Author Topic: The Hanny's Voorwerp.  (Read 119737 times)

Edd

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Re: What's the blue stuff below?
« Reply #30 on: August 23, 2007, 01:19:22 pm »
The blue blob is nearer +34 43 34 than +34 43 58 dec. An explorer page for it.
When I look up at the night sky and think about the billions of stars out there, I think to myself: I'm amazing. - Peter Serafinowicz

Alice

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Re: What's the blue stuff below?
« Reply #31 on: August 23, 2007, 02:11:50 pm »
Well, Hanny, you're famous.  :) (And it's great to have you back online.)

Hanny

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Re: What's the blue stuff below?
« Reply #32 on: August 23, 2007, 02:14:59 pm »
Well, Hanny, you're famous.  :) (And it's great to have you back online.)

Thanks Alice, it's great to be back! And I love reading what Kevin and Edd had to say about "my ubs" :D

zookeeperKevin

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Re: What's the blue stuff below?
« Reply #33 on: August 23, 2007, 02:18:39 pm »
The blue blob is nearer +34 43 34 than +34 43 58 dec. An explorer page for it.

Ah duh. NED sneakly re-centered on the big galaxy, which now clearly is the radio source.

The blue blob remains mysterious.

mitch.wheat

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Re: What's the blue stuff below?
« Reply #34 on: August 26, 2007, 03:26:52 am »
I happened to be browsing the hubble site (unrelated to this topic) and came across this

http://hubblesite.org/gallery/album/galaxy_collection/pr2004019d/

Could a black hole be responsible for the 'blue-blob'. I'm assuming it would show up in other parts of the spectrum?

Edd

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Re: What's the blue stuff below?
« Reply #35 on: August 26, 2007, 09:15:34 am »
It's a confusing image, but the blue blobs there are purely the Chandra X-ray telescope images overlaid, there's no blob in the optical like we're seeing here.
When I look up at the night sky and think about the billions of stars out there, I think to myself: I'm amazing. - Peter Serafinowicz

Hanny

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Re: What's the blue stuff below?
« Reply #36 on: December 04, 2007, 05:34:36 am »
I found it back! (the topic) ;D

Fluffy pm'ed me (thanks ;)) about this article:
http://www.newscientist.com/blog/space/

So, is it Santa?

NGC3314

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Re: What's the blue stuff below?
« Reply #37 on: December 04, 2007, 12:51:09 pm »
Thanks guys, I really don't know what you're talking about (Edd)  ;)
SDSS sees in five colours (u,g,r,i and z) and computer monitors only do red, green and blue. The usual images make g blue, r green and i blue, but I switched some round to see the u and z instead, making u blue, i green and z red. The weird thing about this object is that the detection was pretty much only in the g band, rendered blue in your original image, but I thought there might be more hints in the others - and I think you can see a faint blue triangle there.

So I suspect it's real, but I don't really have a good idea what it actually is.

I might be biased by another project I'm trying to finish - but you might consider a Lyman alpha blob in some structure at redshift 3 or so (lemme see - peak response of SDSS g is something like 4860 Angstroms, that would catch Ly-alpha around z=3.0, where a whole bunch of these blobs turn up in other fields.) Examples: here and (pardon) here. They may have AGN in the middle, substantial galaxies, submillimeter galaxies, or no obvious central continuum object at all. We can now show that these very large ionized gas clouds are specifically a high-redshift phenomenon (and thus there presence is connected to early phases of galaxy evolution), since GALEX doesn't turn up any by the time we get to z=0.8.

Hanny

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Re: What's the blue stuff below?
« Reply #38 on: December 05, 2007, 08:35:49 am »
Aha, I guess that means no, not Santa ;D thanks for your post ;)

zookeeperKevin

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Re: What's the blue stuff below?
« Reply #39 on: December 05, 2007, 02:38:21 pm »
We need to keep this object in mind. It's weird and I'd like to know what it is.

Alice

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Re: What's the blue stuff below?
« Reply #40 on: December 05, 2007, 08:43:07 pm »
I don't think anyone's even posted the picture yet . . . it's very weird.


zookeeperKevin

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Re: What's the blue stuff below?
« Reply #41 on: December 05, 2007, 09:03:54 pm »
I'd love to get a spectrum of it because right now we have no idea whether it's in our backyard or half-way across the universe.

Stegra

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NGC3314

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Re: What's the blue stuff below?
« Reply #43 on: December 06, 2007, 05:35:35 pm »
To get this on the record so we (I) don't lose it - more details relevant to followup and figuring out what this is.

I grabbed the SDSS FITS files for the GZ "blue blob" and measured some magnitudes for the blob and what looks like a point source at its northern end. These are ordinary (pure log) magnitudes, with zero point from a bluish star just to the south.
filter  total   ptsrc/adopted error
u      20.46    23.36 0.3
g      18.29    20.48 0.2
r       22.49    21.49 0.1
i       20.02    20.86 0.2
z     >19.0     21.83 0.3

There is something there in the uri bands, but much of that is from the small source at the north tip; it's basically not there at all in the z band. The g band is so much brighter that it almost has to be from some strong emission line showing up in that filter.

Also, one can use the energy zero points (I took the ones from Fukugita et al.) to see how much flux would be coming out if the g band magnitude is all in one emission line near the peak of the filter transmission (circa 4800 A). That looks to be about 2.5e-16 erg/cm^2 s spread over about 12x17 arcseconds. Surprisingly, this leaves a Lyman-alpha blob in the running as an explanation - the brightest ones in SSA22 measured by Matsuda et al. (2004 AJ 128, 569) have fluxes up to 7e-16. So this may indeed be one of these rare denizens of the early Universe (I note that there are zookeepers who are properly skeptical - somebody's gotta get a spectrum).

The blob is much more structured and well-detected than I would have thought from the color composite. I'm attaching a  comparison of guriz images with statistically comparable linear displays, along with these numbers so I don't lose them again.

EricFDiaz

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Re: What's the blue stuff below?
« Reply #44 on: December 06, 2007, 07:40:02 pm »
I've read all the comments to the original post, as well as the two papers to which Dr. Keel was kind enough to provide links. I have to say that I agree with Kevin and Dr. Keel that someone has to get a spectrum of this object. I've never seen anything like this before. And, I'm dying to know what the heck it is.