Friday Galaxy Blogging : NGC 1365

Feb 23 2007 Published by under Pretty Pictures

In the tradition of "Friday Cat Blogging" (in which I will doubtlessly indulge at some point, what with being a nutty cat person), I intend to establish my own tradition of putting up some pretty picture or another of a galaxy each Friday. Today is barred spiral galaxy NGC 1365.


The spiral arms in this galaxy are apparent, as is the bar; this is one of the classic examples of a barred spiral galaxy. It was also the subject of a poster presented a month and a half ago at the AAS meeting in Seattle by my grad student, Katie Chynoweth. These images were taken by me with the 1.0m SMARTS telescope at Cerro-Tololo Inter-American Observatory (CTIO) in Chile. The color image combines images through a blue, green, and red filter, each of which had something like 1/2 hour of total integration time.

We're looking at NGC 1365 because it's a member of what's called the "Bright Galaxy Sample." That doesn't mean exactly what it sounds; it should really be called the "IRAS Bright Galaxy Sample," as it is a set of galaxies that are particularly bright in the infrared region of the spectrum; IRAS was an infrared satellite from a couple of deacdes ago. This galaxy is luminous enough in the infrared to qualify as a "LIRG" or "Luminous InfraRed Galaxy". These galaxies all have a huge amount of star formation. The star formation tends to be embedded in dense, dusty molecular clouds. The light from the star formation is partially trapped in the dust, heating it up; the dust radiates then in the infrared, making these galaxies LIRGs. This galaxy also has an active galacitc nucleus.

Fun times.

9 responses so far

  • Bill LaLonde says:

    Friday galaxy blogging-- very cool idea!
    I'm glad to see you on ScienceBlogs-- physical scientists have been pretty well outnumbered by life sciences folks. I love both, and it's nice to see the variety.

  • cephyn says:

    Gorgeous galaxy. Also looks like the international Hurricane weather symbol!

  • llewelly says:

    More accurately, the Hurricane weather symbol for the Southern hemisphere.
    The Coriolis force causes a hurricane's (tropical cyclone's) surface winds to spiral counter clockwise in the Northern hemisphere, and clockwise in the Southern hemisphere.
    Presently, it's the Southern hemisphere which is active.

  • The Ridger says:

    What a wonderful idea! I look forward to many gorgeous photos.

  • mollishka says:

    Excellent idea. I wanted to do a "galaxy of the week" thingie for a while, but then I started working on stars and ran out of steam. NGC1365 is definitely a nice one, but not nearly as cool as NGC1530 or as strongly barred as NGC1300.

  • Peter Erwin says:

    Oh, yes, very good idea. I approve. (And not just because of the fact that by the end of my thesis, I was in a state where I'd walk by offices with three- or four-digit numbers on the door and start involuntarily wondering if I knew which galaxy that was...)

  • raj says:

    Nice picture. You're on my daily reading list.
    Could you do an entry on today's NYTimes story at I haven't found anything on it over the Web. I'm am more interested in a more detailed description of the research methodology than was provided by the NYTimes. Links to journal papers would be sufficient if you don't want to do a whole blog entry.
    Thanks in advance.

  • mollishka says:

    raj: I believe there is a blogpost on this subject over at Uncertain Principles. Basically, by looking at the star in certain wavelengths (where water absorbs light) when the planet is in front of it and again when the planet is behind the star, you can look at the differences to deduce how much of the light is due to the planet. It's a reeeeeally hard measurement to make, but it looks like none of the planets that have been looked at this way show the kind of absorption that would be due to water in their atmospheres.

  • raj says:

    mollishka | February 24, 2007 10:09 PM
    Thanks for the information. It is the really hard measurement to make, considering that we are talking about light-year measurement of a molecule in a hay-stack over light years and such, that made me wonder about the article.
    I'll check out Uncertain Principles.