The transit method has now bagged its 13th and 14th planets, both of them ‘hot Jupiters’ so close to their stars that their orbits are two and two and one-half days respectively. That makes for temperatures well over 1800 degrees Celsius, and adds more data points in our improbable collection of massive planets that all but skim their stars as they race around their orbits. One of the new planets, called WASP-1b, is in the constellation Andromeda, and is thought to be 1000 light years distant. WASP-2b, in Delphinius, is some 500 light years away.
Behind the discovery is the UK consortium called SuperWASP — Wide Angle Search for Planets. The astronomers involved are surveying millions of stars from robotic observatories in the Canary Islands and in South Africa. Each observatory uses eight wide-angle cameras, with a field of view 2000 times greater than a conventional astronomical telescope. The goal is to detect the faint dimming of starlight that flags a planetary transit, visible in the ‘light curve’ of stars with a clear transit. In the case of WASP-1b and WASP-2b, the discoveries were later confirmed by radial velocity measurements.
Image: The transit detection process. As the planet passes in front of the star it produces a characteristic ‘light-curve’ whose shape is affected by the size and orbital distance (and hence orbital period) of the planet. SuperWASP constantly monitors the brightness of the stars in its field of view and alerts astronomers to any variations that may be due to the presence of a planet. Credit: SuperWASP.
I see that the SuperWASP team is still working with 2004 data (although its Web site doesn’t make it clear when the data on these new planets were gathered), but they seem to have enough interesting light-curves to feel confident that their transit effort will produce big results. The work was announced at the Transiting Extrasolar Planets Workshop at the Max Planck Institute for Astronomy in Heidelberg on September 26. The paper, available as a preprint, is Cameron et al., “WASP-1b and WASP-2b: Two new transiting exoplanets detected with SuperWASP and SOPHIE,” which has been submitted to the Monthly Notices of the Royal Astronomical Society.
Questions from a layman: would this technique or any other be able to detect the existence of a solar system such as ours, even if it were as close as Alpha Centauri? Even just a Jupiter sized planet orbiting at Jupiter’s distance and frequency?
I imagine that the fact that every planet we find seems to be either gigantic and/or in a very tight orbit is more a function of our technological limits than that these types of planets are more common than others. But what are the prospects of actually finding small rocky planets, at least in our immediate neighborhood? Would it likely come from further precision in the methods used now, or do you think there may be a different technique that would theoretically be more suitable?
Sorry if this has already been asked and answered here, I just found the blog and haven’t spent too much time in the archives yet.
Transit methods, as of today, work best with larger objects — finding an Earth-sized planet or smaller around a Sun-like star would be quite difficult, though in a few years we’ll have space-based observatories that will be trying to make such observations. Even today, there is the possibiity of detecting smaller worlds, down to Mars-size, around M-class red dwarfs, tiny stars something like Proxima Centauri or Barnard’s Star. You’ll find the systemic site at oklo.org to be a treasure trove of information on such ideas.
And yes, the technological limits we’re dealing with right now are why we tend to see large planets close in to their stars. These show up most dramatically in radial velocity searches and are thus the bulk of the detected exoplanets. Right now, according to Greg Laughlin at UC-Santa Cruz (and the oklo.org site), we probably could detect terrestrial-size worlds around Centauri A or B, assuming they exist, if we could devote enough telescope time to the job. It’s a matter of generating enough data for the computers to work with, and it’s quite time consuming!
I will go out on a limb and say that we’ll have the first detection of a small, rocky world something like the Earth within the next ten years, and I suspect it will actually be a good bit sooner. Keep your eye on space missions like Kepler and let’s hope it lives up to expectations.
Glad to have you here, by the way, and welcome!
WASP-1: A lithium- and metal-rich star with an oversized planet
Authors: H.C. Stempels, A. Collier Cameron, L. Hebb, B. Smalley, S. Frandsen
(Submitted on 11 May 2007)
Abstract: In this paper we present our results of a comprehensive spectroscopicanalysis of WASP-1, the host star to the exoplanet WASP-1b. We derive T_eff = 6110 +/- 45 K, log g = 4.28 +/- 0.15, and [M/H] = 0.23 +/- 0.08, and also a high abundance of lithium, log n(Li) = 2.91 +/- 0.05. These parameters suggests an age for the system of 1-3 Gyr and a stellar mass of 1.25-1.35 M_sun. This means that WASP-1 has properties very similar to those of HD 149026, the host star for the highest density planet yet detected.
Moreover, their planets orbit at comparable distances and receive comparable irradiating fluxes from their host stars. However, despite the similarity of WASP-1 with HD 149026, their planets have strongly different densities. This suggests that gas-giant planet density is not a simple function of host-star metallicity or of radiation environment at ages of ~2 Gyr.
