Tag: astronomy

Detector Array Deterioration Poses New Problem for JWST

9:27 pm

More problems for the James Webb Space Telescope: The detector arrays for several instruments are deteriorating, even as they sit on the shelf. And remember, the 2014 launch date is probably going to be delayed until 2016. Key quote:

“As you get further and further out with [the launch date], it really raises questions about how far down the [integration and test] process you go for the instruments … and how long you have to store all that before you actually launch,” [Webb program director Rick Howard] told the NASA Advisory Council’s astrophysics subcommittee during a Feb. 16 public meeting here. “And that just makes everybody even more nervous about this problem than anything else.”

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More Webb budget troubles

10:56 am

According to its manager, the budget troubles of the James Webb Space Telescope will likely keep it on the ground until 2016.

This is terrible news for space-based astrophysics. Until Webb gets launched, NASA will have no money for any other space telescope project. And since all the space telescopes presently in orbit are not expected to be operating at the end of the decade, by 2020 the U.S. space astronomy program will essentially be dead.

Then again, there is the private sector, as Google Lunar X Prize is demonstrating.

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Stardust images of comet locate crater from Deep Impact’s impact

8:59 pm

More news from Stardust: scientists have now identified what they think is the crater produced by Deep Impact’s impact in 2005. Key quote:

The images revealed a 150-metre-wide crater at the Deep Impact collision point that was not present in 2005. The crater is a subtle feature in the images, but it appears consistently in multiple views from the spacecraft. “So I feel very confident that we did find the [impact] site,” said mission member Peter Schultz of Brown University in Providence, Rhode Island, at a press briefing on Tuesday. The crater’s features are “subdued” rather than sharply defined, like those of craters made in hard materials like rock. “The message is: This surface of the comet where we hit is very weak,” said Schultz. The crater also has a small mound in its middle, indicating that some of the material thrown up by the impact was drawn by the comet’s gravity back down into the crater, he said: “In a way, it partly buried itself.”

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Kepler finds 68 Earthsized planets

1:47 pm

Exoplanets galore! The Kepler team announced today the discovery of 68 Earth-sized planets, five in the habitable zone. Key quote:

The discoveries are part of several hundred new planet candidates identified in new Kepler mission science data, released on Tuesday, Feb. 1. The findings increase the number of planet candidates identified by Kepler to-date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are larger than Jupiter. Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable zone candidates range from super-Earth size — up to twice the size of Earth — to larger than Jupiter.

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A Fizzy Ocean on Enceladus

6:39 pm

A fizzy ocean on Enceladus? Key quote:

[Scientists believe] that gasses dissolved in water deep below the surface [of Enceladus] form bubbles. Since the density of the resulting “sparkling water” is less than that of the ice, the liquid ascends quickly up through the ice to the surface. “Most of the water spreads out sideways and ‘warms’ a thin surface ice lid, which is about 300 feet thick,” explains Matson. “But some of it collects in subsurface chambers, builds up pressure, and then blasts out through small holes in the ground, like soda spewing out of that can you opened.”

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The future Nemesis from space

3:01 pm

From the American Astronomical Society meeting this week:

A team of astronomers, using the data from the Sloan Digital Sky Survey, calculated the galactic orbits of nearly 40,000 low mass stars. These stars are generally M dwarfs, cool, not very bright, and thus generally somewhat close to the Sun since if they are too far away we would not see them. You can read the abstract here, and download their full poster here [pdf].

For the astronomers, the data told them a great deal about the orbital properties of these stars. Though a majority are in circular orbits between 20 to 30 thousand light years from the galactic center, a small minority are in extremely eccentric orbits that travel far out into the galactic halo, as much 260,000 light years. A few others dive inward, getting within 6000 light years of the galactic center.

What made this poster stand out to me, however, was this quote from the abstract:

In addition, we have identified a number of stars that will pass very close to the Sun within the next [billion years]. These stars form the “Nemesis” family of orbits. Potential encounters with these stars could have a significant impact on orbits of Oort Cloud and Kuiper Belt members as well as the planets. We comment on the probability of a catastrophic encounter within the next [billion years].

All told, they found that 18 low-mass cool M dwarf stars that will eventually pass close to the Sun. One star, SDSS J112612.07+152517.6, an M3 star that is about 2,300 light years away, is in an orbit that has it moving right towards us at about 90,000 miles per hour. Its mass is less than half that of the Sun, about 0.4 solar masses. This figure from the poster roughly illustrates the star’s position relative to our solar system over the next billion years:

Nemesis star

The star itself is shown in the inset. The red curve shows its calculated distance from the Sun over time, with the black area above and below showing the uncertainties of the calculation. As you can see, every hundred million years or so the distance between this star and the Sun shrinks, with the very very very rare possibility that the distance will sometimes shrink to zero!

With 18 stars each doing this every few 100 million years or so, the average time between close approaches is about 5 million years. These results suggest that another star passes close enough to our solar system frequently enough to not only disturb the comets in the Oort cloud, but also possibly affect the orbits of the planets in the outer solar system and Kuiper belt. One wonders, for example, if such an event had some influence on Pluto’s strange orbit.

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Giant black holes

6:39 pm

From the AAS meeting, the black hole press conference!

  • Scientists, using the Gemini telescope at Mauna Kea in Hawaii, have measured the mass of the supermassive black hole in the center of the galaxy M87, and found its mass equals 6.6 billion suns, far larger than expected. They also estimate that the event horizon of this gigantic black hole is so large our entire solar system would fit inside it.
  • Other scientists have found that the total mass of M87 is more than 5 trillion suns, about 60 percent higher than earlier investigations estimated. This makes M87 one of the most massive galaxies known. In addition, more than 80 percent of that mass is contained with the galaxy’s dark matter halo.
  • In other research, astronomers have located 16 close binary pairs of supermassive black holes hidden in the nuclei of the galaxies. Scientists have long believed that the merger of smaller orbiting supermassive black holes helps form bigger supermassive black holes we see, but until this discovery, almost no close binary pairs had been located. Of these 16 binaries, all show signs that they are spiraling into towards each other, and will crash together in several millions of years.
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