Tag Archive | SDSS

Post-starburst galaxies paper submitted!

Today’s blog post is from Ivy Wong:

Hello Zoo-ites!  I’m a work colleague of Kevin’s and I just recently submitted a Galaxy Zoo paper too. I just wanted to let you know all about it because I also wanted to thank you all for the great work which you’ve done in classifying so many galaxies. I am quite excited by the results and hope that it will be published soon.  My research interests spans from understanding the processes of star formation to the evolution of galaxies and the Universe as we see today.

photoIvy’s research assistants

The Galaxy Zoo paper that I just submitted consists of nearby galaxies which appear to be transitioning from being  star-forming to  passively-evolving galaxies.  In particular, I looked at a sample of post-starburst galaxies (PSG). These PSG had a recent burst of star formation but they have since ceased forming stars.  Thanks to the compilation of all the morphology classifications and the merger votes produced by the Zoo-ites, we were able to determine that most of these PSG have an indeterminate morphology with a higher fraction of interaction than regular spirals or ellipticals. It is possible that these interactions were responsible for the burst of star formation as well as the disturbed galaxy morphology.

The majority of PSG are low-mass but most of their stellar distribution already resemble those of ellipticals. However, they are still somewhat “green” and will likely turn red once the starlight of the youngest population of stars start to fade.  Therefore these nearby PSG  will probably end up as redder, low-mass and more passively-evolving galaxies.  This result agrees with previous works asserting that the most massive and passively-evolving galaxies were formed at earlier times in the history of the Universe.

The Sunflower of Canes Venatici

This galaxy is featured in LizPeter’s OOTD for 24th of July 2010.


M63 from the SDSS

This is Messier 63, though I much prefer its other name, the sunflower galaxy. It’s a wonderful dusty spiral galaxy lying 22.9 million light years away from Earth in the constellation Canes Venatici. It’s one of 7 galaxies bound gravitationally together in the M51 group, and according to Wikipedia, it is one of the first objects to be seen to have spiral arms. This was pointed out in 1845 by William Parsons in a time when these objects were thought to be ‘spiral nebulae’ in our own galaxy, and not galaxies themselves. SIMBAD also claims that there is a cluster of stars lying in the foreground of the galaxy.

There are some brilliant Hubble Legacy images and spectra here, and some more from assorted observatories here!

Markarian and the Blob

Today’s OOTW features an OOTD written by Alice on the 15th of July.

117 million light years away there lies a Markarian galaxy and a very interesting companion. As Alice says in her OOTD, these Markarians are galaxies that emit strongly in ultraviolet and visible light, and are often a host to AGN.

During the observation run at Kitt Peak the Galaxy Zoo team had some spare telescope time going after observing a list of Voorwerpjes, so Bill Keel asked Zooites on the forum to provide objects to get a spectrum for:

MRK 490

MRK 490 and its blue companion.

The bright blue blobby companion just above the Markarian galaxy MRK 490 centred in the picture above was one such object that was observed. The companion is brimming with new stars as shown by the huge emission line (amongst others) of OIII at around 5000 angstroms in the spectrum below, the object is very close to the galaxy below it going by their redshift, so it is suspected to be interacting with it!

Spectrum for MKN 490's companion

Spectrum for MKN 490's companion; click for larger image.

The universe on a carpet (live from the SDSS-III meeting)

Greetings from the Sloan Digital Sky Survey III meeting in Princeton! Today is the third and final day of the meeting, where we are planning the next year of operations for the Sloan Digital Sky Survey III (SDSS-III). The original SDSS, of course, provided all the beautiful galaxy pictures that you see in Galaxy Zoo; SDSS-III is an extension of that survey that extend the mission – and keep me quite busy! – until 2015.

The meeting is in the Astronomy Department in Peyton Hall at Princeton University. This is the first time I’ve been here since coming with the Brown University Band in 1996, and I had forgotten what a nice campus this is. And they’ve made an addition to the astronomy building that is the coolest thing ever – see this photo:

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