Tag: astronomy

Dark matter disappears

9:15 am

The uncertainty of science: A new study has found no evidence of dark matter within 13,000 light years of the Sun, something that had not been expected.

According to widely accepted theories, the solar neighborhood was expected to be filled with dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts. But a new study by a team of astronomers in Chile has found that these theories just do not fit the observational facts. This may mean that attempts to directly detect dark matter particles on Earth are unlikely to be successful.

These findings will be as controversial as the now abandoned faster-than-light neutrino results last fall. Here, however, the new data is likely going to be more robust, which will cause the entire astrophysical community some real conniptions.
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Astronomers have identified two of the oldest known stars, about 12 billion years old, both only a hundred light years away.

4:19 pm

Astronomers have identified two of the oldest known stars, about 12 billion years old, both only a hundred light years away.

What is intriguing about this discovery is that these two white dwarfs had to have formed very soon after the Big Bang, long before the Milky Way galaxy existed as we know it today. How they ended up here is an interesting puzzle.

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The Giant Magellan Telescope project has decided it will not participate in a funding competition offered by the National Science Foundation.

8:49 am

The 24.5 meter Giant Magellan Telescope project (GMT) has decided it is not interested in competing for funds offered by the National Science Foundation (NSF).

With just US$1.25 million available to the winner, the NSF competition was less about money and more about prestige. The NSF has been adamant that it has no significant money to support either project until the early part of next decade. But the Thirty Meter Telescope, which will still respond to the NSF’s solicitation, believed that a competition would at least demonstrate the NSF’s intention to eventually support one project — and that the winner would have an easier time attracting international partners.

But the GMT says it can go it alone, at least for now. On 23 March, the group began blasting at its mountaintop site in Chile. And they say they are nearly halfway towards raising the $700 million they need to complete construction.

If the GMT has already raised almost $350 million without NSF support, it makes perfect sense for them to thumb their noses at this piddling funding from the NSF, especially since the bureaucratic cost of getting that money will probably be far more than $1.25 million.

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NASA management yesterday extended funding for almost all of its on-going astrophysics missions, including Hubble, Kepler, Chandra, and Fermi.

8:37 am

NASA management yesterday extended funding for all but one of its on-going astrophysics missions, including Hubble, Kepler, Chandra, and Fermi.

According to a statement from NASA headquarters, all missions will continue in fiscal years 2013 and 2014. The guest observer programme for the Chandra X-ray Observatory would even be augmented. Only Spitzer, an infrared telescope, would be phased out earlier than the mission wanted, in 2015.

There is some justification for ending Spitzer’s funding early, as the spacecraft’s cameras have lost their ability to stay as cold as designed to do their full range of infrared observations.

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If there is water ice on the Moon, scientists have found that the bombardment from interstellar cosmic rays has likely caused chemical reactions that “can create complex carbon chains similar to those that help form the foundations of biological structures.”

9:11 am

Life stranger than science fiction: If there is water ice on the Moon, scientists have found that the bombardment from interstellar cosmic rays has likely caused chemical reactions that “can create complex carbon chains similar to those that help form the foundations of biological structures.”

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The orbit of a 150 foot wide asteroid that zipped past the Earth in February, has an orbit so much like the Earth’s that astronomer’s expect it back next year.

7:42 pm

Duck! The orbit of a 150 foot wide asteroid that zipped past the Earth in February, has an orbit that will bring it past the Earth again on February 15, 2013 by less than 15,000 miles.

The team use several automated telescopes to scan the sky, and the discovery came somewhat serendipitously after they decided to search areas of the sky where asteroids are not usually seen. “A preliminary orbit calculation shows that 2012 DA14 has a very Earth-like orbit with a period of 366.24 days, just one more day than our terrestrial year, and it ‘jumps’ inside and outside of the path of Earth two times per year,” says Jaime.

