Extrasolar Planets Posters
Presiding: D Winterhalter, Jet Propulsion Laboratory, California Institute of Technology
P21E-01 0830h
Search for Radio Emissions from Extrasolar Planets: The Observation Campaign
Non-thermal, low-frequency radio emissions have been observed for decades from planets in our solar system, and they are also expected from the magnetospheres of extrasolar planets. Particularly from "Hot Jupiters", extrasolar planets of Jupiter size that orbit their primary at very close range (<0.1 AU in some cases), we expect the radiated power to be strong enough to allow detection from Earth. This is because the energy input into a magnetosphere so close to a star is orders of magnitude larger than that experienced by our own Jupiter. Using the new 150 MHz receivers of the Giant Metrewave Radiotelescope (GMRT) in India, we have searched for radio emissions from a sub-set of known "hot Jupiters". We have selected three primary and two backup targets, based on the expected flux density and the level of background noise. No observation of these targets has been attempted previously at these frequencies with the sensitivity and aperture offered by GMRT. Calibrations with GMRT at 150 MHz have confirmed the noise floor to be 2 mJy over a 5 MHz bandwidth. The noise floor is well below the expected flux levels from the targets. Our search strategy included a focus on those planetary emissions that may be caused by impulsive events on the primary star. For this reason, the target primaries where monitored for impulsive events with near-simulatenous optical observations. This paper will describe the campaign, and present the preliminary results.
P21E-02 0830h
Search for Radio Emissions from Extrasolar Planets: Recording and Software Correlation
Theory and observations of solar planets show that extra-solar planets probably emit electron-cyclotron (EC) maser emission and that it may in some cases be orders of magnitude stronger than that from Jupiter. Nevertheless, at the Earth, such signals will be barely detectable. It will not be possible to observe them with university-class telescopes such as are used to study Jupiter. It will require the largest meter wavelength telescopes and antenna time will have to be used efficiently. EC emission is highly dynamic in time with time scales of milliseconds to hours and in frequency on scales of less than one to many tens of MHz. With a hardware signal processor configured to record data with a particular resolution and number of frequency bins, data with other time and frequency characters are not resolved or lost. Currently, the GMRT is the most sensitive radio telescope for extrasolar planet studies. With the availability of the Mark5 VLBI recorder, it is now possible to record both polarizations from all 30 antennas over a 12 hr observing run, with the full 4 bits per sample, on ten disk packs. Of course, various trade-offs can be made to reduce the number of disk packs but it is clear that it is possible to record the raw digited data for later processing. The only serious issue is how much of what kind of RFI is tolerable with only four bit samples. JPL has a software correlator (SoftC) now used routinely in the Deep Space Network. It runs on a Beowulf cluster. Also, JPL operates a much larger cluster for research on which SoftC can run. Besides being able to re-examine the data with different time and frequency resolutions, the baselines can also be phased or weighted to null out confusion caused by intense radio sources. We have obtained data from GMRT in this mode and the results of preliminary analysis is described in another paper at this meeting.
P21E-03 0830h
Search for Radio Emission from Extrasolar Planets: Preliminary Analysis of GMRT Data
In 2004 we carried out a series of short calibration runs using the central square array of the GMRT. At the operating RF of 150 MHz, we have determined that the GMRT has a fantastic sensitivity of 2 mJy over a bandwidth of 5 MHz and a timescale of one hour and is relatively free of RFI between midnight and early morning hours local time. As part of the calibration runs, we have carried out brief observation of UpsAnd with various observing strategies. In early 2005, we were granted observing time on the GMRT during its Cycle 7 observation period. Our focus to date has been in characterizing the large scale structure of the dynamic spectra, identifying RFI and developing filters to remove them. We will present our results from both the short calibrations runs of 2004 as well as those obtained from the 2005 observations. We will also describe techniques for detection of chirps as present in Jupiter observations, including match filter strategies. In addition we will describe some preliminary results for detecting bursts via statistical techniques. We plan to use Jupiter and Saturn data to calibrate our detection efficiency for various strategies. We will also discuss our software package for data analysis and computing strategies that we have adopted on our Beowulf Linux cluster at JPL.