Multicolor image from the Pan-STARRS1 telescope of the free-floating
planet PSO J318.5-22, in the constellation of Capricornus. The planet is
extremely cold and faint, about 100 billion times fainter in optical
light than the planet Venus. Most of its energy is emitted at infrared
wavelengths. The image is 125 arcseconds on a side. Credit: N. Metcalfe
& Pan-STARRS 1 Science Consortium
WIRCam stacked image of the newly discovered planet. Credits: Dr. Trent Dupuy, Harvard-Smithsonian Center for Astrophysics.
An international team of astronomers has discovered an exotic young planet that is not orbiting a star. This free-floating planet is just 80 light-years away from Earth and has a mass only six times that of Jupiter. The planet formed a mere 12 million years ago—a newborn in terms of planetary lifetimes.
During the past decade, extrasolar planets have been discovered at an
incredible pace, with about a thousand found by indirect methods such
as wobbling or dimming of their host stars induced by the planet.
However, only a handful of planets have been directly imaged, all of
which are around young stars, less than 200 million years old. These
planets are hard to study because they are right next to their bright
host star. In order to understand the physical properties of these
planets, astronomers compare them to cold and low mass brown dwarfs that
are isolated thus much easier to study. The idea is that the smallest
and coldest dwarf stars will have similar properties than those of the
giant planets. However, efforts to link these two classes of objects
together have so far been unsuccessful. These planets are truly unique
objects.
Using the Pan-STARRS1 (PS1) wide-field survey telescope on Haleakala,
Maui, an international team of astronomers identified an object with a
faint and unique heat signature. Follow-up observations using IRTF,
Gemini, UKIRT and CFHT on Mauna Kea show that it has properties similar
to those of gas-giant planets found orbiting around young stars. This
free-floating planet, dubbed PSO J318.5-22, is just 80 light-years away
from Earth and has a mass only six times that of Jupiter. PSO J318.5-22
is one of the lowest-mass free-floating objects known, perhaps the very
lowest. But its most unique aspect is its similar mass, color, and
energy output to directly imaged planets.
The team did astrometric monitoring of PSO J318.5-22 obtaining 9
epoch over two years using WIRCam on CFHT. The resulting median
astrometric precision per epoch is 4.0 milliarcseconds, a stunningly
precise measurement for such a faint, cool object. This allowed the
direct determination of the distance to PSO J318.5-22 and it's absolute J
band magnitude, important parameters for this type of study. Also,
using the high precision astrometry provided by WIRCam, the team was
able to conclude that PSO J318.5-22 belongs to a collection of young
stars called the Beta Pictoris moving group that formed about 12 million
years ago thus determining the age of PSO J318.5-22.
The discovery paper of PSO J318.5-22 is being published by Astrophysical Journal Letters and is available from the arXiv.
The key authors of the paper are the lead author, Dr. Michael Liu
(Institute for Astronomy at the University of Hawaii at Manoa), Dr.
Niall Deacon (Max Planck Institute for Astronomy, Germany), Dr. Katelyn
Allers (Bucknell University), Dr. Trent Dupuy (Harvard-Smithsonian
Center for Astrophysics), and Michael Kotson and Kimberly Aller
(University of Hawaii at Manoa).
For more Information, please see the official press release.
Canada-France-Hawaii Telescope
Contacts:Dr. Michael Liu
mliu@ifa.hawaii.edu
+1-808-956-6666
Dr. Eugene Magnier
eugene@ifa.hawaii.edu
+1-808-232-8440
Louise Good
Media contact
good@ira.hawaii.edu
+1-808-956-9403
Source: Canada-France-Hawaii Telescope
