Tag: astronomy

Astronomers think they have discovered a distant supermassive black hole that is being ejected from its galaxy at a speed of several million miles per hour.

4:48 pm

Astronomers think they have discovered a distant supermassive black hole that is being ejected from its galaxy at a speed of several million miles per hour.

Although the ejection of a supermassive black hole from a galaxy by recoil because more gravitational waves are being emitted in one direction than another is likely to be rare, it nevertheless could mean that there are many giant black holes roaming undetected out in the vast spaces between galaxies. “These black holes would be invisible to us,” said co-author Laura Blecha, also of CfA, “because they have consumed all of the gas surrounding them after being thrown out of their home galaxy.”

This conclusion however is not final. The data could also be explained by the spiraling in of two supermassive black holes.

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The military has given NASA two Cold War era spy space telescopes with mirrors comparable to Hubble’s.

2:40 pm

Big news: The military has given NASA two Cold War era spy space telescopes with mirrors comparable to Hubble’s.

They have 2.4-meter (7.9 feet) mirrors, just like the Hubble. They also have an additional feature that the civilian space telescopes lack: A maneuverable secondary mirror that makes it possible to obtain more focused images. These telescopes will have 100 times the field of view of the Hubble, according to David Spergel, a Princeton astrophysicist and co-chair of the National Academies advisory panel on astronomy and astrophysics.

Since astronomers have over the past dozen years been remarkably uninterested in launching a replacement for Hubble, they now find themselves in a situation where they might have no optical capabilities at all in space. Hubble is slowing dying from age, and NASA doesn’t have the money to build a new optical space telescope, especially since with any new space telescope proposal the astronomical community has had the annoying habit of demanding more sophistication than NASA can afford.

This announcement however might just save astronomy from becoming blind. Because these spy telescopes are already half built, it will be difficult to add too many bells and whistles. Hire a launch rocket, build the cameras and spectrographs based on the instruments already on Hubble, and get the things in orbit quickly.

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A failed public works project — from the year 1350 AD

4:02 pm

Casa Grande

Yesterday my wife Diane and I took my 94-year-old mother on a sightseeing trip to see the Casa Grande ruins southeast of Phoenix, “the largest known structure left of the Ancestral People of the Sonoran Desert.”

This four story high structure was built around 1350 AD from bricks made of concrete-like caliche mud, with the floors and roofs supported by beams of pine, fir, and juniper brought from as far away as fifty miles. (The rooflike structure above the ruins was built by the National Park Service in order to protect it from rain.)

Though impressive, I must admit I’ve seen far more impressive American Indian ruins elsewhere. Casa Grande, which means “Great House” in Spanish, suffered as a tourist attraction from two faults:
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The first solar eclipse to cross the continental United States in two decades will occur on May 20.

7:09 pm

Set your calendar: The first solar eclipse to cross the continental United States in two decades will occur on May 20.

An annular solar eclipse occurs when the moon passes between the earth and sun, but the lunar disk does not completely block out the sun and instead leaves a “ring of fire” visible around the moon at the point of maximum eclipse. Most anyone west of the Mississippi will see a partial eclipse, but the real treat will be for those located in the 200-mile wide path of the eclipse which will trek east from the California / Oregon border through Nevada, Utah, Arizona, New Mexico, and finally set below the horizon in west Texas.

Remember, you will need good eye protection if you choose to look.

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One astronomer has found that the habitable zone around some smaller stars is smaller than first calculated because of tidal heating.

9:45 am

One astronomer has found that the inner edge of the habitable zone around some dwarf stars is smaller than first calculated because tidal forces overheat planets close to the star.

Then again, this heating might expand the habitable zone in other directions. Stars might overheat when close to the star, but get a boost of needed heat when they would normally be too far away.

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Astronomers now believe that Type 1a supernovae — used to discover dark energy — can be produced in two different ways.

9:52 am

The uncertainty of science: Astronomers now believe that Type 1a supernovae — used to discover dark energy — can be produced in two different ways.

