Astronomers image rare stellar cluster Liller 1

June 17, 2015 by Peter Michaud, Gemini Observatory
Gemini Observatory near-infrared image of the globular cluster Liller 1 obtained with the GeMS adaptive optics system on the Gemini South telescope in Chile. Credit: Gemini Observatory/AURA

Scientists have imaged a cluster of stars, heavily obscured by material in our galaxy, where stars are so densely packed that it is likely a rare environment where stars can collide. "It's a bit like a stellar billiards table; where the probability of collisions depends on the size of the table and on the number of billiard balls on it," said Francesco R. Ferraro of the University of Bologna (Italy), one of the team members who used the Gemini Observatory to make the observations.

The cluster of stars, known as Liller 1, is a difficult target to study due to its distance and also because it is located close to the center of the Milky Way (about 3,200 light-years away from it), where the obscuration by dust is very high. The unprecedented ultra-sharp view of the cluster reveals a vast city of stars estimated by the team to contain a total mass of at least 1.5 million suns, very similar to the most massive in our galaxy: Omega Centauri and Terzan 5.

"Although our galaxy has upwards of 200 billion stars, there is so much vacancy between stars that there are very few places where suns actually collide," said Douglas Geisler, Principal Investigator of the original observing proposal, from University of Concepcion (Chile). "The congested overcrowded central regions of globular clusters are one of these places. Our observations confirmed that, among globular clusters, Liller 1 is one of the best environments in our galaxy for stellar collisions."

Geisler's team specializes in the study of globular clusters near the center of the Milky Way, while Ferraro's team is adept at the reduction of infrared data on globular clusters. Both groups worked together to obtain the beautiful and detailed observations of Liller 1 with Gemini.

Liller 1 is a tight sphere of stars known as a globular cluster. Globular clusters orbit in a large halo around the center, or nucleus, of our galaxy and many of the closer globular clusters are spectacular showpieces, even in small telescopes or binoculars. "This isn't one of these showpieces, it is so obscured by material in the central bulge of our galaxy that is almost completely invisible in visual light," observed Sara Saracino, lead author on the paper, from the University of Bologna. Indeed, Liller 1 is located at almost 30,000 light years from Earth, in one of the most inaccessible regions of our galaxy, where thick clouds of dust prevent the optical light from emerging. "Only infrared radiation can travel across these clouds and bring us direct information on its stars," commented Emanuele Dalessandro of University of Bologna.

The observations of the tightly packed cluster used Gemini Observatory's powerful adaptive optics system at the Gemini South telescope in Chile.

A technical jewel named GeMS (derived from "Gemini Multi-conjugate adaptive optics System"), in combination with the powerful infrared camera Gemini South Adaptive Optics Imager (GSAOI), was able to penetrate the dense fog surrounding Liller 1 and to provide astronomers with this unprecedented view of its stars. This has been made possible thanks to the combination of two specific characteristics of GeMS: first, the capability of operating at near-infrared wavelengths (especially in the K pass-band); second, an innovative and revolutionary way to remove the distortions (blurriness) that the Earth's turbulent atmosphere inflicts on astronomical images. To compensate for the degradation effects of the Earth's atmosphere, the GeMS system uses three natural guide stars, a constellation of five laser guide stars, and multiple deformable mirrors. The correction is so fine that astronomers are provided with images of unprecedented sharpness. In the best K-band exposures of Liller 1, stellar images have an angular resolution of only 75 milliarcseconds, just slightly larger than the theoretical limit of Gemini's 8-meter mirror (known as the diffraction limit). This means that GeMS performed with almost perfect corrections of atmospheric distortions.

The international research team published the results in The Astrophysical Journal (article 152, volume 806, issue 2, June 15, 2015).

The observations for this project also included several other globular clusters. The results achieved on their first target, Liller 1, have been so important that they have increased their collaboration and are currently working on the other clusters which promise to deliver even more exciting science.

Background: Stellar collisions

Stellar collisions are important because they can provide the key to understand the origin of exotic objects that cannot be interpreted in terms of the passive evolution of single stars. Nearly head-on collisions in which the stars actually merge, mixing their nuclear fuel and re-stoking the fire of the nuclear fusion are suggested to be the origin of (at least part) of the so-called Blue Straggler Stars. But collisions can also involve binary systems, with the effect of shrinking the initial size of the system and thus promoting the two components to interact and producing a variety of objects like Low mass X-ray binaries, Millisecond pulsars etc. In particular Millisecond pulsars are old neutron stars reaccelerated to millisecond rotation period by mass accretion from a companion in a binary system. Indeed Liller 1 is suspected to have a large population of such exotic objects. Although no millisecond pulsar has been directly observed up to now, a large hidden population has been suggested because of the detection of an intense γ-ray emission (the most intense detected so far from a globular cluster). The Gemini observations indeed confirm that this is possible.

