Hubble spots ‘exocomets’ taking plunge into young star
On 7th January, NASA’s Hubble Space Telescope has discovered “exocomets” plunging onto the star HD 172555, which is a youthful 23 million years old and resides 95 light-years from Earth.
The exocomets – outside our solar system, were not directly seen around the star, but their presence was inferred by detecting gas that is likely the vaporized remnants of their icy nuclei. HD 172555 represents the third extrasolar system where astronomers have detected doomed, wayward comets. All of the systems are young, under 40 million years old, NASA said in a statement.
Astronomers have found similar plunges in our own solar system. Sun-grazing comets routinely fall into our sun. The presence of these doomed comets provides circumstantial evidence for “gravitational stirring” by an unseen Jupiter-size planet, where comets deflected by its gravity are catapulted into the star.
“Seeing these sun-grazing comets in our solar system and in three extrasolar systems means that this activity may be common in young star systems,” said study leader Carol Grady from NASA’s Goddard Spaceflight Center in Greenbelt, Maryland.
On the top of that, The stellar group is important to study because it is the closest collection of young stars to Earth. At least 37.5 percent of the more massive stars in the Beta Pictoris Moving Group either have a directly imaged planet, such as 51 Eridani b in the 51 Eridani system, or infalling star-grazing bodies, or, in the case of Beta Pictoris, both types of objects.
The telescope detected silicon and carbon gas in the starlight. The gas was moving at about 360,000 miles per hour across the face of the star. The most likely explanation for the speedy gas is that Hubble is seeing material from comet-like objects that broke apart after streaking across the face of the star. The gaseous debris from the disintegrating comets is vastly dispersed in front of the star. “As transiting features go, this vaporized material is easy to see because it contains very large structures,” Grady said.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA Goddard manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.