New galaxy discovered

[Robert9]

Reported in today's "Age", 27/3/09, p3. A dwarf galaxy named SUCDI . It was formed not long after the "Big Bang" sitting in the Sombrero galaxy. Discovered by five astronomers from Swinbourne Uni and three Americans in Hawaii. At 33,000 ly its the closest to Earth, and could be up to 10billion years old.
Robert

[Baddad]

Such articles in the Melb Age is good to see. Here in Brisbane they hardly ever print good stuff. Its mosty gossip articles or rugby.

I may try and locate a newsagent that carries the Age. Thanks for the info.
I certainly want to read about a new galaxy discovery.

[Robert9]

Sorry to hear about the Brisbane news drought. "The Age" isn't bad on such stuff, but also have front page news of the latest football goss. :zzz2:
Just an additional snippet - they report the discovery was made using the world's largest optical telescope, the 10 metre Keck II in Hawaii.

[MikeyB]

Somewhere in a tiny galaxy not so far away (http://www.brisbanetimes.com.au/national/somewhere-in-a-tiny-galaxy-not-so-far-away-20090326-9cdd.html)

[Jen]

:D thats cool :thumbsup:

[Quark]

This is a link to the full story which is in the current edition of The Swinburne Magazine supplement which was in The Australian 25th March 2009.
http://www.swinburne.edu.au/magazine/

Regards
Trevor

[Baddad]

Thanks Trevor.:)
You are one of the examples that makes IIS what it is. I wanted info and you showed me how.:thumbsup: I already checked for the Age at the local newsagent. No Go. But now I've read the story in comfort.

[ngcles]

Hi Trevor & All,



Thanks for posting the link to Swinburne Magazine. The short article in the Fairfax press posted earlier (and it's not MikeyB's fault) was so "boiled-down" that I had almost no idea what it was reporting.

First (in par 2) it says the new object is "in isolation", then later (par 4) said it was within M104. :doh: What par 4 is trying to say, is, well, hard to say.:shrug:The whole short article is very confusing. No wonder lay-people sometimes find astronomy so incomprehensible.

The Swinburne Magazine article, despite being written for a "scientific publication" and a scientific audience explains the new finding simply (in a way that can be comprehended by most people) but equally, fully. Yes, I know it's longer and I know there is only limited space in newspapers (even broadsheets) but ...

Thanks for clearing up my confusion Trevor!


Best,

Les D

[leinad]

Gotta love google ;)

http://arxiv.org/PS_cache/arxiv/pdf/0901/0901.1693v1.pdf

[Quark]

Hi Les,

There is still a problem, even with the Swin Mag article. Obviously it was not proof read by Duncan, or for that matter any of his team.

In the article the distance to SUCD1 is said to be similar to M 104, the distance is then given as 33,000 light years, obviously wrong and in need of another three zero's or 10 mega parsecs, obviously correct.

If you look at the published paper via the link in the previous post in this thread you will see the recessional velocity given for SUCD1 is 1293.1 +- 9.5 km/s. The recessional velocity for M 104 is 1024 +- 5 km/s, this gives a relative velocity for SUDC1 to M 104 of 269 +- 11 km/s.

Obviously from this data SUDC1 is not within M 104 but externally associated with it. There is also a couple of images in the original paper, of M 104 with SUCD1 highlighted to show its position relative to M 104.

Regards
Trevor

[gregbradley]

Can I ask a question?

How could a galaxy near to us possibly be dated not long after the "Big Bang".

That would mean that our galaxy would have to be near the centre of the physical universe and I doubt that is the case given the 300 billion or so galaxies estimated to exist.

Also it would assume scientists have identified the centre of the physical universe and I do not know that anybody has.

Greg.

[ngcles]

Hi Trevor,



I'm inclined to agree Trevor. Leinad posted the link to the original paper on arxiv.org and I took a look at that last night, well after my previous post about how bad the Fairfax snippet was compared to the Swinburne article. The upshot is, the Swinburne article got a few things wrong too. Further they haven't accurately encapsulated the tentative conclusion Duncan and the others have arrived at.

They find it difficult to conclude the origin of this object or even to classify it. It is very peculiar and (without re-reading the paper again and going on memory) (feel free to correct me -- anyone. That way we all learn which is the object of the exercise) very compact object for its mass, probably in excess of 12gyr old (comparable to the globulars) has a composite spectrum about G-class (like many globulars) yet is from its half-light radius and overall brightness much, much bigger than any GC seen before. Its metallicity is very high or even extremely high for a GC -- comparable or even exceeding the most metal rich globulars. If it is a globular, where did all the metals come from?