"Indeed our observations confirm Liller 1 as one of the best "laboratories" where the impact of star cluster dynamics on stellar evolution can be studied: it opens the window to a sort of stellar sociology study, aimed at measuring the impact of the reciprocal influence of when they are forced to live in conditions of extreme crowding and stress." concludes Ferraro.

Explore further: VLT discovers new kind of globular star cluster

More information: "GEMINI/GeMS observations Unveil the Structure of the Heavily Obscured Globular Cluster Liller 1," S. Saracino et al., 2015 June 15, Astrophysical Journal, Vol. 806, No. 2, Art. 152. DOI: 10.1088/0004-637X/806/2/152 . Arxiv: http://arxiv.org/abs/1505.00568

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billpress11
not rated yet Jun 17, 2015
What puzzles me is how stars in a cluster avoid being pulled by gravity toward the center. I have never read where the whole cluster is rotating. Red shift should easily be able to show this. Even if they were that would not explain how stars at the poles stay in apparently fixed positions over billions of years the age of these clusters.
Tuxford
1.3 / 5 (6) Jun 17, 2015
These objects are the likely locations of the intermediate black holes, hidden from view within the cores. And the cores producing substantial radiation pressure from new matter ejected therefrom, explains why there is not much angular momentum in the system, since it grows from the inside-out, rather than the reverse. And the radiation pressure can help bias the system to diverge, rather than converge, in many cases from near the center. Eventually, the cluster can grow to form the heart of a new satellite galaxy.
viko_mx
1 / 5 (4) Jun 18, 2015
Such globular clusters failed the idea that gravity is the main reason for formation of acretion discs or cosmic structures at all. Structure of vacuum of space? Like clock mechanism.
jsdarkdestruction
5 / 5 (4) Jun 20, 2015
Such globular clusters failed the idea that gravity is the main reason for formation of acretion discs or cosmic structures at all. Structure of vacuum of space? Like clock mechanism.

That's a pretty big claim you are making viko. Do you have specific evidence to back it up?
viko_mx
1 / 5 (4) Jun 20, 2015
To look but not to see. The evidence is before our eyes.
jsdarkdestruction
5 / 5 (4) Jun 20, 2015
You aren't very good at providing specific examples or evidence.
Tuxford
1 / 5 (6) Jun 20, 2015
No, the only matter "ejected" from a black hole is incoming matter that doesn't enter the hole, which usually produces jets, and Hawking radiation, which is minimal from a stellar mass of larger black hole.

There is likely to be a black hole in the core, produced from stellar collisions and mergers, but clusters don't grow from the black hole.


Just another mainstream cheerleader without a clue. You prefer math models leading to infinite densities and regions where physical (man-made) laws do not apply? Oh that is the way to religion! Keep the faith, despite the evidence.
RealityCheck
1.3 / 5 (6) Jun 21, 2015
Hi nkalanaga. :)

Yes. Mitchell's Dark Star didn't involve a 'singularity' object at center of relevant extreme/strong gravitational well, however that extreme/strong well formed.

This is the main bone of contention between those that say 'black holes don't exist' and those that claim 'GR says it does exist'.

In former, there's no 'tear in fabric of spacetime', merely a contiguous gradient in gravitational energy-space dynamics/processes which obtains even in the most extreme case locally; ie, there is NO 'hole' in 'spacetime', merely a region where light signals cannot return/emit from once within the point of no return.

Hence argument: the one being a DARK STAR (degenerate matter which has not collapsed to 'infinite density point', but is still an extended spacetime (energyspace) object within its event horizon); and the other being a GR extrapolation BH.

Whether whatever it is eventually explodes due to internal dynamics is unknown (except to my ToE, of course). :)
viko_mx
1 / 5 (4) Jun 21, 2015
"You aren't very good at providing specific examples or evidence. "

It is the same ike to look at the white color and you want to give you evidence that this color is white. If you do not want to see you will not seeing. Wide shut eyes.
Uncle Ira
3.4 / 5 (5) Jun 21, 2015
@ Really-Skippy. How you are Cher? I am doing not too bad my self, thanks for asking.

