14 DAY TRIAL // A team of astronomers proposes that the main reason why experts cannot find hot Jupiter-class exoplanets around stars in clusters is the fact that these cosmic fireballs have already destroyed them.
Very few of the numerous studies conducted on such parent stars have evidenced the existence of occultations, which is a dimming in the apparent brightness of a star for a short period of time.
In astronomy, this is taken as a sign that a body has passed in between the star and Earth. If the phenomenon reoccurs, then the existence of an exoplanet around that star is established.
But investigations conducted on stars in clusters have revealed surprisingly low numbers of hot Jupiter planets, which are gas giants as massive as Jupiter, or even more so, but reside close to their parent stars.
In our solar system, the smaller, rocky planets – Earth, Mars, Mercury and Venus – are located closer to the Sun, whereas the four gas giants – Saturn, Neptune, Uranus and Jupiter – are located very far away.
This means that their surface temperatures are significantly lower than the ones on Mercury, for example. In extrasolar systems, many gas giants are located very close to their stars, hence their names.
“Planets are elusive creatures, and we found another reason that they’re elusive,” says Brian Jackson.
He expert is a NASA Postdoctoral Program fellow at the American space agency's Goddard Space Flight Center (GSFC), in Greenbelt, Maryland. He conducted the work with colleague John Debes.
The two authored a new study on the issue, which was accepted for publication in an upcoming issue of the esteemed Astrophysical Journal, Space Fellowship reports.
The paper also predicts that planet-hunting missions such as the Kepler Telescope have a much higher chance of finding exoplanets in young star clusters than in older ones.
“Globular clusters turn out to be rough neighborhoods for planets, because there are lots of stars around to beat up on them and not much for them to eat,” Jackson explains.
The team goes on to say that most of the 450+ exoplanets that were detect thus far were found around single stars, in regions of space that were not exposed to violent cosmic phenomena.
The future of this field of research looks bleak, experts say. It may be that astronomers may have to change their position about conducting large-scale studies of the skies.
“The big, obvious planets may be gone, so we’ll have to look for smaller, more distant planets,” says Debes.
“That means we will have to look for a much longer time at large numbers of stars and use instruments that are sensitive enough to detect these fainter planets,” he concludes.