Nav: Home

The GTC obtains the deepest image of a galaxy from Earth

June 09, 2016

Observing very distant objects in the universe is a challenge because the light which reaches us is extremely faint. Something similar occurs with objects which are not so distant but have very low surface brightness. Measuring this brightness is difficult due to the low contrast with the sky background. Recently a study led by the Instituto de Astrofísica de Canarias (IAC) set out to test the limit of observation which can be reached using the largest optical-infrared telescope in the world: the Gran Telescopio CANARIAS (GTC). The observers managed to obtain an image 10 times deeper than any other obtained from the ground, observing a faint halo of stars around the galaxy UGC0180, which is 500 million light years away from us. With this measurement, recently published in the specialized journal Astrophysical Journal the existence of the stellar halos predicted by theoretical models is confirmed, and it has become possible to study low surface brightness phenomena.

The currently accepted model for galaxy formation predicts that there are many stars in their outer zones, which form a stellar halo, and is the result of the destruction of other minor galaxies. The problem about this is that these halos consist of very few stars in a very large volume. For example in the Milky Way the fraction of stars in its halo is about 1% of the total number of stars in the galaxy, but distributed within a large volume, several times bigger than the rest of the Galaxy. This means that the surface brightness of galaxy halos is extremely low, and only a few of them have been studied even in nearby galaxies. Because of this difficulty the scientists had questioned the possibility of observing further away and obtaining ultra-deep images, even though technological development has provided us with bigger and bigger telescopes capable of exploring the surface brightness of fainter and fainter galaxies.

For their recent experiment the observers used the GTC, which is at the Roque de los Muchachos Observatory in Garafía, (La Palma, Canary Islands). They chose the galaxy UGC00180, which is quite similar to our neighbour, the Andromeda Galaxy, and to other galaxies to which they have references, and they used the OSIRIS camera on the GTC, which has a field big enough to cover a decent area of sky around the galaxy, in order to explore its possible halo. After 8.1 hours of exposure they could show that it does have a weak halo composed of four thousand million stars, about the same number as those in the Magellanic Clouds, which are satellite galaxies of the Milky Way.

As well as beating the previous surface brightness limit by a factor of ten, this observation shows that it will be possible to explore the universe not only to the same depth to which we can go using the conventional technique of star counts, but also out to distances where this cannot be achieved, (UGC00180 is 200 times further away than Andromeda). Another advantage is that this new technique can be used to explore other faint structures in the sky, whether they contain stars or not. "After showing that the technique works" says Ignacio Trujillo, a researcher at the IAC and the first author of the study, " the object of future research is to extend the study to other types of galaxies, to see whether this way of understanding their formation, predicted by the standard model, is correct or not".
-end-


Instituto de Astrofísica de Canarias (IAC)

Related Stars Articles:

On the origin of massive stars
This scene of stellar creation, captured by the NASA/ESA Hubble Space Telescope, sits near the outskirts of the famous Tarantula Nebula.
And then there was light: looking for the first stars in the Universe
Astronomers are closing in on a signal that has been travelling across the Universe for 12 billion years, bringing them nearer to understanding the life and death of the very earliest stars.
Massive stars grow same way as light stars, just bigger
Astronomers obtained the first detailed face-on view of a gaseous disk feeding the growth of a massive baby star.
Our history in the stars
Astronomers map the substance aluminum monoxide (AlO) in a cloud around a distant young star -- Origin Source I.
Stars exploding as supernovae lose their mass to companion stars during their lives
Stars over eight times more massive than the sun end their lives in supernovae explosions.
Old stars live longer than we thought
The type of stars we refer to, which cannot be seen by the naked eye, officially up to now the objects which have suffered the greatest loss of mass.
A nearby river of stars
Astronomy & Astrophysics publishes the work of researchers from the University of Vienna, who have found a river of stars, a stellar stream in astronomical parlance, covering most of the southern sky.
Merging neutron stars
The option to measure the gravitational waves of two merging neutron stars has offered the chance to answer some of the fundamental questions about the structure of matter.
Bubbles of brand new stars
This dazzling region of newly forming stars in the Large Magellanic Cloud (LMC) was captured by the Multi Unit Spectroscopic Explorer instrument (MUSE) on ESO's Very Large Telescope.
Stars shrouded in iron dust
The Instituto de Astrofísica de Canarias (IAC) has participated in a study which has discovered a group of stars very poor in metals and shrouded in a high fraction of iron dust, situated in the Large Magellanic Cloud.
More Stars News and Stars Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.