Late Planet-Forming Star Spotted by Herschel
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The star, named TW Hydrae, is estimated to be 10 million years old – older than the age at which stars are thought to be able to produce planets. However, the star still has an accretion disc massive enough to possiblly produce planets. The new findings appear in a paper published recently in the journal Nature.
“We didn’t expect to see so much gas around this star,” said Edwin Bergin, lead on the new research and an astronomer at the University of Michigan. “Typically stars of this age have cleared out their surrounding material, but this star still has enough mass to make the equivalent of 50 Jupiters,”
The new TW Hydrae data comes out of a new technique for estimating the mass of planet-forming discs. Researchers used the Herschel telescope to analyze the light coming from the star and pick out hydrogen deuteride gas, which emits light at the longer infrared wavelengths that Herschel can detect. The measurements have provided the most precise measurement of the disc’s mass to date.
“Before, we had to use a proxy to guess the gas quantity in the planet-forming disks,” said Paul Goldsmith, project scientist for Herschel at NASA’s Jet Propulsion Laboratory(JPL). “This is another example of Herschel’s versatility and sensitivity yielding important new results about star and planet formation.”
The researchers stated that knowing the mass of a star’s gas disc is “crucial” to understanding how planets may form around it. Though they don’t know what TW Hydrae’s massive disc will mean for the system’s future, the astronomers stated that the new data has helped define “a range” of possible future planet configurations.
“The new results are another important step in understanding the diversity of planetary systems in our universe,” said Bergin. “We are now observing systems with massive Jupiters, super-Earths, and many Neptune-like worlds. By weighing systems at their birth, we gain insight into how our own solar system formed with just one of many possible planetary configurations.”
(Image courtesy NASA/JPL-Caltech)