Tag: astronomy

Astronomers have discovered that the nearest star to the Earth, Alpha Centauri, has an exoplanet only slightly heavier than the Earth.

3:28 pm

Big news: Astronomers have discovered that the nearest star to the Earth, Alpha Centauri, has an exoplanet only slightly heavier than the Earth.

Alpha Centauri is actually a triple star system, with two sunlike stars in a tight orbit around each other and a third star far out orbiting them both. The exoplanet orbits one of the inner stars every 3.2 days.

More details from Nature here.

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A super Earth, made of diamonds

8:55 am

A super Earth, made of diamonds.

Astronomers also thought 55 Cancri e contained a substantial amount of super-heated water, based on the assumption that its chemical makeup was similar to Earth’s, Madhusudhan said. But the new research suggests the planet has no water at all, and appears to be composed primarily of carbon (as graphite and diamond), iron, silicon carbide, and, possibly, some silicates. The study estimates that at least a third of the planet’s mass — the equivalent of about three Earth masses — could be diamond. “By contrast, Earth’s interior is rich in oxygen, but extremely poor in carbon — less than a part in thousand by mass,” says co-author and Yale geophysicist Kanani Lee.

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A star has gone supernova and astronomers get to see it from the very beginning, and even earlier!

7:05 pm

A star has gone supernova and astronomers get to see it from the very beginning, and even earlier!

The star had erupted several times before but had not produced a real supernova explosion. On September 26 it finally did so. Moreover, astronomers have images of the star prior to any eruption, information that until recently was not available for any supernovae.

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Astronomers have discovered a star that circles the supermassive black hole at the center of the Milky Way in only 11.5 years.

5:57 pm

Dizzy: Astronomers have discovered a star that circles the supermassive black hole at the center of the Milky Way in only 11.5 years.

This newly discovered star joins another that is 15 times brighter and has a 16 year orbit. The combined orbital data from both will allow astronomers to measure precisely the size of the black hole while also measuring the distortion of space caused by its intense gravitational field.

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Using data from the Spitzer Space Telescope astronomers have narrowed the universe’s rate of expansion to about 74.3 kilometers per second per megaparsec.

11:22 am

The uncertainty of science: Using data from the Spitzer Space Telescope astronomers have narrowed the universe’s rate of expansion to about 74.3 kilometers per second per megaparsec.

The importance of this number, also called the Hubble Constant, is that it allows astronomers to extrapolate more precisely backward to when they believe the Big Bang occurred, about 13.7 billion years ago. It also is a crucial data point in their effort to understand dark energy, in which this expansion rate is actually accelerating on vast scales.

Back in 1995 a team led by Wendy Freedman, the same scientist leading the work above, announced that they had used the Hubble Space Telescope to determine the expansion rate as 80 kilometers per second per megaparsec. Then, the margin of error was plus or minus 17 kilometers. Now the margin of error has been narrowed to plus or minus 2.1 kilometers.

Do I believe these new numbers? No, not really. Science has nothing to do with belief. I do think this is good science, however, and that this new estimate of the Hubble constant is probably the best yet. I would also not be surprised if in the future new data eventually proves this estimate wrong.

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The solar maximum has already occurred in the Sun’s northern hemisphere, according to new observations.

9:16 am

The solar maximum has already occurred in the Sun’s northern hemisphere, according to one scientist’s research.

Moreover, the data also suggests that the maximum in the Sun’s southern hemisphere will not occur until early in 2014. This asymmetry between the hemispheres also suggests the strong possibility of a Grand Minimum to follow.

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The next great comet?

10:19 pm

Amateur astronomer Jason Lewis sent me an email today describing how the amateur astronomy community is abuzz with the discovery of a new comet, presently dubbed C/2012 S1, that is due to make its dive around the Sun in late November 2013 and pass closest to the Earth in January 2014 at a distance of about 37 million miles. Based on the preliminary numbers, this comet might be one of the brightest in years, almost certainly a naked eye object and visible to everyone from both the northern and southern hemispheres.

To quote the comments from one astronomy forum:
» Read more

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Astronomers using the Chandra X-Ray Observatory have found that the Milky Way is surrounded by a halo of hot gas.The uncertainty of science: Astronomers using the Chandra X-Ray Observatory have found that the Milky Way is surrounded by a halo of hot gas.

12:04 pm

The uncertainty of science: Astronomers using the Chandra X-Ray Observatory have found that the Milky Way is surrounded by a halo of hot gas.

This is the key quote:

The estimated mass of the halo is comparable to the mass of all the stars in the galaxy. If the size and mass of this gas halo is confirmed, it also could be an explanation for what is known as the “missing baryon” problem for the galaxy.

“Missing baryon” is another way to say “dark matter.” In other words, this discovery might prove that it isn’t necessary to invent exotic unknown particles of physics, such as the Weakly Interacting Massive Particles (WIMPs) to explain the missing matter. The missing matter might simply be this hot gas, previously undetected.

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Astronomers have measured the most powerful magnetic field ever found around a star.

9:02 am

Astronomers have measured the most powerful magnetic field ever found around a star.

The star’s magnetic field is 20,000 times stronger than the Sun’s, and almost 10 times stronger than that detected around any other high-mass star. At about 35 times the Sun’s mass, the O-type star NGC 1624-2 lies in the open star cluster NGC 1624, about 20,000 light-years away in the constellation Perseus.

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Another planet has been found in the habitable zone

9:06 am

Planets without end: Another planet has been found in the habitable zone.

Gliese 163c could have a size between 1.8 to 2.4 Earth radii, depending if it is composed mostly of rock or water, respectively. It receives on average 40% more light from its parent star than Earth from the Sun, making it hotter. In comparison, Venus receives 90% more light from the Sun than Earth. We do not know the properties of the atmosphere of Gliese 163c but, if we assume that it is a scaled up version of Earth’s atmosphere, then its surface temperature might be around 60°C [140°F]. Most complex life on Earth (plants, animals, and even humans) are not able to survive at temperatures above 50°C [122°F], however, plenty of extremophilic microbial life forms can thrive at those temperatures or higher.

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New Horizons — on its way to Pluto — will take a look at a different Kuiper Belt object in January 2015.

2:46 pm

New Horizons — on its way to Pluto — will take a look at a different Kuiper Belt object in January 2015.

The encounter will take place at a range of about 75 million km, a distance somewhat subject to change depending on how the probe makes its course correction. At such a great distance, New Horizons will not be able to discern features on the surface of the KBO, nor will it be able to make spectroscopic observations to try to determine the composition of the surface material.

However, New Horizons will be in an excellent position to look for small, close-in moons around the object. It will also be in a position to observe the object’s phase curve, which is a measure of how the reflectivity of the surface changes as a function of viewing angle. This will reveal a great deal about the fluffiness of the surface material (note – fluffiness is a technical term meaning, roughly, “the opposite of dense”). These two observations cannot be made from Earth, even with the most powerful telescopes available.

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