Where to find life in the Milky Way galaxy

A paper published today on the Los Alamos astro-ph preprint website has attempted to model the habitable zones within the Milky Way galaxy. From the abstract:

We predict that ~1.2% of all stars host a planet that may have been capable of supporting complex life at some point in the history of the Galaxy. Of those stars with a habitable planet, ~75% of planets are predicted to be in a tidally locked configuration with their host star. The majority of these planets that may support complex life are found towards the inner Galaxy, distributed within, and significantly above and below, the Galactic midplane.[emphasis mine]

They took into consideration the hazard of supernovae for killing off planetary life, as well as other factors such as the where the necessary heavier elements would be available for producing planets.

You can download the paper here [pdf].

A new image of Vesta from Dawn

Dawn continues to approach the large asteroid Vesta. Below is an image taken July 1st from about 62,000 miles. The image has a resolution of 5.8 miles per pixel.

Despite Vesta’s large size, 330 miles in diameter, it is nonspherical. This fact, combined with data that says it is differentiated with a core and mantle, suggests that it is the remains of a larger object that subsequently broke up.

Vesta from 62,000 miles

The most distant quasar ever found

Astronomers have found the most distant quasar ever, and are baffled by its existence.

The light from the quasar started its journey toward us when the universe was only 6% of its present age, a mere 770 million years after the Big Bang, at a redshift of about 7.1 [3]. “This gives astronomers a headache,” says lead author Daniel Mortlock, from Imperial College London. “It’s difficult to understand how a black hole a billion times more massive than the Sun can have grown so early in the history of the universe. It’s like rolling a snowball down the hill and suddenly you find that it’s 20 feet across!”

Cassini directly samples the plumes from Enceladus and finds an ocean-like Spray

Cassini has directly sampled the plumes from Enceladus and discovered a salty ocean-like spray.

The new paper analyzes three Enceladus flybys in 2008 and 2009 with the same instrument, focusing on the composition of freshly ejected plume grains. The icy particles hit the detector target at speeds between 15,000 and 39,000 mph (23,000 and 63,000 kilometers per hour), vaporizing instantly. Electrical fields inside the cosmic dust analyzer separated the various constituents of the impact cloud.

The data suggest a layer of water between the moon’s rocky core and its icy mantle, possibly as deep as about 50 miles (80 kilometers) beneath the surface. As this water washes against the rocks, it dissolves salt compounds and rises through fractures in the overlying ice to form reserves nearer the surface. If the outermost layer cracks open, the decrease in pressure from these reserves to space causes a plume to shoot out. Roughly 400 pounds (200 kilograms) of water vapor is lost every second in the plumes, with smaller amounts being lost as ice grains. The team calculates the water reserves must have large evaporating surfaces, or they would freeze easily and stop the plumes.

Hadrian built his country estate with the buildings aligned with the sun

The Roman emperor Hadrian built his country estate with the buildings aligned with the sun.

For centuries, scholars have thought that the more than 30 buildings at Hadrian’s palatial country estate were oriented more or less randomly. But De Franceschini says that during the summer solstice, blades of light pierce two of the villa’s buildings.

In one, the Roccabruna, light from the summer solstice enters through a wedge-shaped slot above the door and illuminates a niche on the opposite side of the interior (see image). And in a temple of the Accademia building, De Franceschini has found that sunlight passes through a series of doors during both the winter and summer solstices.

An X-ray deep field over six weeks by Chandra finds massive black holes common in early universe

An X-ray deep field image taken over a six week period by Chandra had found that massive black holes are common in early universe.

These results imply that between 30% and 100% of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the relatively small field of view that was observed to the full sky, there are at least 30 million supermassive black holes in the early Universe. This is a factor of 10,000 larger than the estimated number of quasars in the early Universe.

The progenitor of the May supernova in M51 identified

supernova 2011dh before it exploded

The progenitor star that produced the May supernovae in the Whirlpool Galaxy (also known as M51) has been identified, and it isn’t what scientists predicted.

In a preprint paper published today on the Los Alamos astro-ph website, astronomers describe the star that exploded as a yellow supergiant, not a red supergiant or Wolf-Rayet star, as predicted by the theory explaining this particular type of supernova. Moreover, though theory also favors the star being a member of a binary system, the progenitor of 2011dh appears to be a lone star, not even a member of a cluster.
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A press conference of my very own

This week the Space Telescope Science Institute in Baltimore, Maryland was holding a conference on the future research possibilities of the James Webb Space Telescope, and ended the conference with a writer’s workshop/press conference today.

Not surprisingly, there was not a lot of press interest. The Webb telescope is way behind schedule and over budget, and is not scheduled for launch until 2018. For most of the press, a press conference now on what Webb might someday do is really nothing more than a NASA sales pitch. Most reporters, including myself, don’t find these kinds of press conferences of much worth.

However, after thinking about it a bit, I decided to go, with the hope that I might be able to find out some more details about the state of the telescope’s construction.

To my astonishment, I discovered how little press interest there was, as it turned out I was the only journalist there! When the presentations ended, the whole workshop became an exercise in answering Bob Zimmerman’s questions about Webb and astronomy. I felt a bit embarrassed about this, but then decided the only stupid question is the one you don’t ask, and forged ahead. Moreover, the situation probably was far more embarrassing for the press people at the Institute then it was for me.
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