Archive for March, 2013

The most distance object: MACS0647-JD

In November 2012, a new distance record breaker has been weighed in with a photometric redshift of  z ~ 10.8 which is roughtly 420 million years after the big bang. This is pretty significant.

The Cluster Lensing and Supernova survey with Hubble (CLASH), and the Spitzer/IRAC has measured the photometric redshift and with the help of Gravitational Lensing has been able to see the object by it’s increased visability and determined its distance.

The paper on the object, together with 2 other distance candidates, can be viewed (in full if you have access) on ApJ: http://iopscience.iop.org/0004-637X/762/1/32 or you can get a pre-print on ArXiv which is almost the same as the ApJ paper: http://arxiv.org/pdf/1211.3663v1.pdf

MACS0647-JD is the one of the three with the largest redshift, and a Lyman Break Galaxy. The light from the relic galaxy, at the time of transmission, was so small and may have been in the first stages of forming a larger galaxy.

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Comet PANSTARRS

Comet PANSTARRS

Comet PANSTARRS

* Comet PANSTARRS (C/2011 L4) in Cetus * Photo By Humayun Qureshi. Taken from Canberra.

Astronomers discovered Comet PANSTARRS (C/2011 L4) on June 7, 2011. In early February, the comet reached its southernmost point, but by the end of May it will lie near Polaris (Alpha [α] Ursae Minoris).

Comet watchers should target February 21 through March 27, when the Comet PANSTARRS should shine more brightly than a 2nd-magnitude star (like Polaris). On March 5, the 1st-magnitude comet lies closest to Earth. Search for it after sunset 17° southeast of the Sun. Use binoculars or a rich-field telescope.

Hubble Finds the Oldest Star (as of March 2013)

This is a Digitized Sky Survey image of the oldest star with a well-determined age in our galaxy. The aging star, cataloged as HD 140283, lies 190.1 light-years away. The Anglo-Australian Observatory (AAO) UK Schmidt telescope photographed the star in blue light. Credit: Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech, and UKSTU/AAO

A team of astronomers using NASA’s Hubble Space Telescope has taken an important step closer to finding the birth certificate of a star that’s been around for a very long time.

“We have found that this is the oldest known star with a well-determined age,” said Howard Bond of Pennsylvania State University in University Park, Pa., and the Space Telescope Science Institute in Baltimore, Md.

The star could be as old as 14.5 billion years (plus or minus 0.8 billion years), which at first glance would make it older than the universe’s calculated age of about 13.8 billion years, an obvious dilemma. This is going to be a strom in the cosmology world, as most believe that the univsere 13.7 gigayears (billion years) old – admittedly its only an estimate, but one that will be pushed back.

But earlier estimates from observations dating back to 2000 placed the star as old as 16 billion years. And this age range presented a potential dilemma for cosmologists. “Maybe the cosmology is wrong, stellar physics is wrong, or the star’s distance is wrong,” Bond said. “So we set out to refine the distance.”

The new Hubble age estimates reduce the range of measurement uncertainty, so that the star’s age overlaps with the universe’s age — as independently determined by the rate of expansion of space, an analysis of the microwave background from the big bang, and measurements of radioactive decay.

http://www.nasa.gov/mission_pages/hubble/science/hd140283.html