Spirals Eat Dwarfs: Galactic Tendrils Shed Light on Evolution of Spiral Galaxies

Spiral galaxies grow by swallowing smaller dwarf galaxies. As they are digested, these dwarf galaxies are severely distorted, forming structures such as surreal tendrils and stellar streams that surround their captors.

Now, for the first time, a new survey has managed to detect the tell-tale tendrils of galactic digestion beyond our immediate cosmic neighborhood, the “Local Group” of galaxies. An international group of researchers led by David Martinez-Delgado (Max Planck Institute for Astronomy and Instituto de Astrofisica de Canarias) has completed a pilot survey of spiral galaxies at distances of up to 50 million light-years from Earth, discovering the tell-tale signs of spirals eating dwarfs.

The ultra-deep images obtained by Delgado and his colleagues open the door to a new round of systematic galactic interaction studies. And remarkably, these cutting-edge results were obtained with the telescopes of ambitious amateur astronomers. The results attest to the power of systematic work that is possible even with smaller instruments: While larger telescopes have the undeniable edge in detecting very distant, but comparatively bright star systems such as active galaxies, this survey provides some of the deepest insight yet when it comes to detecting ordinary galaxies that are similar to our own cosmic home, the Milky Way.

“Stellar Tidal Streams in Spiral Galaxies of the Local Volume: A Pilot Survey with Modest Aperture Telescopes” by D. Martinez-Delgado et al. will be published as a letter in the October issue of the Astronomical Journal.

Electronic preprint: http://arxiv.org/abs/1003.4860

Article and images: http://www.mpia.de/Public/menu_q2.php?Aktuelles/PR/2010/PR100907/PR_100907_en.html