Accepted for publication in MNRAS. 6 pages, 4 figures
From: Eric Stempels [view email]
[v1] Fri, 11 May 2007 15:59:43 GMT (318kb,D)
SuperWASP-N Extra-solar Planet Candidates Between 18hr
Astronomer’s role in new planets discovery
31 October 2007
A St Andrews researcher is part of the leading team of planet-hunting astronomers that have announced the discovery of three new planets today
(31 October 2007).
Professor Andrew Collier Cameron, of the University’s School of Physics & Astronomy, played an important role in the recent discovery of three planets said to be as big as Jupiter, and named WASP-3, WASP-4 and WASP-5.
Professor Cameron is a member of the Wide Area Search for Planets (WASP) team, which also includes astronomers from the University of Keele and Queen’s University Belfast. Using `super-cameras’ in South Africa and the Canary Islands that monitor millions of stars over the entire sky, the latest finding makes them the only team to have found transiting planets in both the Northern and Southern hemispheres. The team are already responsible for the discovery of two new planets named WASP-1 and WASP-2 last year.
Professor Cameron, who measured the sizes of the new extra-solar planets, said, “All three planets are similar to Jupiter, but are orbiting their stars so closely that their ‘year’ lasts less than two days. These are among the shortest orbital periods yet discovered. Being so close to their stars the surface temperatures of the planets will be more than 2000 degrees Celsius, so it is unlikely that life as we know it could survive there. But the finding of Jupiter-mass planets around other stars supports the idea that there are also many Earth-sized planets waiting to be discovered as astronomers’ technology improves.”
Over 200 extra-solar planets (those that orbit other stars, rather than our Sun) are currently known to astronomers. The three new planets were found as the WASP cameras detected small dips in the brightness of the host stars, caused when planets pass in front of, or transit, them. Studying such planets outside of our solar system allows scientists to investigate how planetary systems form.
Dr Coel Hellier of Keele University said, “When we see a transit we can deduce the size and mass of the planet and also what it is made of, so we can use these planets to study how solar systems form.”
WASP-4 and WASP-5 are the first planets discovered by the WASP project’s cameras in South Africa, and were confirmed by a collaboration with Swiss and French astronomers.
“These two are now the brightest transiting planets in the Southern hemisphere,” said Dr Hellier. WASP-3 meanwhile is the third planet that the team has found in the North, using the SuperWASP camera sited in the Canary Islands.
Dr Don Pollacco, of Queen’s University Belfast, said, “We are the only team to have found transiting planets in both the Northern and Southern hemispheres; for the first time we have both SuperWASP cameras running, giving complete coverage of the whole sky.”
The WASP project is the most ambitious project in the world designed to discover large planets. Funding for the project comes from the three universities and the Science and Technology Facility Council.
NOTE TO PICTURE EDITORS:
AN ARTIST’S IMPRESSION IS AVAILABLE FROM THE SCIENCE AND TECHNOLOGY FACILITIES COUNCIL PRESS OFFICE – CONTACTS BELOW.
NOTE TO EDITORS:
The discovery of WASP-3, WASP-4 and WASP-5 is being announced by the WASP project this week at an international conference on extrasolar planets in Suzhou (near Shanghai), China.
Professor Andrew Collier Cameron, University of St Andrews.
Tel: 01334 463147
Dr Don Pollacco, QUB, WASP Project Scientist
Tel: 02890 973512
Dr Coel Hellier, Keele University
Tel: 01782 584243
Gill Ormrod – Science and technology Facilities Council Press Office
Tel: 01793 442012. Mobile: 0781 8013509
Issued by the Press Office, University of St Andrews
Contact Gayle Cook, Press Officer on 01334 467227 / 462529, mobile 07900 050 103, or email email@example.com
Ref: Trio of new planets 311007
View the latest University press releases at http://www.st-andrews.ac.uk
WASP-3b: a strongly-irradiated transiting gas-giant planet
Authors: D. Pollacco, I. Skillen, A. Collier Cameron, B. Loeillet, H.C. Stempels, F. Bouchy, N.P. Gibson, L. Hebb, G. Hebrard, Y.C. Joshi, I. McDonald, B. Smalley, A.M.S. Smith, R.A. Street, S. Udry, R.G. West, D.M. Wilson, P.J. Wheatley, S. Aigrain, C.R. Benn, V.A. Bruce, D.J. Christian, W.I. Clarkson, B. Enoch, A. Evans, A.Fitzsimmons, C.A. Haswell, C. Hellier, S. Hickey, S.T. Hodgkin, K. Horne, M. Hrudkova, J. Irwin, S.R. Kane, F.P. Keenan, T.A. Lister, P. Maxted, M. Mayor, C. Moutou, A.J. Norton, J. P. Osborne, N. Parley, F. Pont, D. Queloz, R. Ryans, E. Simpson
(Submitted on 1 Nov 2007)
Abstract: We report the discovery of WASP-3b, the third transiting exoplanet to be discovered by the WASP and SOPHIE collaboration. WASP-3b transits its host star USNO-B1.0 1256-0285133 every 1.846834+-0.000002 days. Our high precision radial-velocity measurements present a variation with amplitude characteristic of a planetary-mass companion and in-phase with the light-curve. Adaptive optics imaging shows no evidence for nearby stellar companions, and line-bisector analysis excludes faint, unresolved binarity and stellar activity as the cause of the radial-velocity variations. We make a preliminary spectroscopic analysis of the host star finding it to have Teff = 6400+-100 K and log g = 4.25+-0.05 which suggests it is most likely an unevolved main sequence star of spectral type F7-8V. Our simultaneous modelling of the transit photometry and reflex motion of the host leads us to derive a mass of 1.76 +0.08 -0.14 M_J and radius 1.31 +0.07-0.14 R_J for WASP-3b. The proximity and relative temperature of the host star suggests that WASP-3b is one of the hottest exoplanets known, and thus has the potential to place stringent constraints on exoplanet atmospheric models.
