Tiny Galaxy Observed 420 Million Years After the Big Bang

MACS 0647-JD
Hubble Image of Very Young Dwarf Galaxy MACS0647-JD
Image Credit: NASA / ESA / M. Postman / D. Coe (STScI) / CLASH Team.

NASA has released an image of a newly discovered galaxy that is the youngest object seen so far. The young dwarf galaxy, named MACS0647-JD, is only 600 light-years across and is seen only 420 million years after the Big Bang (13.3 Billion light-years away from Earth).

The galaxy is tiny. For comparison, the Large Magellanic Cloud, a dwarf galaxy companion to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across.

The image above is a composite taken with Hubble’s Wide Field Camera 3 (WFC 3) and the Advanced Camera for Surveys ( ACS) on 5 October and 29 November 2011. The work was done by the Cluster Lensing And Supernova Survey with Hubble (CLASH) team.

More Planets than Stars – But Axial Tilt is the Key to Life

Planets
There is an average of more than one planet per star in the Milky Way
Image Credit: NASA / ESA / ESO

With the forthcoming publication in the journal Nature on 12 January, it is estimated that there are more than 100 billion planets in our Milky Way galaxy. That means more than one planet per star, and results show that there are more rocky small Earth-like planets than giant Jupiter-size gas planets.

Most recent discoveries have come from the Kepler Observatory using transit observations. Some of the earliest confirmation of gas giants came from radial velocity Doppler observations.

The conclusions in the Nature article are based on micro-lensing studies.

Recent results from the Kepler Observatory have shown the existence of three small, rocky planets around the star KOI-961, a red dwarf. These three planets, named KOI-961.01, KOI-961.02 and KOI-961.03, are 0.78, 0.73 and 0.57 times the radius of Earth. The smallest is about the size of Mars (see below). Follow-up observations were made by the Palomar Observatory, near San Diego, and the Keck Observatory atop Mauna Kea in Hawaii.

KOI-961
Relative size of the three rocky planets around KOI-961
Image Credit: NASA / JPL-Caltech

Since it is now clear that rocky planets exist around millions, if not billions, of stars, the question arises as to whether there is life on them, and whether it may resemble life on Earth.

Whether a planet exists in the “Goldilocks” region around a star depends on many factors. Three factors include the type of star, how far away from the star the planet resides and the atmospheric pressure of the planet. A red dwarf, such as Gliese 581, means the planet has to be closer than the Earth to our Sun. A white hot star means the planet has to be farther away. And if the atmosphere is low, like Mars, or to high, like Venus, liquid water is not likely.

A fourth factor is axial tilt. If a planet has no axial tilt (the spin axis is perpendicular to the plane of its orbit around the star) then the polar regions freeze and the equatorial regions bake. There is little exchange between these regions due to atmospheric circulation. Axial tilt, such as the Earth has, allows distribution of heat between the equator and the poles.

Even if a planet has axial tilt, a recent study shows that interaction at a close distance (within the “Goldilocks” region) with red dwarf will eliminate axial tilt in less than 100 million years. Bacteria on Earth required 1,000 million years to evolve. Theoretically, a planet with no axial tilt could possess bands between the equator and the poles where liquid water would exist. But, it is quite possible the atmosphere would collapse, with gases being driven off into space at the very hot equator, and freezing solid on the ground at the poles. Such a possibility faces the planets around KOI 961.

Systems with stars like our Sun present better possibilities. The “Goldilocks” conditions exist much farther out, and axial tilt is eliminated much more slowly, as our Earth is witness. Systems such as Kepler-22b are good candidates.

The conclusion drawn from these studies is that systems similar to our Solar System present the best opportunities for life.

Black Hole in the Milky Way Galaxy Set to Devour Gas Cloud


Video Credit: ESO / MPE / M. Schartmann / L. Calçada

A cloud of gas is being pulled closer to the supermassive black hole lurking in the center of our galaxy, 27,000 light-years away. This unprecedented discovery is being monitored by an international team of scientists using the European Southern Observatory’s Very Large Telescope (VLT). The cool cloud, composed mainly of hydrogen and helium, with a mass three-times that of Earth, has been picking up speed, and by 2013, astronomers will hopefully see some fireworks. By then, the first wisps of gas should be sucked into the black hole’s event horizon causing the black hole to flare brightly.

WISE Images – Galaxy IC342

IC 342
Galaxy IC 342
Image Credit: NASA/JPL-Caltech/WISE Team

Known as the Hidden Galaxy, IC 342 is mostly hidden to astronomers in the visible spectrum by the Milky Way. However, the WISE observatory can see through the dust and gas with its infrared vision giving scientists a sharp view of the galaxy. IC 342 is very bright due to the formation of new stars. The Hidden Galaxy is 62,000 light years across, compared to 100,000 light years for the Milky Way. It is about 10 million light years from Earth.