Astronomers discover new exoplanet similar in size to Earth; Planet Kepler-21b found using space and ground-based observations

ScienceDaily (Nov. 30, 2011) — The NASA Kepler Mission is designed to survey a portion of our region of the Milky Way Galaxy to discover Earth-size planets in or near the "habitable zone," the region in a planetary system where liquid water can exist, and determine how many of the billions of stars in our galaxy have such planets. It now has another planet to add to its growing list.

A research team led by Steve Howell, of NASA's Ames Research Center, has shown that one of the brightest stars in the Kepler star field has a planet with a radius only 1.6 that of Earth's radius and a mass no greater that 10 Earth masses, circling its parent star with a 2.8-day period. With such a short period, and such a bright star, the team of over 65 astronomers -- which included David Silva, Ken Mighell and Mark Everett of the National Optical Astronomy Observatory (NOAO) -- needed multiple telescopes on the ground to support and confirm their Kepler observations. These included the 4-meter Mayall telescope and the WIYN telescope at Kitt Peak National Observatory.

With a period of only 2.8 days, this planet, designated Kepler-21b, is only about 6 million kilometers away from its parent star. By comparison Mercury, the closest planet to the sun, has a period of 88 days and a distance from the sun almost ten times greater, or 57 million km. So Kepler 21b is far hotter than any place humans could venture. The team calculates that the temperature at the surface of the planet is about 1900 K, or 2960 F. While this temperature is nowhere near the habitable zone in which liquid water might be found, the planet's size is approaching that of Earth.

The parent star, HD 179070, is quite similar to our sun: its mass is 1.3 solar masses, its radius is 1.9 solar radii, and its age, based on stellar models, is 2.84 billion years (or a bit younger than the sun's 4.6 billion years). HD 179070 is spectral type F6 IV, a little hotter and brighter than the sun. By astronomical standards, HD 179070 is fairly close, at a distance from the sun of 352 light years. While it cannot be seen by the unaided eye, a small telescope can easily pick it out.

Part of the difficulty in detecting this planet is the realization, from the Kepler mission, that many stars show short period brightness oscillations. The effect of these must be removed from the stellar light in order to uncover the regular, but very small, dimming caused by the planet passing in front of the star. The Kepler mission observed this field for over 15 months, and the team combined the observations to enable them to detect this tiny, periodic signal. They also relied on spectroscopic and imaging data from a number of ground based telescopes.

The results of this work have been accepted for publication in the Astrophysical Journal.

NOAO is operated by Association of Universities for Research in Astronomy Inc. (AURA) under a cooperative agreement with the National Science Foundation.

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Do bacteria age? Biologists discover the answer follows simple economics

ScienceDaily (Oct. 27, 2011) — When a bacterial cell divides into two daughter cells and those two cells divide into four more daughters, then 8, then 16 and so on, the result, biologists have long assumed, is an eternally youthful population of bacteria. Bacteria, in other words, don't age -- at least not in the same way all other organisms do.

But a study conducted by evolutionary biologists at the University of California, San Diego questions that longstanding paradigm. In a paper published in the November 8 issue of the journal Current Biology, they conclude that not only do bacteria age, but that their ability to age allows bacteria to improve the evolutionary fitness of their population by diversifying their reproductive investment between older and more youthful daughters. An advance copy of the study appears this week in the journal's early online edition.

"Aging in organisms is often caused by the accumulation of non-genetic damage, such as proteins that become oxidized over time," said Lin Chao, a professor of biology at UC San Diego who headed the study. "So for a single celled organism that has acquired damage that cannot be repaired, which of the two alternatives is better -- to split the cellular damage in equal amounts between the two daughters or to give one daughter all of the damage and the other none?"

The UC San Diego biologists' answer -- that bacteria appear to give more of the cellular damage to one daughter, the one that has "aged," and less to the other, which the biologists term "rejuvenation" -- resulted from a computer analysis Chao and colleagues Camilla Rang and Annie Peng conducted on two experimental studies. Those studies, published in 2005 and 2010, attempted unsuccessfully to resolve the question of whether bacteria aged. While the 2005 study showed evidence of aging in bacteria, the 2010 study, which used a more sophisticated experimental apparatus and acquired more data than the previous one, suggested that they did not age.

"We analyzed the data from both papers with our computer models and discovered that they were really demonstrating the same thing," said Chao. "In a bacterial population, aging and rejuvenation goes on simultaneously, so depending on how you measure it, you can be misled to believe that there is no aging."

In a separate study, the UC San Diego biologists filmed populations of E. coli bacteria dividing over hundreds of generations and confirmed that the sausage-shaped bacteria divided each time into daughter cells that grew elongated at different rates -- suggesting that one daughter cell was getting all or most of the cellular damage from its mother while the other was getting little or none. Click this link to watch the time-lapse film of one bacterium dividing over 10 generations into 1,000 bacteria in a period of five hours and see if you can see any differences.

"We ran computer models and found that giving one daughter more the damage and the other less always wins from an evolutionary perspective," said Chao. "It's analogous to diversifying your portfolio. If you could invest $1 million at 8 percent, would that provide you with more money than splitting the money and investing $500,000 at 6 percent and $500,000 at 10 percent?"

"After one year it makes no difference," he added. "But after two years, splitting the money into the two accounts earns you more and more money because of the compounding effect of the 10 percent. It turns out that bacteria do the same thing. They give one daughter a fresh start, which is the higher interest-bearing account and the other daughter gets more of the damage."

Although E. coli bacteria appear to divide precisely down the middle into two daughter cells, the discovery that the two daughters eventually grow to different lengths suggests that bacteria do not divide as symmetrically as most biologists have come to believe, but that their division is really "asymmetrical" within the cell.

"There must be an active transport system within the bacterial cell that puts the non-genetic damage into one of the daughter cells," said Chao. "We think evolution drove this asymmetry. If bacteria were symmetrical, there would be no aging. But because you have this asymmetry, one daughter by having more damage has aged, while the other daughter gets a rejuvenated start with less damage."

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The above story is reprinted from materials provided by University of California - San Diego. The original article was written by Kim McDonald.

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Journal Reference:

Camilla U. Rang, Annie Y. Peng, Lin Chao. Temporal Dynamics of Bacterial Aging and Rejuvenation. Current Biology, 27 October 2011 DOI: 10.1016/j.cub.2011.09.018

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How to Discover Cheap Auto Insurance Online

Most people don’t fully understand auto insurance. Yes, they might comprehend the basic fundamentals, but they don’t know how to lower their rates by themselves. This is why many recommend finding a knowledgeable agent or doing some research so you know what you need when looking for affordable policies. This information is also important to know when you are looking for cheap auto insurance online.

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Discover The Importance Of Stock And Forex Trading Training

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