Type Ia supernovae are known to originate from white dwarfs – the dense cores of dead stars. White dwarfs are also called degenerate stars because they’re supported by quantum degeneracy pressure. In the single-degenerate model for a supernova, a white dwarf gathers material from a companion star until it reaches a tipping point where a runaway nuclear reaction begins and the star explodes. In the double-degenerate model, two white dwarfs merge and explode. Single-degenerate systems should have gas from the companion star around the supernova, while the double-degenerate systems will lack that gas.

For astronomers, this possibility raises several conflicting questions. If two different causes produce Type 1a supernovae, could their measurement of dark energy be suspect? And if not, why is it that these two different causes produce supernovae explosions that look so much alike?

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Scientists have discovered that the half life of one of their key isotopes for dating the solar system is 30% shorter than previously believed.

6:38 pm

The uncertainty of science: Scientists have discovered that the half life of one of their key isotopes for dating the age of the solar system is 30% shorter than previously believed.

The main result of the work of the international scientists, detailed in a recent article in Science, is a new determination of the half-life of 146Sm, previously adopted as 103 million years, to a much shorter value of 68 million years. The shorter half-life value, like a clock ticking faster, has the effect of shrinking the assessed chronology of events in the early solar system and in planetary differentiation into a shorter time span.

The new time scale, interestingly, is now consistent with a recent and precise dating made on a lunar rock and is in better agreement with the dating obtained with other chronometers. The measurement of the half-life of 146Sm, performed over several years by the collaborators, involved the use of the ATLAS particle accelerator at Argonne National Laboratory in Illinois.

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The Department of Energy has approved the start of detailed engineering for the Large Synoptic Survey Telescope.

5:36 pm

Ground-based astronomy moves forward: The Department of Energy has approved the start of detailed engineering for the camera on the Large Synoptic Survey Telescope.

I have to admit, I am puzzled why the Department of Energy is involved in this. Government funding for ground-based telescopes normally comes from the National Science Foundation.

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Europe has decided to build a probe, dubbed JUICE, to study Ganymede, Callisto and Europa, Jupiter’s big icy moons.

5:31 pm

Europe has decided to build a probe to study Ganymede, Callisto and Europa, Jupiter’s big icy moons.

Known as JUICE, the Jupiter Icy Moons Explorer, the probe will enter orbit around the gas giant planet in 2030 for a series of flybys of Ganymede, Callisto and Europa. JUICE will brake into orbit around Ganymede, Jupiter’s largest moon, in 2032 for at least one year of close-up research.

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More problems for Dark Matter

9:29 am

Vast Polar Structure

A new study by astronomers has found a vast structure of satellite galaxies and star clusters aligned perpendicular to the Milky Way and extending outward above and below the galaxy’s nucleus by as much as a million light years.

In their effort to understand exactly what surrounds our Galaxy, the scientists used a range of sources from twentieth century photographic plates to images from the robotic telescope of the Sloan Deep Sky Survey. Using all these data they assembled a picture that includes bright ‘classical’ satellite galaxies, more recently detected fainter satellites and the younger globular clusters.

“Once we had completed our analysis, a new picture of our cosmic neighbourhood emerged”, says Pawlowski. The astronomers found that all the different objects are distributed in a plane at right angles to the galactic disk. The newly-discovered structure is huge, extending from as close as 33,000 light years to as far away as one million light years from the centre of the Galaxy.

An animation illustrating this galactic distribution is posted below the fold. You can read the actual preprint paper here.

The problem with this polar alignment with the Milky Way’s core is that the theories for explaining the distribution of dark matter do not predict it.
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New data from a neutrino telescope in Antarctica had found that cosmic rays don’t come from gamma ray bursts, as had been believed by astronomers.

9:43 pm

The uncertainty of science: New data from a neutrino telescope in Antarctica has found that cosmic rays don’t come from gamma ray bursts, as had been believed by astronomers. You can read the paper here. [pdf]

Which means that astronomers at this moment have no idea what produces these high energy cosmic rays.

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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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