Brightest galaxy

[Dragan]

Here's a question.....

Last night during an observing session, good friend and DSF member Darren Drake posed a good question to the group. After some discussion, consensus seemed to point towards M32 but noone could say with certainty.

What galaxy has the brightest square arc-second of surface area?

Whats your guess?

(And no, we don't have the correct answer. It was just a question he asked)

[Clear Skies]

I will go with LMC. Then I got curious and found this (http://reference.wolfram.com/legacy/applications/astronomer/Atlas/BrightestGalaxies.html) with a quick Google search.

[Dragan]

That list refers to an objects apparent magnitude. Darren is interested in finding out which galaxy has the brightest surface area per square arc-second.

For example, the core of M32 has an apparent brighter surface area per square arc-second than say the core of M33, even though M33's apparent magnitude is brighter than M32's. (5.7 for M33 vs 8.0 for M32)

I forwarded him my post. I hope he will reply soon with clarification. After all, it was his original query.

[Howard B]

The Milky Way galaxy of course, but for an external galaxy I'd vote for M31.

[Jim Chandler]

Here's a question.....

Last night during an observing session, good friend and DSF member Darren Drake posed a good question to the group. After some discussion, consensus seemed to point towards M32 but noone could say with certainty.

What galaxy has the brightest square arc-second of surface area?

Whats your guess?

(And no, we don't have the correct answer. It was just a question he asked)

For maximum surface brightness, I would think maybe one of the Markarian galaxies. Some of them have SB numbers in the 17-18 range.

Jim

[Astrojensen]

The Milky Way galaxy of course, but for an external galaxy I'd vote for M31.

We're not talking about total magnitude, but surface brightness. Tremendous difference here.

[Astrojensen]

What galaxy has the brightest square arc-second of surface area?

NGC 4486A, a companion to M87, comes to mind. The SB per square arc minute is around 10.3 or something. It's extremely small and compact and looks like a star at anything below 150x. It is very easily visible in my 60mm's, but look completely stellar. I accidentally discovered its nonstellar nature by accident with a C8 at 400x.


Clear skies!
Thomas, Denmark

[Astrojensen]

In the grey companion book to U2000.0, NGC 4486A are listed as having a SB of 11.3 and a total mag of 11.6, while NGC 4486B is listed as 10.3 and 13.3, respectively. That is clearly an error, as NGC 4486A has a MUCH higher visual SB than 4486B, not just a larger total brightness. This is also visible in many photos. The core of NGC 4486A is as easy to see as that of M87.

Maybe the SB of NGC 4486A in the grey book takes a larger, fainter outer area of the galaxy into account than what can be seen visually.


Clear skies!
Thomas, Denmark

[JayinUtah]

Well, I would assume we are talking visually since Herschel and Hubble have imaged in various wave lengths galaxies that are extremely bright. I sorted the Saguaro Astronomy Club database, and sorted by Surface Brightness and type being galaxy. Here is what I got. The brightest galaxy by Surface Brightness is Maffei 1, an elliptical in Cassiopeia. Next is NGC 2288, then NGC 742 and NGC 573 followed by NGC 543.

Some other findings:

Here is the 200 Brightest Galaxies by Blue Magnitude. They are at Link 1 (http://www.palmbeachastro.org/galaxies.htm) and at Link 2 (http://www.atlasoftheuniverse.com/galax200.html).

An interesting powerpoint on Ellipticals and it covers their surface brightness (I would assume and that is dangerous )that an elliptical would be the brightest galaxy with the highest surface brightness Link to PDF (http://www.astro.rug.nl/~ahelmi/galaxies_course/class_VII-E/ellip-06.pdf).

Third Reference Catalog to Bright Galaxies at this Link (http://heasarc.nasa.gov/W3Browse/all/rc3.html). Not sure how much help the link is.

For fun, and perhaps it should be its own threat here is a listing of the brightest Nebula on the Palm Beach Astro page. Link (http://www.palmbeachastro.org/nebulae.htm)

Also the visual detection calculator might come in handy here. Link (http://www.bbastrodesigns.com/VisualDetectionCalculator.htm).

[Darren Drake]

What I am looking for is which galaxy has the brightest 1 square arcsecond of all galaxies. One square arcsecond only. Not average high suface brighness. Big difference....

[Astrojensen]

The brightest galaxy by Surface Brightness is Maffei 1, an elliptical in Cassiopeia

Wut? That one is faint and dim visually. Even the core is hard to detect in a small telescope.


Clear skies!
Thomas, Denmark

[Astrojensen]

What I am looking for is which galaxy has the brightest 1 square arcsecond of all galaxies. One square arcsecond only. Not average high suface brighness. Big difference....

Do you want figures only for the core, which is extremely hard to find? Are we talking only visually visible galaxies? Do you consider extremely faint, small objects with intrinsically very high surface brightness or does the targets need to be bright visually? Some Messier or NGC galaxies have very tiny, stellar cores with high SB, but overall, the SB is average or dim, the SB of the core is not listed in commonly available lists.

It would probably be easy to find a mag 18 object with an intrinsically very high SB, but it would not be a very impressive object visually... Not even in a 48"...:o


Clear skies!
Thomas, Denmark

[Darren Drake]

Right it may not be realistic to answer this question with any certainty but it would be interesting to hear people's opinions on which galaxy they think seems to have the brightest core region as seen visually. Only considering the innermost one square arcsecond or so limits big core region galaxies from having an advantage over more distant galaxies that might still have a very bright stellar type nucleus. My vote that I would choose if I had to would be M32. The core is simply amazingly bright when examining the only the core. I am interested in hearing others opinions on if they think they know of a galaxy that might have a brighter 1 square arcsecond region than M32.

[Howard B]

I'm still thinking M31 because the core is very bright.

[Don Pensack]

Yes, if you take average surface brightness above the mag.25 isophote, M32 isn't anywhere in the running for brightness, at mag.12.2
The brightest is actually IC3881 with mag.9.2 and there are a ton of small MCG galaxies with average surface brightnesses in the mag.9-10 range.
They're very small, and some of them concentrate all their lights into areas smaller than a minute, so surface brightnesses are misleading.
The RC3 of Vaucouleurs has a column that gives average surface brightness of the brightest 50% of a lot of galaxies and lists NGC6125 as the brightest at magnitude 9.2.
I can't find any reference that describes the magnitude of just the brightest one square arc-minute, though. It might not even be a bright galaxy, since you are looking only for a steep brightness gradient with a high peak.
I've observed galaxies for 50 years, and quite a few have a bright stellar nucleus. These would seem to be brighter in the central arc-minute than those without a bright nucleus. M32 probably wasn't a bad guess.

[Darren Drake]

Don
I was only thinking of a square arc second not minute which is obviously a somewhat different story. Put another way however many trillions of square arc seconds there are in the whole celestial sphere which one is occupied by the highest surface brightness due to a galaxy. It may not be possible to answer which is why its fun here to at least have some guesses
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