The absolute magnitude is put at approx -12.3 -- comparable with many dwarf galaxies and somewhat higher than what is expected of even the brightest globulars. For comparison, that's about 2.3 magnitudes or 8-odd times brighter than the Milky Way's big-boys and even much brighter than say Mayall II (the most massive Andromeda GC). So it does not fit easily into the globular cluster bucket on that count either, but its position in relation to M104 well-out in the halo seems to fit well with being a GC and not a dwarf. It is a fairly bright (comparitively) X-ray emitter too whcih seems to fit with it being a GC. A great many if not nearly all the high mass globulars (eg 47 Tuc, NGC 2808, M15) are X-ray emitters for one reason or another.

So, it's size brightness etc is more consistent with it being a dwarf as is the metalicity. But ... there is no evidence of tidal tails -- which is what you'd expect if it were a tidally stripped dwarf -- even several Gyr down the track there would be a trail of stars and stuff trailing behind and preceding it in its orbit. So if it is the remnant core or a stripped dwarf, there's precious little evidence of it unless it happened a very, very long time ago. M104 seems to be a field galaxy -- almost alone in its surroundings. If this new object is a stripped dwarf, where did it come from? Dwarfs are rare if not unknown outside of populous galaxy clusters. If it's a dwarf, there is also little or no evidence of dark-matter which is also abnormal (though not unknown). If it is a dwarf, it is also the first to be detected in X-rays (very unusual).

So at present it fits rather badly in either category (G.C or tidally-stripped dwarf). Could it be a "missing-link" or a trasitional object between the two in an evolutionary chain? The paper talks of past simulations that ultimately produce things that look like and act like Omega Centauri out of a captured and stripped dwarf (Omega may be a stripped dwarf) but apparently nothing as big as this thing comes easily out of the simulations.

The way I read it, in the end they lean toward it being an exceptional, extremely massive metal-rich "super-globular" (my term-- not their's) that formed in association with M104 and isn't a captured dwarf, but it's a looooong way from certain.

One thing is for certain, this will be a highly-studied object over the next while and it looks fascinating.

I'd encourage anyone to have a read of the original paper -- for this sort of paper it's easy going (well-written) and most if not all people here will be able to digest the gist of it. Even if you read just the abstract and the conclusion, I think you'll learn a lot.

Thanks also to leinad for posting the link to the original paper. Thanks again to Robert for drawing everyone's attention to the report.

BTW, any of our ultra-deep imagers out there prepared to have a go at capturing this thing with an amateur 'scope ?? It is visible in the Sky-map.org image and even in the old POSS faintly. There are several stars near it about 17th/18th magnitude and it looks 18th magnitude--ish. Small but not too hard you'd think to image.


Best,

Les D

[ngcles]

Hi Greg & All,



Sorry I posted a reply to Trevor and appeared to ignore you for a while, but I'm had to go to work and I'm back home now and ...

Without writing a whole essay (as I usually do)(I know, I know) as I understand it, there is no real 'centre' to the physical universe as such.

Virtually the big galaxies that are reasonably nearby (say within 100 million ly) to the Milky Way are approximately the same age which is not a lot younger than the age of the Universe at about 14Gyr. The dwarfs have varying ages, some very old, some old and a few young ones. They are dated from their spectra which reveal the age of their oldest stars. They can't be younger that the oldest stars in them!

The Globular Clusters are some of the oldest, if not the oldest stellar associations in the Universe. They may have been one placewhere the fabled (theorised but not yet found) Population III stars (that no longer exist) once lived. The GC's are (by definition) all 10Gyr old or older. Some are up to 13Gyr old.

Hope this is some help.


Best,

Les D

[astroron]

http://arxiv.org/PS_cache/arxiv/pdf/...901.1693v1.pdf
Reply With Quote
Trevor, I have just read the paper and the article in the Swinburne magazine, and they have very little resemblance to each other.
As you say there must have been no proof reading of the article even at the Swinburne end.

[Quark]

Hi Ron,

Julian Cribb is an excellent journalist, I have personal experience with him. He was commissioned by Swinburne to write an article on me that was published in the same issue of the Swinburne Magazine.

Regarding the article on Duncan's research team's discovery, there really can be no comparison between the paper submitted to a professional journal by a research team at the pointy end of their field and an article by a journalist for public consumption.

Recall that the Swinburne Magazine is published as a supplement in The Australian, so is targeted at a more general readership.

It is probably a good thing that, inadvertently, it included some errors as due to that, all of us and probably many others have read the original paper.

Regards
Trevor

[astroron]

Hi Ron,

Julian Cribb is an excellent journalist, I have personal experience with him. He was commissioned by Swinburne to write an article on me that was published in the same issue of the Swinburne Magazine.

Hi Trevor, I read and enjoyed the article, and thought a well presented piece on you.
Well done.

[Paddy]

Thanks for the discussion all - very interesting. It is fantastic in particular to have Les' insights and questions. Will definitely have a go at the article and thanks to Daniel for posting the link.