Whether whatever it is eventually explodes due to internal dynamics is unknown (except to my ToE, of course). :)


Sorry to hear about your toes are exploding. It that what is taking you so long with the REALLY-SKIPPY-ENCYCLOPEDIUM-ABOUT-TOES-AND-EVERYTHING-ELSE?

Oh yeah, I almost forget. What is causing them to explode? Maybe you should try some of the Gold-Bond-Foot-Powders stuffs.
RealityCheck
1 / 5 (5) Jun 21, 2015
Poor Idiot Uncle Ira.
Maybe you should try some of the Gold-Bond-Foot-Powders stuffs.
If that is what Ira is putting in his huff-n-puff wacky-pipe, no wonder he drivels and bot-votes on a science site, while sitting in his corner making and wearing his pointy hats. Explains a lot, hey folks?
Uncle Ira
3.9 / 5 (7) Jun 21, 2015
Poor Idiot Uncle Ira.
Maybe you should try some of the Gold-Bond-Foot-Powders stuffs.
no wonder he drivels and bot-votes on a science site, while sitting in his corner making and wearing his pointy hats. Explains a lot, hey folks?


Skippy, I am not the one who spends all day boohooing that nobody Really-Skippy-Realizes that I am the smartest homme that ever whined about the mod/gang/mafia/troll/bot/ever-what chasing me all about the interweb. And you are the one with the exploding toes and don't know what ever the reason is.

My toes is fine and dandy. And I don't have to pretend to be the scientist like I Really-Skippy-Am-Not. That is why I am fine and dandy so much of the time, and why you are grumpy and sad and frustrated and made fun with all the time. Life is too good and too short for all that foolishment you got going on with you.

RealityCheck
1 / 5 (5) Jun 21, 2015
One more try...

Ira, you have been bot-voting and trolling on a science site, in total uncomprehending state of the science being discussed from any 'side' in any discussion going into subtle but crucial aspects which mainstream science is not yet able to fully explain. If you stopped bot-voting and actually tried to follow the discussions you might learn something instead of just being a bot-voting trolling jerk on a science site.

You call it "boo-hooing" when someone is objectively observing the truth about something that has been proven to have been bringing the mainstream into disrepute in the science sites (by proven mod-troll gang outrageous sabotage and trolling and censoring and banning and lying campaigns against people in disregard of the science presented)?

Do you also call it "boo-hooing" when a child tells you about being sexually abused by those they trusted?

Wise up, Ira. Be a constructive participant in the discourse. Stop the bot-votes/trolls. :)
Uncle Ira
3.7 / 5 (6) Jun 22, 2015
You call it "boo-hooing" when someone is objectively observing the truth about something that has been proven


You got the mental condition Cher.

to have been bringing the mainstream into disrepute in the science sites


I don't think the mainstreams are much troubled by ol Ira-Skippy. They don't seem to be talking about me very much. You seem to be the only Skippy doing much talking about me and you are not what most peoples would call the mainstream.

(by proven mod-troll gang outrageous sabotage and trolling and censoring and banning and lying campaigns against people in disregard of the science presented)?


There goes that mental conditions again Cher.

Do you also call it "boo-hooing" when a child tells you about being sexually abused by those they trusted?


Cher, this is the comment page for amateurs on a interweb news place. I ain't said nothing about no sex stuffs.

RealityCheck
1 / 5 (5) Jun 22, 2015
You poor Ira. No wonder humanity is in trouble. Haven't you realized yet that EVERY forum and coffee shop and meeting place is important to the discourse in democracy and science? You're belittling this place is the very sort of thing the 'elitist' twats in religion and 'science' who censor and dismiss without fair hearing do whenever they ignore the evolving reality under their noses while sounding so certain that only 'they' have the ability to answer the questions. You are so devoid of self awareness and objective intellect that you wallow in your ignorance and try to bring everyone down to your level in your bot-voting troll pigpen. Do you not understand that I was proven correct all along? If you 'serve' science and scientists then you must also 'serve' the proven truth. If you deny the proven truth then you are just another drag on mankind and science. That is what you have been all along. You haven't learned. You won't learn. You can't learn. You only drivel.
RealityCheck
2 / 5 (4) Jun 22, 2015
Hi Ren82. :)

I think that cosmic vacuum is not emptiness but 3d physical structure with certain properties which defines the behavior of constituent particles of matter and their energetic interactions which are dissolved in this structure. Each point of this 3d structure can be addressed and reprogrammed by which can be modified behavior elementary particles in it or physical laws locally. There is two categories of physical laws. Fundamental and local. Fundamental laws are eternal and unchangeable. Local laws can be changed by the Creator.
Why did you have to bring your 'god' into it? You were doing so well until then, discussing scientific aspects which can be observed and deduced etc by objective means/intellect; and then you had to spoil it all by sending it into 'supernatural/religious' fantasyland 'context'. Why do you do it? The first bit was enough. No need for the second bit. Never has been. For humanity's sake, please resist the 'religion' compulsion. Thanks.
Uncle Ira
3.4 / 5 (5) Jun 22, 2015
@ Really-Skippy. How you are Cher? Well I can see how you are the same and still having the bad time. Moi? I am fine and dandy, thanks for asking.

