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Astronomy/Discovering Extrasolar Planets

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Expert: - 1/9/2008


Question
Dear Mr. Whiting,

One of the most commonly used methods for finding planets is observing the wobble of a star, but is there anything else that could cause a star to exhibit similar behavior to a star with a planetary companion, and if so what would it be?

Thank you for your time,
-Zach

Answer
Hi Zach,
Actually, the "wobble" method (side-to-side motion) is
the least used now.  The most accurate and most used method
is the (change in) recessional/approach velocity of the star, as we have very sensitive equipment that can measure the recessional velocity, (actually acceleration) down to 1 or 2 feet per second, or change in velocity,  away (or toward) us. This is currently the most successful method.

The next best method, is on rare occasions, when the system is presented edge-on to our line of sight, the giant planet actually transits (passes right in front of) the star, so astronomers can measure the minute drop in light from the star, because we have very sensitive equipment that can do that too.  The "wobble" method is now a last resort, as it takes so long to determine a slight wobble sideways, so that method is the least used now.  The other two methods described above are the most accurate and most successful.
Hope this helps,
Clear skies,
Tom Whiting
Erie, PA

FOLLOW UP:
Oh, but to answer your original question, NO, there is
no other reason known that would cause a star to "wobble"
except for another body in orbit around said star.....
that's why we can be certain that there is an "unseen
companion" to that star IF the star "wobbles" in it's
orbit.
Clear skies,
tom

Astronomy

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Tom Whiting

Expertise

Astronomy has been my hobby/pasttime for over 50 years.  Currently own 3 telescopes, the largest of which is a 30 inch Newtonian truss Dob that is portable.I taught Astronomy/Meteorology at the University Level for 13 years before retiring in 1995. Being retired and home most of the time, I am able to answer all questions relatively quickly, unless it's a new moon weekend with good observing conditions.  No astrology questions please, or questions about alleged UFO picture identifications.

Experience

Experience: Astronomy has been my hobby and study for over 50 years. We currently now own a 30 inch portable telescope (Updated - Pennsylvania`s largest portable telescope). It can be seen on our website at:http://www.velocity.net/~bwhiting and also attend several regional starparties during the year, and have been on 5 total solar eclipse expeditions.

Organizations: President, Erie County Mobile Observers Group for over 15 years.

Publications: Wrote the "Over Erie Skies" newspaper article in our local newspaper for 11 years (1975-86).

Education: Masters Degree- Taught at the University level for 13 years. Retired 20 years -USAF Pilot - KC-135 with 180 combat missions;  Also Eagle Scout, Philmont staff 2 Yrs, Order of Arrow Lodge Chief, Ham Radio (inactive).

Awards: two discoveries: The mini-coathanger asterism in Ursa Minor (the little dipper) And the mini-ladle- another asterism in the bowl of Ursa Minor. Clients: Currently President of the ECMOG as mentioned above.

Education/Credentials
BS  Metallurgical Engineering Grove City College, PAMaster's Degree, Gannon University, Erie, PA Also retired USAF pilot, 20 years.

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