Artist's conception of how WISE 0855 might appear if viewed close-up in
infrared light.
As the Juno mission begins exploring Jupiter in our Solar System, scientists explore a solo world that researchers say looks more similar to Jupiter than any exoplanet yet discovered.
Astronomers have “cracked” a very cold case with the dissection of light
from the coldest known brown dwarf. In fact, the brown dwarf, named
WISE 0855, is billed as the most frigid discrete world yet discovered
beyond our Solar System. The research also presents the strongest
evidence yet for water clouds in the atmosphere of an extrasolar object.
The history of “failed stars” having masses between that of a star and
planet – called brown dwarfs – continues to blur. Now, that distinction
is even more ambiguous with the confirmation that WISE 0855 shares more
of a likeness with Jupiter than many exoplanets.
New evidence for this comes from the first spectroscopy, or light
fingerprint, of the object, performed at the Gemini North telescope in
Hawai’i. The spectrum presents astronomers with the most definitive
evidence ever for water vapor in the atmosphere of an object outside of
our solar system. The research also confirms that temperatures dip to
about 20 below zero Celsius (-10 degrees F) in its cold atmosphere.
WISE 0855 was discovered by Kevin Luhman of Penn State in 2014 using
data from NASA’s Wide-field Infrared Survey Explorer (WISE) satellite.
WISE 0855’s relatively close proximity – it’s only about 7.2 light years
away, the fourth closest extrasolar object to the Sun – provides an
advantage in capturing the object’s miniscule glow; however, it is still
remarkably difficult to observe.
"It's five times fainter than any other object detected with
ground-based spectroscopy at this wavelength," said Andy Skemer of the
University of California Santa Cruz. "Now that we have a spectrum, we
can really start thinking about what's going on in this object. Our
spectrum shows that WISE 0855 is dominated by water vapor and clouds,
with an overall appearance that is strikingly similar to Jupiter."
Skemer is first author of a paper on the new findings to be published in
Astrophysical Journal Letters and currently available online.
“I think everyone on the research team really believed that we were
dreaming to think we could obtain a spectrum of this brown dwarf because
its thermal glow is so feeble,” said Skemer. WISE 0855, is so cool and
faint that many astronomers thought it would be years before we could
dissect its diminutive light into a spectrum. “I thought we’d have to
wait until the James Webb Space Telescope was operating to do this,”
adds Skemer.
The spectrum, obtained using the Gemini North telescope on Hawaii’s
Maunakea, was obtained over a period of 13 nights (about 14 hours of
data collection). “These observations could only be done on a facility
like Gemini North. This is due to its location on Maunakea, where there
is often remarkably little water vapor in the air to interfere with the
sensitive observations, and the technology on the telescope, like its
8-meter silver-coated mirror,” says Jacqueline Faherty of the Carnegie
Department of Terrestrial Magnetism. “We pushed the boundary of what
could be done with a telescope here on Earth. And the result is
spectacular."
The resulting high-quality spectrum reveals water vapor and clouds in
the object’s atmosphere, and opens opportunities to explore the
atmosphere’s dynamics and chemistry. Gemini astronomer, and brown dwarf
researcher, Sandy Leggett explains that the spectrum shows less
phosphine than we see in Jupiter, “...suggesting that the atmosphere may
be less turbulent, since mixing produces the phosphine seen in
Jupiter's atmosphere.”
Results from previous observations of WISE 0855, published in 2014,
provided hints of water clouds based on very limited photometric data
(the relative brightness of specific wavelengths of light). Skemer, also
a coauthor of the 2014 paper, adds that with spectroscopy scientists
are able to separate the object’s light into a wide range of infrared
wavelengths, and probe the body’s molecular composition. “If our eyes
could see infrared light, which is redder than the reddest light we can
see, the data would look like a rainbow of colors.” He adds, “The
relative brightness of each color gives us a glimpse into the
environment of the object’s atmosphere.”
The coauthors of the study include graduate student Caroline Morley and
professor of astronomy and astrophysics Jonathan Fortney at UC Santa
Cruz; Katelyn Allers at Bucknell University; Thomas Geballe at Gemini
Observatory; Mark Marley and Roxana Lupu at NASA Ames Research Center;
Jacqueline Faherty at the Carnegie Institution of Washington; and Gordon
Bjoraker at NASA Goddard Space Flight Center.
Observations for this work were made using the Gemini Near-InfraRed
Spectrograph (GNIRS) which is mounted on the Gemini North telescope on
Maunakea in Hawai‘i. The research team, and Gemini staff, are grateful
to be able to observe from Maunakea, Hawaii’s highest peak, where
conditions are ideal for these types of observations.
University of California, Santa Cruz press release.
A video about the discovery and study of WISE 0855 (rendered using the American Museum of Natural History's Digital Universe) is available at: https://www.youtube.com/watch?v=qT3pvWleFoU.
Media Contacts:
University of California, Santa Cruz press release.
A video about the discovery and study of WISE 0855 (rendered using the American Museum of Natural History's Digital Universe) is available at: https://www.youtube.com/watch?v=qT3pvWleFoU.
Media Contacts:
-
Peter Michaud
Public Information and Outreach
Gemini Observatory, Hilo, HI
Email: pmichaud@gemini.edu
Cell: (808) 936-6643
-
Tim Stephens
University of California, Santa Cruz
Email: stephens@ucsc.edu
Phone: (831) 459-4352
- Andrew Skemer
University of California, Santa Cruz
Email: askemer@ucsc.edu
Phone: (831) 459-5753
- Jacqueline Faherty
Hubble Postdoctoral Fellow
Carnegie Institution for Science
Email: jfaherty17@gmail.com
Cell: (201) 694-0807
- Sandy Leggett
Gemini Observatory
Email: sleggett@gemini.edu
Phone: (808) 974-2604
Source: Gemini Observatory
