(Press-News.org) Washington, D.C. Astronomers have found a new, potentially habitable Earth-sized planet. It is one of two new planets discovered around the star Gliese 581, some 20 light years away. The planet, Gliese 581g, is located in a "habitable zone"—a distance from the star where the planet receives just the right amount of stellar energy to maintain liquid water at or near the planet's surface. The 11- year study, published in the Astrophysical Journal and posted online at arXiv.org, suggests that the fraction of stars in the Milky Way harboring potentially habitable planets could be greater than previously thought—as much as a few tens of percent.
The new study brings the total number of planets around Gliese 581 to six and, like our own solar system, they orbit their star in nearly circular orbits. The scientists, members of the Lick-Carnegie Exoplanet Survey, collected 11 years of radial velocity data on the star. The radial velocity method looks at a star's tiny movements in response to the gravitational tug from orbiting bodies. The team tracked the motion of the planets to a precision of about 1.6 meters per second.
The amplitude and phasing of the star's subtle gravitational reactions allow researchers to determine a planet's mass and orbital period. The planet's radius is estimated by making assumptions about its composition, and its surface gravity is calculated from its mass and radius. Astronomers can also determine the planet's equilibrium and surface temperatures, which help to determine the potential for habitability. Equilibrium temperature reflects the balance between the energy emitted from the planet and the thermal energy received from the star. The surface temperature is estimated by the planet's distance from the star and a range of guesses about the composition of its atmosphere. To be habitable, the temperatures must not be too hot, which would vaporize water, nor too cold.
"Our calculations indicate that the planet is between 3.1 and 4.3 Earth masses, has a circular 36.6-day orbit, and a radius estimated between 1.2 and 1.5 Earth radii," remarked co-author Paul Butler of Carnegie's Department of Terrestrial Magnetism.
Its semi-major axis—half the length through the long direction of its elliptical orbital path—is 0.146 astronomical units (one AU is the distance between the Earth and the Sun), and its surface gravity is similar to Earth's at 1.1 to 1.7 g.
Habitability depends on many factors, not just the temperature. The gravity has to be strong enough to hold an atmosphere, for instance, and the temperature must be lower than about 26° F somewhere on the planet. The researchers estimate that the surface temperature of the newly discovered planet is between -24° F and 10° F. The surface would be blazing hot on the side facing the star and freezing cold on the dark side. The planet might be tidally locked to the star—with one side always facing the star, and the other side always dark and cold. This serves to stabilize the planet's surface climates, according to Steven Vogt, co-author and professor of astronomy and astrophysics at UC Santa Cruz. The most habitable zone on the planet's surface would be along the line between shadow and light, with surface temperatures decreasing toward the dark side and increasing toward the light side.
Temperatures on Earth vary tremendously, and life can thrive in very extreme environments, ranging from Antarctica, where the temperature can get to -94 ° F, to extremely hot hydrothermal vents, which roil at 235 ° F.
The fact that the researchers were able to detect this planet so quickly and so nearby (in astronomical terms) suggests that habitable planets could be quite common.
###
NSF will host a press briefing 1 p.m. EDT, Sept. 29
For more information on the briefing contact
Lisa-Joy Zgorski, NSF (703) 292-8311 lisajoy@nsf.gov
Authors on the paper are Steven Vogt, UCO/Lick Observatory, UCSC; Paul Butler Carnegie Institution, Department of Terrestrial Magnetism; UCSC associate research scientist Eugenio Rivera; Associate Astronomer Nader Haghighipour of the Institute for Astronomy at University of Hawaii-Manoa; and Professor Gregory Henry and Michael Williamson of Tennessee State University. The research was funded by the NSF, NASA, and Carnegie.
The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
END
CHICAGO --- A phase II clinical trial of the first new type of drug for musculoskeletal pain since aspirin shows that it significantly reduces knee pain in osteoarthritis, the most common osteoarthritis pain, according to new research from Northwestern Medicine.
However, phase III trials of that drug, tanezumab, have been placed on clinical hold after 16 out of several thousand participants in the new trial developed progressively worsening arthritis and bone changes that required total joint replacements.
"The bottom line is this is a very effective drug for relieving ...
September 29, 2010 ─ (BRONX, NY) ─ A seemingly simple inherited trait – height – springs from hundreds of genetic causes, according to an international team of scientists. Robert Kaplan, Ph.D., professor of epidemiology & population health at Albert Einstein College of Medicine of Yeshiva University, is co-author of a paper on the group's findings published in the September 29 online edition of Nature.
The study identified hundreds of gene variants in at least 180 locations that influence adult height. These results prove that with internet technology it ...
New Haven, Conn.—The rules that govern the world of the very small, quantum mechanics, are known for being bizarre. One of the strangest tenets is something called quantum entanglement, in which two or more objects (such as particles of light, called photons) become inextricably linked, so that measuring certain properties of one object reveals information about the other(s), even if they are separated by thousands of miles. Einstein found the consequences of entanglement so unpalatable he famously dubbed it "spooky action at a distance."
Now a team led by Yale researchers ...
(SACRAMENTO, Calif.) — Just months after a pharmaceutical company halted studies of tanezumab, a drug used in reducing pain and improving function in people with moderate-to-severe osteoarthritis of the knee, the results of a small, phase II clinical trial found only a few minor side effects and substantial improvement in patient conditions. The results of the 16-week study are published in the Sept. 30 issue of The New England Journal of Medicine. Other, longer-term studies have indicated that tanezumab may accelerate osteoarthritis, and the company that manufactures the ...
Research published today provides the first direct evidence that attention-deficit/hyperactivity disorder (ADHD) is a genetic condition. Scientists at Cardiff University found that children with ADHD were more likely to have small segments of their DNA duplicated or missing than other children.
The study also found significant overlap between these segments, known as copy number variants (CNVs), and genetic variants implicated in autism and schizophrenia, proving strong evidence that ADHD is a neurodevelopmental disorder – in other words, that the brains of children ...
A particularly aggressive childhood cancer can be fought successfully with far less chemotherapy than previously believed, avoiding harmful side effects caused by cancer drugs.
The 96 percent survival rate found in an eight-year clinical trial at the University of California, San Francisco, stands to change the approach toward fighting intermediate-risk – stage three and stage four – neuroblastoma. Neuroblastoma attacks the network of cells that control the body's response to stress, known as the sympathetic nervous system, and affects 650 children in the United States ...
Many researchers have studied the relationship between the increase in sales of new antidepressants in recent decades and a simultaneous decline in the suicide rate. In a study based on figures from the Nordic countries, researchers at the Norwegian Institute of Public Health found no evidence that increased sales of the new medicines could be linked to a lower suicide rate. The researchers also did not find any relationship between reduced sales of the older and more toxic antidepressants and a reduction in suicide rates.
The suicide rate has been declining since the ...
Severe sepsis, a disease characterised by a sudden drop in blood pressure and progressive organ dysfunction following infection, remains one of the most common causes of mortality in intensive care units worldwide. Even under the best possible medical conditions, mortality rates range between 30 and 70%. A research team from the Instituto Gulbenkian de Ciência, Portugal, led by Miguel Soares, found that free heme, released from red blood cells during infection, is the cause of organ failure, leading to the lethal outcome of severe sepsis. Moreover this team found that the ...
The key to the stability of any building is its foundation, but it is difficult to test some building sites in advance – such as those on the moon. New research from North Carolina State University is helping resolve the problem by using computer models that can utilize a small sample of soil to answer fundamental questions about how soil at a building site will interact with foundations.
"If you are going to build a large structure, you have to run a lot of tests on the building site to learn how the soil will behave in relation to the building's foundation," says Dr. ...
Athens, Ga. – A new University of Georgia study suggests that mothers who consume a diet high in trans fats double the likelihood that their infants will have high levels of body fat.
Researchers, whose results appear in the early online edition of the European Journal of Clinical Nutrition, found that infants whose mothers consumed more than 4.5 grams of trans fats per day while breastfeeding were twice as likely to have high percentages of body fat, or adiposity, than infants whose mothers consumed less than 4.5 grams per day of trans fats.
The researchers investigated ...
