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SUMMARY:Hints of the fourth planet around upsilon Andromedae - Baluev\, R 
 (Pulkovo Observatory)
DTSTART:20091109T102000Z
DTEND:20091109T104000Z
UID:TALK21394@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:We analyse the array of 288 recently published new and revised
  Lick observatory radial velocity (RV) measurements of $upsilon$ And. The 
 periodogram analysis reveals three RV periodicities of relatively small se
 mi-amplitudes (about 10 m/s)\, in addition to the variations due to three 
 known Jovian planets. These new periods are about 12 years\, 180 and 360 d
 ays. The two latter variations cannot be interpreted as planetary signatur
 es because of the dynamical stability argument. These annual variations ha
 ve to be interpreted as errors in the RV data\, which may have instrumenta
 l or data reduction nature. \n\nThe long-period RV variation may allow sta
 ble orbital configurations and is consistent with the fourth distant plane
 tary companion. Its orbital period is unconstrained from the upper side (l
 onger periods require higher eccentricities\, up to a parabolic orbit)\, b
 ut its minimum mass $m in i$ is likely between 0.5 and 3.0 times Jupiter m
 ass. The condition of the dynamical stability limits the set of possible o
 rbits of the fourth planet to the 3/1\, 4/1\, 5/1\, 6/1 mean-motion resona
 nces with planet d or to longer-period elongated orbits with pericenter di
 stance of 5-6 AU (with semi-major axis larger than ~10 AU). \n\nWe also di
 scuss non-planetary interpretations for the long-term RV variation\, which
  are currently difficult to rule out. Efficient confirmation and verificat
 ion of this planet candidate can be done by means of\, e.g.\, long-term as
 trometry and star magnetic activity monitoring.
LOCATION:Satellite
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