Astronomers develop method to infer exoplanet masses from dust ring features
Astronomers have discovered a way to use the rings carved by young exoplanets in protoplanetary disks to assess the characteristics of those planets, even when they are too faint or deeply embedded to observe directly. The team, led by Amena Faruqi of the University of Warwick, used computer simulations to show that the width of a dust ring and the location of its brightest point are key to determining the mass of the hidden planet. The relationship between a planet’s mass and the peak brightness of its dust ring holds regardless of the wavelength of light used or the size of the dust grains. The researchers tested their technique on the PDS 70 system, located about 370 light-years away, which hosts at least two confirmed exoplanets (PDS 70 b and PDS 70 c) and has been directly imaged. Their method estimated the mass of PDS 70 c at about 7.5 times the mass of Jupiter, consistent with current estimates. The simulations also revealed that massive forming planets can trap up to 20 Earth masses of dust in their rings, raising new questions about why additional planets have not been detected in that trapped material. The findings were published Thursday, May 28, in The Astrophysical Journal.
What’s reported
The technique uses the width and brightness peak of dust rings in protoplanetary disks to infer the mass of embedded exoplanets.
The relationship between planet mass and ring peak brightness is independent of imaging wavelength and dust grain size.
The method was validated on the PDS 70 system, located 370 light-years away, which has two known exoplanets (PDS 70 b and PDS 70 c).
The team’s mass estimate for PDS 70 c was about 7.5 Jupiter masses, matching prior estimates.
Simulations indicate that massive planets can trap as much dust as 20 Earth masses within rings.
The research was published in The Astrophysical Journal on May 28.
Open questions
Why new planets have not been detected in the trapped dust and pebbles within rings, despite the dust being abundant and concentrated enough to potentially kick off planet formation.
Key figures
Amena Faruqi – team leader, Astronomy and Astrophysics Group, University of Warwick
Jessica Speedie – Massachusetts Institute of Technology (MIT)
Ralph Pudritz – Department of Physics and Astronomy, McMaster University
Farzana Meru – Department of Physics, University of Warwick
PDS 70 b – one of two exoplanets in the PDS 70 system
PDS 70 c – the other exoplanet in the PDS 70 system
Sources: space.com
