Spitzer Space Telescope confirms super-Earth nearby
With exoplanets found as far away as 13,000 light years, it appeared that worlds like our own were not in “the neighborhood”. Using NASA’s Spitzer Space Telescope, scientist have confirmed the existence of a rocky planet somewhat similar in size to Earth – and it is just 21 light-years away.
The initial discovery of the exoplanet, designated HD219134b, was made by the High Accuracy Radial velocity Planet Searcher (HARPS-North) instrument on the Italian 3.6 meter Galileo National Telescope. This telescope is located in the Canary islands off the coast of Morocco. The reflecting telescope is one of the largest operated by the Roque de Los Muchachos Observatory.
In addition to HD219134b, the HARPS-North instrument also found three more planets in the same system. However, these other worlds were located further out from their parent star.
“Most of the known planets are hundreds of light-years away. This one is practically a next-door neighbor,” said astronomer Lars A. Buchhave of the Harvard-Smithsonian Center for Astrophysics. Buchhave along with Michael Gillon of the University of Liege in Belgium are the authors of the study on HD219134b.
This exoplanet was found using what is known as the ‘transit’ method. The technique looks for the dimming of a star as a planet or other body passes between the observer and the star. By watching for subtle shifts in the light, it is possible to determine the orbit of any planets in the star system.
This technique generally requires planets that transit their stars rather rapidly. In this case, HD219134b orbits its parent star every three days. Using a technique know as radial velocity (the gravity pull of the planet on its parent star), the planet’s mass was determined to be 4.5 times that of Earth.
The Spitzer telescope followed up on these initial observations. The telescope measured the planet using its infrared sensors to help determine the planet’s size.
Spitzer data suggests the planet is about 1.6 times the size of the Earth. With the mass and size known, the density of the planet was then calculated. The result was 3.5 ounces per cubic inch (six grams per cubic centimeter). That density puts HD219134b firmly in the rocky planet category of the so-called super-Earths.
The Spitzer telescope mission is managed for NASA’s Science Mission Directorate by the Jet Propulsion Laboratory (JPL) in Pasadena, California.
Working from an Earth-trailing orbit, some 353 miles (570 km) above our world, Spitzer is an infrared observatory and a part of NASA’s Great Observatories program.
Launched in 2003 with a planned 2.5 to 5 year mission life, Spitzer has provided large amounts of data to scientists at JPL. With its supply of liquid helium long since exhausted, Spitzer continues operating under the Warm Mission program using two remaining onboard instruments. This mission looks to study exoplanets as well as their environments.
While the planet is close in both size and mass to Earth, the similarities end there. HD219134b orbits its parent star a little too close to support life as we know it. The planet is too small to be seen, but its parent star is visible to the naked eye in the Northern Hemisphere. It resides near Polaris (the North star) close to the constellation of Cassiopeia.
Michael Gillon summed up this latest discovery as such, “Now we have a local specimen to study in greater detail. It can be considered a kind of Rosetta Stone for the study of super-Earths.”
Given the relatively close proximity to Earth, additional telescopes will now be programmed to look at HD219134b to see what additional details can be revealed about this distant world.
Joe Latrell is a life-long avid space enthusiast having created his own rocket company in Roswell, NM in addition to other consumer space endeavors. He continues to design, build and launch his own rockets and has a passion to see the next generation excited about the opportunities of space exploration. Joe lends his experiences from the corporate and small business arenas to organizations such as Teachers In Space, Inc. He is also actively engaged in his church investing his many skills to assist this and other non-profit endeavors.