Andrew Yee[_1_]
March 13th 08, 03:17 PM
University of California-Santa Cruz
Contact:
Tim Stephens, (831) 459-2495
March 7, 2008
Nearby star should harbor detectable, Earth-like planets
A rocky planet similar to Earth may be orbiting one of our nearest stellar
neighbors and could be detected using existing techniques, according to a
new study led by astronomers at the University of California, Santa Cruz.
The closest stars to our Sun are in the three-star system called Alpha
Centauri, a popular destination for interstellar travel in works of science
fiction. UCSC graduate student Javiera Guedes used computer simulations of
planet formation to show that terrestrial planets are likely to have formed
around the star Alpha Centauri B and to be orbiting in the "habitable zone"
where liquid water can exist on the planet's surface. The researchers then
showed that such planets could be observed using a dedicated telescope.
"If they exist, we can observe them," said Guedes, who is the first author
of a paper describing the new findings. The paper has been accepted for
publication by the Astrophysical Journal.
Coauthor Gregory Laughlin, professor of astronomy and astrophysics at UCSC,
said a number of factors converge to make Alpha Centauri B an excellent
candidate for finding terrestrial planets. The Doppler detection method,
which has revealed the majority of the 228 known extrasolar planets,
measures shifts in the light from a star to detect the tiny wobble induced
by the gravitational tug of an orbiting planet. Factors that favor the use
of this technique for Alpha Centauri B include the brightness of the star
and its position in the sky, which gives it a long period of observability
each year from the Southern Hemisphere, Laughlin said.
Detecting small, rocky planets the size of Earth is challenging, however,
because they induce a relatively small wobble in their host stars. According
to Laughlin, five years of observations using a dedicated telescope would be
needed to detect an Earth-like planet around Alpha Centauri B.
Coauthor Debra Fischer of San Francisco State University is leading an
observational program to intensively monitor Alpha Centauri using the
1.5-meter telescope at the Cerro Tololo Inter-American Observatory in Chile.
The researchers hope to detect real planets similar to the ones that emerged
in the computer simulations.
"I think the planets are there, and it's worth a try to have a look,"
Laughlin said.
To study planet formation around Alpha Centauri B, the team ran repeated
computer simulations, evolving the system for the equivalent of 200 million
years each time. Because of variations in the initial conditions, each
simulation led to the formation of a different planetary system. In every
case, however, a system of multiple planets evolved with at least one planet
about the size of Earth. In many cases, the simulated planets had orbits
lying within the habitable zone of the star.
In addition to Guedes, Laughlin, and Fischer, the authors of the paper
include UCSC postdoctoral researcher Eugenio Rivera and graduate student
Erica Davis, and Elisa Quintana of the SETI Institute. This research was
supported by NASA and the National Science Foundation.
Note to reporters: You may contact Guedes at (831) 459-2774; Laughlin at
(831) 459-3208; and Fischer at (415) 338-1697.
IMAGE CAPTION:
[http://www.ucsc.edu/news_events/img/2008/03/alphacentauri.jpg (71KB)]
An artist's conception of a terrestrial planet in the star system Alpha
Centauri. Image by Mark Fisher.
Contact:
Tim Stephens, (831) 459-2495
March 7, 2008
Nearby star should harbor detectable, Earth-like planets
A rocky planet similar to Earth may be orbiting one of our nearest stellar
neighbors and could be detected using existing techniques, according to a
new study led by astronomers at the University of California, Santa Cruz.
The closest stars to our Sun are in the three-star system called Alpha
Centauri, a popular destination for interstellar travel in works of science
fiction. UCSC graduate student Javiera Guedes used computer simulations of
planet formation to show that terrestrial planets are likely to have formed
around the star Alpha Centauri B and to be orbiting in the "habitable zone"
where liquid water can exist on the planet's surface. The researchers then
showed that such planets could be observed using a dedicated telescope.
"If they exist, we can observe them," said Guedes, who is the first author
of a paper describing the new findings. The paper has been accepted for
publication by the Astrophysical Journal.
Coauthor Gregory Laughlin, professor of astronomy and astrophysics at UCSC,
said a number of factors converge to make Alpha Centauri B an excellent
candidate for finding terrestrial planets. The Doppler detection method,
which has revealed the majority of the 228 known extrasolar planets,
measures shifts in the light from a star to detect the tiny wobble induced
by the gravitational tug of an orbiting planet. Factors that favor the use
of this technique for Alpha Centauri B include the brightness of the star
and its position in the sky, which gives it a long period of observability
each year from the Southern Hemisphere, Laughlin said.
Detecting small, rocky planets the size of Earth is challenging, however,
because they induce a relatively small wobble in their host stars. According
to Laughlin, five years of observations using a dedicated telescope would be
needed to detect an Earth-like planet around Alpha Centauri B.
Coauthor Debra Fischer of San Francisco State University is leading an
observational program to intensively monitor Alpha Centauri using the
1.5-meter telescope at the Cerro Tololo Inter-American Observatory in Chile.
The researchers hope to detect real planets similar to the ones that emerged
in the computer simulations.
"I think the planets are there, and it's worth a try to have a look,"
Laughlin said.
To study planet formation around Alpha Centauri B, the team ran repeated
computer simulations, evolving the system for the equivalent of 200 million
years each time. Because of variations in the initial conditions, each
simulation led to the formation of a different planetary system. In every
case, however, a system of multiple planets evolved with at least one planet
about the size of Earth. In many cases, the simulated planets had orbits
lying within the habitable zone of the star.
In addition to Guedes, Laughlin, and Fischer, the authors of the paper
include UCSC postdoctoral researcher Eugenio Rivera and graduate student
Erica Davis, and Elisa Quintana of the SETI Institute. This research was
supported by NASA and the National Science Foundation.
Note to reporters: You may contact Guedes at (831) 459-2774; Laughlin at
(831) 459-3208; and Fischer at (415) 338-1697.
IMAGE CAPTION:
[http://www.ucsc.edu/news_events/img/2008/03/alphacentauri.jpg (71KB)]
An artist's conception of a terrestrial planet in the star system Alpha
Centauri. Image by Mark Fisher.