Magnetic
Planet01.08.04(Source: Canadian National
Research Council)National Research
Council
Ottawa,
Canada
CONTACTS:
Evgenya
Shkolnik
University of British Columbia
Tel:
250.595.3801
email: shkolnik@physics.ubc.ca
http://www.astro.ubc.ca/http://www.physics.ubc.ca/Gordon
Walker
University of British Columbia
Tel:
250.592.6205
email: walker@astro.ubc.ca
David
Bohlender
National Research Council of Canada /
Herzberg Institute for Astrophysics
Tel:
250.363.0025
email: David.Bohlender@nrc.ca
http://www.hia.nrc.ca/FOR
RELEASE: 9:00 AM EST, January 7, 2004
PLANET
CREATES A STELLAR STORM
FIRST EVIDENCE OF AN
EXTRA-SOLAR PLANET WITH A MAGNETIC FIELD
Canadian
astronomers announced today the first evidence of a
magnetic field on a planet outside of our solar system
which is also the first observation of a planet heating
its star. The report was presented this morning by Ph.D.
candidate Evgenya Shkolnik, Dr. Gordon Walker, both of
the University of British Columbia, Vancouver, BC and
Dr. David Bohlender of the National Research Council of
Canada / Herzberg Institute for Astrophysics, Victoria,
BC at the meeting of the American Astronomical Society
in Atlanta, Georgia. The result may offer clues about
the structure and formation of the giant
planet.
The trio observed the sun-like star
HD179949 with the 3.6-meter (142-in)
Canada-France-Hawaii Telescope atop Mauna Kea, Hawaii (a
14,000-ft. dormant volcano) using its high-resolution
spectrograph called Gecko. HD179949 is 90 light years
away in the direction of the southern constellation of
Sagittarius (the Archer) but it is too faint to be seen
without a telescope. It was first reported to have a
close-in planet by Tinney, Butler, Marcy and others in
the first results of the Anglo-Australian planet search
in 2000. The planet is at least 270 times more massive
than the Earth, almost as big as Jupiter, and orbits the
star every 3.093 days at 350,000 mph. Such tightly
orbiting "roasters" or "hot jupiters" make up 20% of all
known extrasolar planets.
The star's
chromosphere, a thin, hot layer just above the visible
photosphere, was observed in the ultraviolet light
emitted by singly-ionized Calcium atoms. Giant magnetic
storms produce hot spots which are visible as bright
patches in this light. Such a persistent hotspot is
observed on HD 179949 keeping pace with the planet in
its 3-day orbit for more than a year (or 100 orbits)!
The hotspot appears to be moving across the surface of
the star slightly ahead of, but keeping pace with the
planet. Most evidence suggests the star is rotating too
slowly to carry the spot around so quickly.
The
best explanation for this traveling hot spot is an
interaction between the planet's magnetic field and the
star's chromosphere, something predicted by Steve Saar
of the Center for Astrophysics and Manfred Cuntz of the
University of Texas at Arlington in 2000. If so, this is
the first ever glimpse of a magnetic field on a planet
outside of our solar system, and may provide clues about
the planet's structure and formation.
"If we are
indeed witnessing the entanglement of the magnetic field
of a star with that of its planet it gives us an
entirely new insight into the nature of closely bound
planets." -- Dr. Gordon Walker
Obviously, more
observations are needed to test if the magnetic
interaction is a transient event or something longer
lasting. Also, observations from the 8-meter
Gemini-South Telescope in Chile of this stellar system
are underway in the infrared light emitted by Helium
which would map hotspots at higher levels of the
chromosphere.
This work was supported by the
Canadian Natural Science and Engineering Research
Council and the National Research Council of
Canada.
IMAGE CAPTION:
[
http://www.astro.ubc.ca/images/flare_400x296.jpg
(16 KB)] Shane Erno's conception of the
flare.