Do you not understand that I was proven correct all along?


Non Cher. I do not understand that. Now that would bother me normally but not this time. Because that makes me just like everybody else in the world. If I was the only one who understood that you were proven correct all along, I would see about getting some treatments for the mental condition you have.

If you 'serve' science and scientists then you must also 'serve' the proven truth.


That's not a rock I would be chunking if I were you. And I am glad I am not you. You seem miserable all the time.

If you deny the proven truth then you are just another drag on mankind and science.


Another rock I would be leaving alone if I were you.

You haven't learned.


I've learned plenty, just not from you. But I have learned a lot about you.
RealityCheck
1 / 5 (5) Jun 22, 2015
You poor Ira. How much have you learned if you still BOT-vote and DRIVEL on a SCIENCE site? Nada. All you've 'learned' is how to troll and sabotage those who are discussing the science instead of the person/source. That's what you've learned from 'others', not from me. You would not be the only one to see I was proven correct all along. All the others who ALSO deny that reality see it too, but like you, they cannot admit I was correct and they wrong all along. That makes you and them hypocrites at best and anti-science dumkoffs at worst. Anything you have learned from such failures in objectivity and fairness is not worth the drivel you turn it into every time you bot-vote and troll on a science site. You are worse than god believers and climate science deniers. They don't know any better. But YOU, and the ones you've 'learned' from, profess to 'serve' mainstream science, scientists and truth....while all you've been doing is the OPPOSITE....and you don't even see it. Poor Ira.
Uncle Ira
3.4 / 5 (5) Jun 22, 2015
....and you don't even see it. Poor Ira.


@ Really-Skippy. You don't need to poor Ira me non. I have a good life. I have a really good family. I have a really good job and like him and am pretty sure that I'll have him for as long as I want. I got a pretty nice house and the land the land it sets on. (That picture of your house would make mine look like a palace.)

So Skippy, what I don't even see doesn't seem to be holding me back from anything I want to do. What you think I would want to go through life being like you? If you think that your mental condition is worse than anybody thought.

Oh yeah, I almost forget. There is one thing I would like to change but since it's something that Mrs-Ira-Skippette wants I am sort of stuck with it. We got her a new car a couple of weeks ago. All my neighbors are making fun with me about it. It's a Mini-Cooper and that is what she wanted. But it sure is embarrassing because sometimes I have to drive him and peoples laugh at me.
RealityCheck
1 / 5 (5) Jun 22, 2015
You poor pitiable Ira. You have everything except objective intellect and objective comprehension of the science being discussed. Just like a pig in muck, snuffling around for more crap while the whole point of human intellect and existence/aspiration regarding understanding the universe is beyond your reach intellectually. But you bot-vote and troll and drivel on a science site like a pig snuffling about the feet of your owners who will soon be cooking you. You've reached your 'terminal insensibility state', you poor pitiable driveling 'happy as a pig in muck' Ira.
TehDog
5 / 5 (4) Jun 22, 2015
Hey Ira, UK folks laugh at them too, they are not this;
http://www.wallpa...s-996301
Drove a mini once, wrecked the gearbox in under 50 miles, rough roads :)
Captain Stumpy
5 / 5 (4) Jun 23, 2015
UK folks laugh at them too,
Drove a mini once, wrecked the gearbox in under 50 miles, rough roads :)
LOL

@TehDog
@Ira

we used to turn them sideways in their parking spots when we found them on base... or if we were partying and ran across one!
they are a lot of fun to drive through the mountains on curvy roads though... but a serious hassle when you have more than one other person with you and you need to get to work!
LOLOL
Fundamental laws are eternal and unchangeable. Local laws can be changed by the Creator.
@renTROLL
this directly refutes your claims of an omniscient and omnipotent deity
it also means your deity could not have performed the "miracles" as stated in the bible as there were fundamental laws broken in most cases (like cellular senescence or fusion without heat or light)

perhaps you would like to rethink your comment?
like i said... as it stands, it directly violates your previous claims as well as biblical ones, etc

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