While an impact with Earth has been ruled out on the asteroid’s next visit, astronomers will use that close approach for more studies and calculate the Earth and Moon’s gravitational effects on it.

Because this newly discovered asteroid passes so close and frequently to both the Earth and Moon, astronomers will need a lot more data before they can pin down its orbit precisely, and thus predict the chances of a collision in the near future.

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The blistering hot exoplanet where it snows

4:13 pm

The blistering hot exoplanet where it snows.

These results have led to a suggestion that [HD 189733b] could continually experience silicate snow. In the lower atmosphere of [the exoplanet], magnesium silicate sublimates, that is, it passes directly from a solid into a gas. But we know there are small silicate particulates in the upper atmosphere. Formation of these particulates requires that the temperature be lowered, and so must have been formed at a temperature inversion in the atmosphere. The generally windy conditions would help some of the tiny particulates grow into respectable snow crystals.

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smaller planets are preferentially found in low-eccentricity orbits.

9:24 am

More Kepler results: From the abstract of a preprint paper published today on the Los Alamos astro-ph website:

The mean eccentricity of the Kepler candidates decreases with decreasing planet size indicating that smaller planets are preferentially found in low-eccentricity orbits.

In other words, the smaller a planet is, the more likely its orbit will be circular like the Earth’s. This result is encouraging news for the search for life on other worlds. Before Kepler, astronomers had found that the orbits of most exoplanets were far more eccentric than the orbits of the planets in our solar system, a condition that scientists thought was unfriendly for the development of life. These new results counter that conclusion. The orbits of the planets in our solar system might not be as unusual as first thought.

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JPL has issued a press release “reality check” on the impact possibilities of asteroid 2011 AG5 in 2040.

9:37 am

JPL has issued a press release “reality check” on the impact possibilities of asteroid 2011 AG5 in 2040.

“In September 2013, we have the opportunity to make additional observations of 2011 AG5 when it comes within 91 million miles (147 million kilometers) of Earth,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “It will be an opportunity to observe this space rock and further refine its orbit. Because of the extreme rarity of an impact by a near-Earth asteroid of this size, I fully expect we will be able to significantly reduce or rule out entirely any impact probability for the foreseeable future.” Even better observations will be possible in late 2015.

In other words, we really will not know anything more about these possibilities until late next year.

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A supernova twenty-five years later.

9:29 am

A supernova twenty-five years later.

SN 1987A, it turns out, was like a dust-bomb, with estimates of the total dust it threw into space, based on the infrared brightness of the dust … implying enough dusty material to build the equivalent of 200,000 Earth-mass planets. Mingled within the dust are elements as diverse as oxygen, nitrogen, sulphur, silicon, carbon and iron. This immense amount of dust has been beyond expectations and, if all supernovae spew out this much dust, it helps explain why young galaxies that we can see existing in the early Universe, which have high rates or star birth and death, are so dusty. The dust, however, isn’t a nuisance to be wiped away – this is the material that goes into building new planets, moons and even life. The iron in your blood and the calcium in your bones all came from supernovae like SN 1987A, as mostly did the oxygen we breath and the carbon in our constituent molecules.

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Mapping the surface of an extrasolar planet light years away.

8:05 am

Mapping the surface of an extrasolar planet light years away. From the paper’s abstract [pdf]:

We use archived Spitzer [Space Telescope] data of [the star] HD189733 … encompassing six transits, eight secondary eclipses, and a phase curve in a two-step analysis. The first step derives the planet-star system parameters. The second step investigates the structure found in eclipse scanning, using the previous planet-star system parameter derivation as Gaussian priors.

We find a 5-sigma deviation from the expected occultation ingress/egress shape for a uniform brightness disk, and demonstrate that this is dominated by large-scale brightness structure and not an occultation timing offset due to a non-zero eccentricity. Our analysis yields a 2D brightness temperature distribution showing a large-scale asymmetric hot spot whose finer structure is limited by the data quality and planet orbit geometry. [emphasis mine]

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