Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images

Details Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images

Jul 2007

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007hst..prop11201k&link_type=abstract

HST Proposal ID #11201. Cycle 16

Other

Scientific paper

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in the Magellanic Clouds centered on background quasars. We used these data to determine the proper motions of the LMC and SMC to better than 5% and 15% respectively. These are by far the best determinations of the proper motions of these two galaxies. The results have a number of unexpected implications for the Milky Way-LMC-SMC system. The implied three-dimensional velocities are larger than previously believed, and are not much less than the escape velocity in a standard 10^12 solar mass Milky Way dark halo. Orbit calculations suggest the Clouds may not be bound to the Milky Way or may just be on their first passage, both of which would be unexpected in view of traditional interpretations of the Magellanic Stream. Alternatively, the Milky Way dark halo may be a factor of two more massive than previously believed, which would be surprising in view of other observational constraints. Also, the relative velocity between the LMC and SMC is larger than expected, leaving open the possibility that the Clouds may not be bound to each other. To further verify and refine our results we now request an epoch of WFPC2/PC data for the fields centered on 40 quasars that have at least one epoch of ACS imaging. We request execution in snapshot mode, as in our previous programs, to ensure the most efficient use of HST resources. A third epoch of data of these fields will provide crucial information to verify that there are no residual systematic effects in our previous measurements. More importantly, it will increase the time baseline from 2 to 5 yrs and will increase the number of fields with at least two epochs of data. This will reduce our uncertainties correspondingly, so that we can better address whether the Clouds are indeed bound to each other and to the Milky Way. It will also allow us to constrain the internal motions of various populations within the Clouds, and will allow us to determine a distance to the LMC using rotational parallax.;

Affiliated with

Also associated with

No associations

Rating

Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images 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 Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-780839