* Astronomy

Title: Detection limits for close eclipsing and transiting sub-stellar and planetary companions to white dwarfs in the WASP survey
Authors: F. Faedi, R. G. West, M. R. Burleigh, M. R. Goad, L. Hebb

We have performed extensive simulations to explore the possibility of detecting eclipses and transits of close, sub-stellar and planetary companions to white dwarfs in WASP light-curves. Our simulations cover companions \sim0.3\Re< R_pl<12\Re and orbital periods 2 h<P<15 d, equivalent to orbital radii 0.003 AU < a < 0.1 AU. For Gaussian random noise WASP is sensitive to transits by companions as small as the Moon orbiting a V\simeq12 white dwarf. For fainter white dwarfs WASP is sensitive to increasingly larger radius bodies. However, in the presence of correlated noise structure in the light-curves the sensitivity drops, although Earth-sized companions remain detectable in principle even in low S/N data. Mars-sized, and even Mercury-sized bodies yield reasonable detection rates in high-quality light-curves with little residual noise. We searched for eclipses and transit signals in long-term light-curves of a sample of 194 white dwarfs resulting from a cross-correlation of the McCook & Sion catalogue and the WASP archive. No evidence for eclipsing or transiting sub-stellar and planetary companions was found. We used this non-detection and results from our simulations to place tentative upper limits to the frequency of such objects in close orbits at white dwarfs. While only weak limits can be placed on the likely frequency of Earth-sized or smaller companions, brown dwarfs and gas giants (radius \approx \Rjup) with periods <0.1-0.2~days must certainly be rare (<10%). More stringent constraints likely requires significantly larger white dwarf samples, higher observing cadence and continuous coverage. The short duration of eclipses and transits of white dwarfs compared to the cadence of WASP observations appears to be one of the main factors limiting the detection rate in a survey optimised for planetary transits of main sequence stars.

Read more (129kb, PDF)

SuperWASP is one of the instruments to detect extrasolar planets for greater success in the world. With only four years of life has already discovered a total of 24 celestial objects.

Not a bird, nor a plane, SuperWASP is a small telescope designed to detect extrasolar planets orbiting bright stars.
It does not have cutting-edge technology, nor is it the most innovative. It does not draw attention for being spectacular, not even for being large, but SuperWasp has become one of the greatest discoverers of planets in the universe. Located at the Observatory del Roque de los Muchachos (ORM), on the island of La Palma, and alongside a counterpart from the South African Astronomical Observatory, it is operated continuously throughout the year tracking the visible sky in the northern and southern hemisphere. So far, this system has found a total of 24 extrasolar planets - a real success.

"Debido a su gran campo de visión, SuperWASP puede hacer una imagen de todo el cielo visible en aproximadamente 23 minutos" - Don Pollaco, Principle project investigator, Queen's University Belfast.

Read more (Spanish)

Recently astronomers reported the discovery of 10 extrasolar planets trillions of miles from Earth. That boosts the roster of alien planets to 287 since the first two were identified in 1996.
Read more

Title: SuperWASP-N Extra-solar Planet Candidates from Fields 06hr < RA < 16hr
Authors: S.R. Kane, W.I. Clarkson, R.G. West, D.M. Wilson, D.J. Christian, A. Collier Cameron, B. Enoch, T.A. Lister, R.A. Street, A. Evans, A. Fitzsimmons, C.A. Haswell, C. Hellier, S.T. Hodgkin, K. Horne, J. Irwin, F.P. Keenan, A.J. Norton, J. Osborne, N.R. Parley, D.L. Pollacco, R. Ryans, I. Skillen, P.J. Wheatley

The Wide Angle Search for Planets (WASP) survey currently operates two installations, designated SuperWASP-N and SuperWASP-S, located in the northern and southern hemispheres respectively. These installations are designed to provide high time-resolution photometry for the purpose of detecting transiting extra-solar planets, asteroids, and transient events. Here we present results from a transit-hunting observing campaign using SuperWASP-N covering a right ascension range of 06hr < RA < 16hr. This paper represents the fifth and final in the series of transit candidates released from the 2004 observing season. In total, 729,335 stars from 33 fields were monitored with 130,566 having sufficient precision to be scanned for transit signatures. Using a robust transit detection algorithm and selection criteria, 6 stars were found to have events consistent with the signature of a transiting extra-solar planet based upon the photometry, including the known transiting planet XO-1b. These transit candidates are presented here along with discussion of follow-up observations and the expected number of candidates in relation to the overall observing strategy.

Read more (813kb, PDF)