarf Spheroidal Galaxies Sculptor and Ursa Minor., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Proper Motion Studies of the Dwarf Spheroidal Galaxies Sculptor and Ursa Minor. will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1129431