VLBA Sees a Beefier Milky Way

If you’ve been paying attention to the great astronomy news coming out of the AAS meeting in Long Beach, you would know that astronomers have more accurately determined the speed of rotation and size of the Milky Way Galaxy. It seems that now, our spiral home is as massive as our nearest neighbor, the Andromeda Galaxy! The NRAO put out a great press release to coincide with the press conference at the meeting where you can read all about. Of course you can read all about it at your favorite astronomy news site or blog (just to start, you have Space.com, Discovery, Bad Astronomy, Star Stryder, Universe Today, and Spacewriter.) We’ve had some excellent colloquia on this study in Charlottesville, so I’m glad to see it hitting the press.

If you know me, you know I have a soft spot for Very Long Baseline Interferometry (VLBI). This is where I got my start in astronomy as an undergrad. It is the method by which you can link telescopes together over very large distances in order to effectively make one BIG telescope. How big? Well, try the size of the Earth. The NRAO’s Very Long Baseline Array (VLBA) has 10 antennas, eight of which are scattered throughout the mainland US, one in Hawaii, and one in the Caribbean. These long baselines, or distances between telescopes, get you better angular resolution. That is, you can see much finer detail than you can with any other telescope. Something like a thousand times better! With such accurate images, it is possible to make direct distance measurements to astronomical objects using parallax or proper motions. And if there’s one thing that is a pain about astronomy, it is measuring the distance to a point of light that you observe on the sky. The VLBA is especially well suited to this task with 10 identical antennas and a knowledgeable user community.


Me, hanging out inside the dish of the VLBA Pietown Station in 2004. In my PJs.

However, the VLBA has been severely, in my humble opinion, underrated in it’s 15 or so years of operation. It has only been in the last few years that the VLBA has been getting press for mapping the galaxy and determining the distance to other galaxies with such fine precision, better than any method in the optical or other bands. The radio galaxy and quasar communities have been well aware of its potential for some time, however. I had previously done work on polarized quasars and baby radio galaxies, and that was fascinating (and for write-up another day, I suppose.) But the VLBA suffers from budgetary constraints and this wonderful instrument may be shut down soon to be sacrificed for other observatories! Those are the facts of life, I guess. There is only so much money to go around, and very little for astronomy in the grand scheme of things. However, I sincerely hope that the astronomical community recognizes the enormous impact that the VLBA is having and can continue to have if given an extra shot.

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