[meteorite-list] Can WISE Find the Hypothetical 'Tyche'?

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 18 Feb 2011 13:37:55 -0800 (PST)
Message-ID: <201102182137.p1ILbtMt009989_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2011-060

Can WISE Find the Hypothetical 'Tyche'?
Jet Propulsion Laboratory
February 18, 2011

Background

In November 2010, the scientific journal Icarus published a paper by
astrophysicists John Matese and Daniel Whitmire, who proposed the
existence of a binary companion to our sun, larger than Jupiter, in the
long-hypothesized "Oort cloud" -- a faraway repository of small icy
bodies at the edge of our solar system. The researchers use the name
"Tyche" for the hypothetical planet. Their paper argues that evidence
for the planet would have been recorded by the Wide-field Infrared
Survey Explorer (WISE).

WISE is a NASA mission, launched in December 2009, which scanned the
entire celestial sky at four infrared wavelengths about 1.5 times. It
captured more than 2.7 million images of objects in space, ranging from
faraway galaxies to asteroids and comets relatively close to Earth.
Recently, WISE completed an extended mission, allowing it to finish a
complete scan of the asteroid belt, and two complete scans of the more
distant universe, in two infrared bands. So far, the mission's
discoveries of previously unknown objects include an ultra-cold star or
brown dwarf, 20 comets, 134 near-Earth objects (NEOs), and more than
33,000 asteroids in the main belt between Mars and Jupiter.

Following its successful survey, WISE was put into hibernation in
February 2011. Analysis of WISE data continues. A preliminary public
release of the first 14 weeks of data is planned for April 2011, and the
final release of the full survey is planned for March 2012.

Frequently Asked Questions

Q: When could data from WISE confirm or rule out the existence of the
hypothesized planet Tyche?

A: It is too early to know whether WISE data confirms or rules out a
large object in the Oort cloud. Analysis over the next couple of years
will be needed to determine if WISE has actually detected such a world
or not. The first 14 weeks of data, being released in April 2011, are
unlikely to be sufficient. The full survey, scheduled for release in
March 2012, should provide greater insight. Once the WISE data are fully
processed, released and analyzed, the Tyche hypothesis that Matese and
Whitmire propose will be tested.

Q: Is it a certainty that WISE would have observed such a planet if it
exists?

A: It is likely but not a foregone conclusion that WISE could confirm
whether or not Tyche exists. Since WISE surveyed the whole sky once,
then covered the entire sky again in two of its infrared bands six
months later, WISE would see a change in the apparent position of a
large planet body in the Oort cloud over the six-month period. The two
bands used in the second sky coverage were designed to identify very
small, cold stars (or brown dwarfs) -- which are much like planets
larger than Jupiter, as Tyche is hypothesized to be.

Q: If Tyche does exist, why would it have taken so long to find another
planet in our solar system?

A: Tyche would be too cold and faint for a visible light telescope to
identify. Sensitive infrared telescopes could pick up the glow from such
an object, if they looked in the right direction. WISE is a sensitive
infrared telescope that looks in all directions.

Q: Why is the hypothesized object dubbed "Tyche," and why choose a
Greek name when the names of other planets derive from Roman mythology?

A: In the 1980s, a different companion to the sun was hypothesized. That
object, named for the Greek goddess "Nemesis," was proposed to explain
periodic mass extinctions on the Earth. Nemesis would have followed a
highly elliptical orbit, perturbing comets in the Oort Cloud roughly
every 26 million years and sending a shower of comets toward the inner
solar system. Some of these comets would have slammed into Earth,
causing catastrophic results to life. Recent scientific analysis no
longer supports the idea that extinctions on Earth happen at regular,
repeating intervals. Thus, the Nemesis hypothesis is no longer needed.
However, it is still possible that the sun could have a distant, unseen
companion in a more circular orbit with a period of a few million years
-- one that would not cause devastating effects to terrestrial life. To
distinguish this object from the malevolent "Nemesis," astronomers chose
the name of Nemesis's benevolent sister in Greek mythology, "Tyche."

JPL manages and operates the Wide-field Infrared Survey Explorer for
NASA's Science Mission Directorate, Washington. The principal
investigator, Edward Wright, is at UCLA. The mission was competitively
selected under NASA's Explorers Program managed by the Goddard Space
Flight Center, Greenbelt, Md. The science instrument was built by the
Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by
Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations
and data processing take place at the Infrared Processing and Analysis
Center at the California Institute of Technology in Pasadena. Caltech
manages JPL for NASA. More information is online at
http://www.nasa.gov/wise, http://wise.astro.ucla.edu and
http://www.jpl.nasa.gov/wise <http://www.jpl.nasa.gov/wise > .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin at jpl.nasa.gov
Received on Fri 18 Feb 2011 04:37:55 PM PST