Astronomy Now Home
Home Magazine Sky Chart Resources Store

On Sale Now!



The April 2014 issue of Astronomy Now is on sale! Order direct from our store (free 1st class post & to UK addresses). The Astronomy Now iPad/iPhone editions are now available worldwide in the iTunes store.



Top Stories



Earthshine used to test life detection method
...By imagining the Earth as an exoplanet, scientists observing our planet's reflected light on the Moon with ESO's Very Large Telescope have demonstrated a way to detect life on other worlds...
  READ MORE

Solid buckyballs discovered in space
...Astronomers using NASA’s Spitzer Space Telescope have detected a particular type of molecule, given the nickname “buckyball”, in a solid form for the first time...
  READ MORE

Steamy water-world gets the Hubble treatment
...Hubble Space Telescope observations of a 7 Earth-mass planet find an unusual water-rich world swathed in a thick, steamy atmosphere...
  READ MORE








Hyperactive galaxies roam early Universe
DR EMILY BALDWIN
ASTRONOMY NOW

Posted: August 06, 2009


Bookmark and Share

Astronomers have measured the motions of stars for the first time in a very distant galaxy, speeding around its host at twice the speed of our Sun through the Milky Way.

The speeding stars may help astronomers understand how such compact galaxies form so early in the Universe and then evolve into the galaxies we see in today's 13.7 billion year old Universe.

This illustration compares the Milky Way with a compact galaxy in the early Universe. Image: NASA, ESA, and A. Feild (STScI).

"This galaxy is very small, but the stars are whizzing around as if they were in a giant galaxy that we would find closer to us and not so far back in time," says Pieter van Dokkum, professor of astronomy and physics at Yale University. The stars are clocking up speeds of over 1.6 million kilometres per hour.

Van Dokkum and colleagues used data from the Hubble Space Telescope to confirm the size of the galaxy, and the eight metre Gemini South telescope in Chile to collect enough light to determine the motions of the stars. These near-infrared spectroscopic observations of galaxy 1255-0 spanned 29 hours to allow the faint light to be collected.

"By looking at this galaxy we are able to look back in time and see what galaxies looked like in the distant past when the Universe was very young," says team member Mariska Kriek of Princeton University. Galaxy 1255-0 was born when the Universe was just three billion years old.

The team hope that the results will shed light on how such compact, massive galaxies form, and why they are not seen in today's local Universe. "One possibility is that we are looking at what will eventually be the dense central region of a very large galaxy," says Marijn Franx of Leiden University. "The centre of big galaxies may have formed first, presumably together with the giant black holes that we know exist in today's large galaxies that we see nearby."

The next step will be to capture these galaxies in the process of forming, such as with Hubble's new Wide Field Camera 3. "The ancestors of these extreme galaxies should have quite spectacular properties as they probably formed a huge amount of stars, in addition to a massive black hole, in a relatively short amount of time," says van Dokkum.

Recent work revealed that the oldest most luminous galaxies in the early Universe are also very compact, yet exhibit masses similar to those of today's elliptical galaxies. The most massive galaxies we see in the local Universe which have a mass similar to 1255-0 are typically five times larger than a young compact galaxy, so understanding how galaxies grew so much in the past 10 billion years is a key piece of evidence in eventually solving this puzzle.

The results of this study are presented in the August 6 issue of the journal Nature, along with a companion paper in the Astrophysical Journal.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 GET YOUR COPY

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 GET YOUR COPY

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 GET YOUR COPY


HOME | NEWS ARCHIVE | MAGAZINE | SOLAR SYSTEM | SKY CHART | RESOURCES | STORE | SPACEFLIGHT NOW

© 2014 Pole Star Publications Ltd.