Five new Jupiter-like exoplanets have been discovered last month, and now astronomers identify four more that are orbiting stars bigger than our sun. The new exoplanets' sizes range between 2.4 and 5.5 times the size of Jupiter. They can take two to four years to orbit their stars.
The scientists first found the new giant exoplanets in the data collected by several telescopes in Chile. Using a telescope in Australia, they verified the facts and confirmed the existence of four new exoplanets orbiting four massive stars namely HIP8541, HIP74890, HIP84056 and HIP95124.
The discovery adds to the growing trend that stars rich in metal are more likely to host planets. The research was published on March 11.
The research team was led by Matias Jones from the Pontifical Catholic University of Chile. The discovery was first made during the EXoPlanets aRound Evolved StarS (EXPRESS) radial velocity program.
They used two telescopes in Chile's Atacama Desert - La Silla Observatory's 2.2-meter telescope and the Cerro Tololo Inter-American Observatory's 1.5-meter telescope. To confirm the initial findings, they used Australia's 3.9-meter Anglo-Australian telescope.
The researchers initially monitored a sample pool of 166 bright massive stars that can be viewed from the southern hemisphere. They found signal variations in the velocities of the four stars mentioned above. According to the researchers, these could be the effect of the presence of orbiting planets.
"These velocities show periodic signals, with semi-amplitudes between 50 to 100 ms-1, which are likely caused by the doppler shift induced by orbiting companions," wrote the researchers.
The researchers conducted several tests to determine the presence of an inherent indicator in the giant stars. These standard tests included photometric variability, chromospheric emission and line bisector analysis. They found no link between inherent indicators and the observed velocities of the four stars.
The researchers found that massive planets are mostly detected orbiting start that are rich in metal. The discovery adds information on the link between occurrence rate of exoplanets and stellar properties.
"In addition to these planet discoveries, we present a detailed analysis of the mass-metallicity correlations of the planet-hosting and non-planet-hosting stars in our sample, along with studying the fraction of multiple-planet systems observed in giant stars," they wrote in the paper.
Photo : NASA Goddard Space Flight Center | Flickr