Comments: 10 pages, 7 figures, 4 tables, submitted for publication in MNRAS
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0711.0126v1 [astro-ph]
From: Don Pollacco Dr [view email]
[v1] Thu, 1 Nov 2007 14:18:27 GMT (209kb)
SuperWASP-N Extra-solar Planet Candidates from Fields 06hr less than RA less than 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
(Submitted on 16 Nov 2007)
Abstract: 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 less than RA less than 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.
Comments: 13 pages, 6 figures, 4 tables, accepted for publication in MNRAS
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0711.2581v1 [astro-ph]
From: Stephen Kane [view email]
[v1] Fri, 16 Nov 2007 10:11:22 GMT (813kb)
WASP-4b: a 12th-magnitude transiting hot-Jupiter in the Southern hemisphere
Authors: D.M. Wilson, M. Gillon, C. Hellier, P.F.L. Maxted, F. Pepe, D. Queloz, D.R. Anderson, A. Collier Cameron, B. Smalley, T.A. Lister, S.J. Bentley, A. Blecha, D.J. Christian, B. Enoch, C.A. Haswell, L. Hebb, K. Horne, J. Irwin, Y.C. Joshi, M. Marmier, M. Mayor, N. Parley, D. Pollacco, F. Pont, R. Ryans, D. Segransan, I. Skillen, R.A. Street, S. Udry, R.G. West, P.J. Wheatley
(Submitted on 9 Jan 2008)
Abstract: We report the discovery of WASP-4b, a large transiting gas-giant planet with an orbital period of 1.34 days. This is the first planet to be discovered by the SuperWASP-South observatory and CORALIE collaboration and the first planet orbiting a star brighter than 16th magnitude to be discovered in the Southern hemisphere. A simultaneous fit to high-quality lightcurves and precision radial-velocity measurements leads to a planetary mass of 1.27 +/- 0.1 MJup and a planetary radius of 1.45 +/- 0.08 RJup. The host star is USNO-B1.0 0479-0948995, a G7V star of visual magnitude 12.5. As a result of the short orbital period, the predicted surface temperature of the planet is 1776 K, making it an ideal candidate for detections of the secondary eclipse at infrared wavelengths.
Comments: 7 pages incl. 4 figures. Accepted for publication in ApJL
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0801.1509v1 [astro-ph]
From: David Wilson Dr [view email]
[v1] Wed, 9 Jan 2008 21:03:19 GMT (102kb)
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
(Submitted on 10 Jan 2008)
Abstract: 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.
Comments: 4 pages, 4 figures, 4 tables, submitted to MNRAS Letters
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0801.1685v1 [astro-ph]
From: David Anderson [view email]
[v1] Thu, 10 Jan 2008 22:00:19 GMT (64kb)
SuperWASP are Super Planet-Finding Observatories
Written by Nancy Atkinson
The United Kingdom’s Wide Area Search for Planets, known as SuperWASP consists of two 8-camera robotic observatories that cover both hemispheres of the sky. In the past 6 months an international team of astronomers have used these unique observatories to discover 10 new extra-solar planets, making SuperWASP the most successful planet-hunting observatory in the world. The discovery of these planets was announced on April 1 by Dr. Don Pollacco of Queen’s University in Belfast at the Royal Astronomy Society’s National Astronomy Meeting in the UK.
All told, scientists have found more than 270 extrasolar planets since the the early 1990s. Most of these are detected through their gravitational influence on the star they orbit. As a planet orbits a star, it tugs the star back and forth. However, making these discoveries depends on looking at each star over a period of weeks or months, making the pace of discovery fairly slow.
But SuperWASP uses a different method. The two sets of cameras watch for events known as transits, where a planet passes directly in front of a star and blocks out some of the star’s light, so from the Earth the star temporarily appears a little fainter. The SuperWASP cameras work as robots, surveying a large area of the sky at once and each night astronomers have data from millions of stars that they can check for transits. The transit method also allows scientists to deduce the size and mass of each planet.
Full article here: