* Astronomy

Blobrana · L

RE: WASP-5b

Blobrana · L

Title: Transit Monitoring in the South (TraMoS) project: Discarding Transit Timing Variations in WASP-5b
Authors: S. Hoyer (1), P. Rojo (1), M. Lopez-Morales (2,3) ((1) Astronomy Department, Universidad de Chile, (2) Institut de Ciencies de l'Espai (CSIC-IEEC), (3) Visiting Scientist, CIW-DTM)

We report nine new transit epochs of the extrasolar planet, observed in the Bessell-I band with SOAR at the Cerro Pachon Observatory and with the SMARTS 1-m Telescope at CTIO, between August 2008 and October 2009. The new transits have been combined with all previously published transit data for this planet to provide a new Transit Timing Variations (TTVs) analysis of its orbit. We find no evidence of TTVs RMS variations larger than 1 min over a 3 year time span. This result discards the presence of planets more massive than about 5 Earth masses, 1 Earth masses and 2 Earth masses around the 1:2, 5:3 and 2:1 orbital resonances. These new detection limits exceed by ~5-30 times the limits imposed by current radial velocity observations in the Mean Motion Resonances of this system. Our search for the variation of other parameters, such as orbital inclination and transit depth also yields negative results over the total time span of the transit observations. This result supports formation theories that predict a paucity of planetary companions to Hot Jupiters.

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Blobrana · L

Title: Measurements of Transit Timing Variations for WASP-5b
Authors: Akihiko Fukui, Norio Narita, Paul J. Tristram, Takahiro Sumi, Fumio Abe, Yo****aka Itow, Denis J. Sullivan, Ian A. Bond, Teruyuki Hirano, Motohide Tamura, David P. Bennett, Kei Furusawa, Fumiya Hayashi, John B. Hearnshaw, Shun Hosaka, Koki Kamiya, Shuhei Kobara, Aarno Korpela, Pam M. Kilmartin, Wei Lin, Cho Hong Ling, Shota Makita, Kimiaki Masuda, Yutaka Matsubara, Noriyuki Miyake, Yasushi Muraki, Maiko Nagaya, Kenta Nishimoto, Kouji Ohnishi, Kengo Omori, Yvette Perrott, Nicholas Rattenbury, Toshiharu Saito, Ljiljana Skuljan, Daisuke Suzuki, Winston L. Sweatman, Kohei Wada
(Version v2)

We have observed 7 new transits of the `hot Jupiter' WASP-5b using a 61 cm telescope located in New Zealand, in order to search for transit timing variations (TTVs) which can be induced by additional bodies existing in the system. When combined with other available photometric and radial velocity (RV) data, we find that its transit timings do not match a linear ephemeris; the best fit \chi^2 values is 32.2 with 9 degrees of freedom which corresponds to a confidence level of 99.982 % or 3.7 \sigma. This result indicates that excess variations of transit timings has been observed, due either to unknown systematic effects or possibly to real TTVs. The TTV amplitude is as large as 50 s, and if this is real, it cannot be explained by other effects than that due to an additional body or bodies. From the RV data, we put an upper limit on the RV amplitude caused by the possible secondary body (planet) as 21 m s^{-1}, which corresponds to its mass of 22-70 M_{Earth} over the orbital period ratio of the two planets from 0.2 to 5.0. From the TTVs data, using the numerical simulations, we place more stringent limits down to 2 M_{Earth} near 1:2 and 2:1 mean motion resonances (MMRs) with WASP-5b at the 3 \sigma level, assuming that the two planets are co-planer. We also put an upper limit on excess of Trojan mass as 43 M_{Earth} (3 \sigma) using both RV and photometric data. We also find that if the possible secondary planet has non- or a small eccentricity, its orbit would likely be near low-order MMRs. Further follow-up photometric and spectroscopic observations will be required to confirm the reality of the TTV signal, and results such as these will provide important information for the migration mechanisms of planetary systems.

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Blobrana · L

WASP-5b is an extrasolar planet orbiting the star WASP-5 located over 967 light-years away in the constellation Phoenix.

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Position(2000): R.A. 23h 57m 23.74s, Dec. 41º 16 37.5"

Wasp 5b.kmz (2kb, download and rename/add .kmz extension)

Blobrana · L

Title: WASP-5b: a dense, very-hot Jupiter transiting a 12th-mag Southern-hemisphere star
Authors: D. R. Anderson, M. Gillon, C. Hellier, P. F. L. Maxted, F. Pepe, D. Queloz, D. M. Wilson, A. Collier Cameron, B. Smalley, T. A. Lister, S. J. Bentley, A. Blecha, D. J. Christian, B. Enoch, L. Hebb, K. Horne, J. Irwin, Y. C. Joshi, M. Marmier, M. Mayor, N. R. Parley, D. L. Pollacco, F. Pont, R. Ryans, D. Ségransan, I. Skillen, R. A. Street, S. Udry, R. G. West, P. J. Wheatley

We report the discovery of WASP-5b, a Jupiter-mass planet orbiting a 12th-mag G-type star in the Southern hemisphere. The 1.6-d orbital period places WASP-5b in the class of very-hot Jupiters and leads to a predicted equilibrium temperature of 1750 K. WASP-5b is the densest of the very-hot Jupiters, being a factor three denser than planets such as WASP-4b. We present transit photometry and radial-velocity measurements of WASP-5 (= USNO-B1 0487-0799749), from which we derive the mass and radius of the planet: M_P = 1.58 +0.13 -0.08 M_J and R_P = 1.090 +0.094 -0.058 R_J. The orbital period is P = 1.6284296 +0.0000048 -0.0000037 d and the mid-transit epoch is T_C (HJD) = 2454375.62466 +0.00026 -0.00025.

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