Featured Research

from universities, journals, and other organizations

Hubble Zeroes In On Nearest Known Exoplanet, Confirms That Planets Form From Disks Around Stars

Date:
October 9, 2006
Source:
Space Telescope Science Institute
Summary:
NASA's Hubble Space Telescope, in collaboration with ground-based observatories, has provided definitive evidence for the existence of the nearest extrasolar planet to our solar system. The Jupiter-sized world orbits the Sun-like star Epsilon Eridani, which is only 10.5 light-years away (approximately 63 trillion miles). The planet is so close it may be observable by Hubble and large ground-based telescopes in late 2007, when the planet makes its closest approach to Epsilon Eridani during its 6.9-year orbit.

This is an artist's concept of a Jupiter-mass planet orbiting the nearby star Epsilon Eridani. Located 10.5 light-years away, it is the closest known exoplanet to our solar system. The planet is in an elliptical orbit that carries it as close to the star as Earth is from the Sun, and as far from the star as Jupiter is from the Sun.
Credit: NASA, ESA, and G. Bacon (STScI)

NASA's Hubble Space Telescope, in collaboration with ground-based observatories, has provided definitive evidence for the existence of the nearest extrasolar planet to our solar system.

The Jupiter-sized world orbits the Sun-like star Epsilon Eridani, which is only 10.5 light-years away (approximately 63 trillion miles). The planet is so close it may be observable by Hubble and large ground-based telescopes in late 2007, when the planet makes its closest approach to Epsilon Eridani during its 6.9-year orbit.

The Hubble observations were achieved by a team led by G. Fritz Benedict and Barbara E. McArthur of the University of Texas at Austin. The observations reveal the the planet's true mass, which the team has calculated to be 1.5 times Jupiter's mass.

Hubble also found that the planet's orbit is tilted 30 degrees to our line of sight, which is the same inclination as a disk of dust and gas that also encircles Epsilon Eridani. This is a particularly exciting result because, although it has long been inferred that planets form from such disks, this is the first time that the two objects have been observed around the same star.

The research team emphasized that the alignment of the planet's orbit with the dust disk provides compelling direct evidence that planets form from disks of gas and dust debris around stars.

The planets in our Solar System share a common alignment, evidence that they were created at the same time in the Sun's disk. But the Sun is a middle-aged star -- 4.5 billion years old -- and its debris disk dissipated long ago. Epsilon Eridani, however, still retains its disk because it is young, only 800 million years old.

McArthur originally detected the planet in 2000 by measurements that were interpreted as a rhythmic, back-and-forth wobble in Epsilon Eridani caused by the gravitational tug of an unseen planet. However some astronomers wondered if in fact the turbulent motion of the young star's atmosphere was mimicking the effects of the star being nudged by a planet's gravitational pull.

The Hubble observations settle any uncertainty. The Benedict-McArthur team calculated the planet's mass and its orbit by making extremely precise measurements of subtle changes in the star's location in the sky, a technique called astrometry. The slight variations are unmistakably caused by the gravitational tug of the unseen companion object. Benedict's team studied over a thousand astrometric observations from Hubble collected over three years.

"You can't see the wobble induced by the planet with the naked eye," Benedict said. "But Hubble's fine guidance sensors are so precise that they can measure the wobble. We basically watched three years of a nearly seven-year-long dance of the star and its invisible partner, the planet, around their orbits. The fine guidance sensors measured a tiny change in the star's position, equivalent to the width of a quarter 750 miles away."

The astronomers combined these data with other astrometric observations made at the University of Pittsburgh's Allegheny Observatory. They then added those measurements to hundreds of ground-based radial-velocity measurements made over the past 25 years at McDonald Observatory at the University of Texas, Lick Observatory at the University of California Observatories, the Canada-France-Hawaii Telescope in Hawaii, and the European Southern Observatory in Chile. This combination allowed them to accurately determine the planet's mass by deducing the tilt of its orbit.

Although Hubble and other telescopes cannot image the gas giant planet now, they may be able to snap pictures of it in 2007, when its orbit is closest to Epsilon Eridani. The planet may be bright enough in reflected starlight to be imaged by Hubble, other space-based cameras, and large ground-based telescopes.

The results will appear in the November issue of the Astronomical Journal.


Story Source:

The above story is based on materials provided by Space Telescope Science Institute. Note: Materials may be edited for content and length.


Cite This Page:

Space Telescope Science Institute. "Hubble Zeroes In On Nearest Known Exoplanet, Confirms That Planets Form From Disks Around Stars." ScienceDaily. ScienceDaily, 9 October 2006. <www.sciencedaily.com/releases/2006/10/061009130532.htm>.
Space Telescope Science Institute. (2006, October 9). Hubble Zeroes In On Nearest Known Exoplanet, Confirms That Planets Form From Disks Around Stars. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2006/10/061009130532.htm
Space Telescope Science Institute. "Hubble Zeroes In On Nearest Known Exoplanet, Confirms That Planets Form From Disks Around Stars." ScienceDaily. www.sciencedaily.com/releases/2006/10/061009130532.htm (accessed October 23, 2014).

Share This



More Space & Time News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Russian Cosmonauts Kick Off Final Spacewalk of 2014

Russian Cosmonauts Kick Off Final Spacewalk of 2014

Reuters - US Online Video (Oct. 22, 2014) — Russian cosmonauts Maxim Suraev and Alexander Samokutyaev step outside the International Space Station to perform work on the exterior of the station's Russian module. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
Comet Siding Spring Grazes Mars' Atmosphere

Comet Siding Spring Grazes Mars' Atmosphere

Newsy (Oct. 19, 2014) — A comet from the farthest reaches of the solar system passed extremely close to Mars this weekend, giving astronomers a rare opportunity to study it. Video provided by Newsy
Powered by NewsLook.com
Latin America Launches Communications Satellite

Latin America Launches Communications Satellite

AFP (Oct. 17, 2014) — Argentina launches a home-built satellite, a first for Latin America. It will ride a French-made Ariane 5 rocket into orbit, and will provide cell phone, digital TV, Internet and data services to the lower half of South America. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
This Week @ NASA, October 17, 2014

This Week @ NASA, October 17, 2014

NASA (Oct. 17, 2014) — Power spacewalk, MAVEN’s “First Light”, Hubble finds extremely distant galaxy and more... Video provided by NASA
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins