# Ten New Planets from SuperWASP

Results from the Wide Angle Search for Planets (SuperWASP) could hardly be better. In the last six months, astronomers using wide-field cameras in the Canary Islands and South Africa, working in conjunction with a battery of telescopes around the world, have identified ten new planets around other stars. The findings were announced yesterday at the Royal Astronomical Society’s national meeting in Belfast. We’re dealing with planetary transits here, planets moving across the face of their star as seen from Earth. 46 transiting worlds are known, of which SuperWASP has now found a solid fifteen.

Skymaps, coordinates and background information on all the SuperWASP planets can be found here. You’ll want to concentrate on WASP-6b through 15-b for the new ones, which include ‘hot Jupiters’ like WASP-12b (orbiting its primary, a G-class star 870 light years from Earth, in just over a day) and WASP-15b, one-half the mass of Jupiter, orbiting an F5 star a thousand light years away. The largest planet found was fully eight times the mass of Jupiter, again orbiting an F5 star in a scant 2.24 days.

Image: A schematic of the new discoveries. Click the diagram to get an enlarged image with further data. Credit: SuperWASP.

The robotic SuperWASP cameras sweep huge areas of the sky each night, offering astronomers data on millions of stars. Information on promising candidates is distributed to observatories ranging from the Nordic Optical Telescope on La Palma to the Swiss Euler Telescope in Chile and the Observatoire de Haute Provence in southern France. The Geneva Extrasolar Planet Search group then confirms potential planetary discovery through spectrographic analysis. The beauty of transits is that information about the size and mass of each planet can be deduced from the observations. With Kepler upcoming and COROT continuing its doughty work, the pace of transit discovery should only increase.

Addendum: Greg Laughlin (UC-SC) notes his annoyance with the SuperWASP announcement, particularly the lack of coordinates for the new planets and the inconsistency of some of the data on the relevant Web site. WASP-6b is reported, for example, to have a radius fifty percent that of Jupiter, and a mass of 1.3 Jovian masses. Says Laughlin on his systemic site:

That’s nuts! If the planet is so small, why is the transit so deep? And a 2200 K surface temperature for a 3.36d planet orbiting a G8 dwarf? Strange. Perhaps the radius and mass have been reversed? In addition, there are weird inconsistencies between the numbers quoted in the media diagram and in the tables. For example, the diagram pegs WASP-7 at 0.67 Jovian masses, whereas the table lists it at 0.86 Jovian masses. WASP-10 has a period of 5.44 days in the table and 3.093 days in the summary diagram. Putting out a press release without the support a refereed paper is never a very good idea, even when there’s a danger that another team will steal your thunder with an even larger batch of planets.

Comments on this entry are closed.

• ljk April 2, 2008, 9:29

The Monitor project: the search for transits in the open cluster NGC 2362

Authors: Adam A. Miller (1), Jonathan Irwin (2), Suzanne Aigrain (3), Simon Hodgkin (4), Leslie Hebb (5) (1. UC Berkeley, 2. CfA, 3. University of Exeter, 4. IoA – Cambridge, 5. University of St. Andrews)

(Submitted on 28 Mar 2008)

Abstract: We present the results of a systematic search for transiting planets in a ~5 Myr open cluster, NGC 2362. We observed ~1200 candidate cluster members, of which ~475 are believed to be genuine cluster members, for a total of ~100 hours. We identify 15 light curves with reductions in flux that pass all our detection criteria, and 6 of the candidates have occultation depths compatible with a planetary companion. The variability in these six light curves would require very large planets to reproduce the observed transit depth. If we assume that none of our candidates are in fact planets then we can place upper limits on the fraction of stars with hot Jupiters (HJs) in NGC 2362. We obtain 99% confidence upper limits of 0.22 and 0.70 on the fraction of stars with HJs (f_p) for 1-3 and 3-10 day orbits, respectively, assuming all HJs have a planetary radius of 1.5R_Jup. These upper limits represent observational constraints on the number of stars with HJs at an age <~10 Myr, when the vast majority of stars are thought to have lost their protoplanetary discs. Finally, we extend our results to the entire Monitor Project, a survey searching young, open clusters for planetary transits, and find that the survey as currently designed should be capable of placing upper limits on f_p near the observed values of f_p in the solar neighbourhood.

Comments: 17 pages, 11 figures, accepted to MNRAS

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0803.4004v1 [astro-ph]

Submission history

[v1] Fri, 28 Mar 2008 08:34:08 GMT (682kb)

http://arxiv.org/abs/0803.4004

• Freederick April 2, 2008, 13:40

If I read the data correctly, WASP-14 has a whopping 7.79 Jupiter masses, but its radius is 0.9 Jupiter’s radius. That works out to about 10 times the density of Jupiter, or more than twice the density of Earth. That’s no gas giant–that’s a ROCKY planet the size of Jupiter! Wow! The gravity on the surface (nearly 25 G’s) would flatten me into a pancake!

• devicerandom April 2, 2008, 14:00

That’s no gas giant–that’s a ROCKY planet the size of Jupiter! Wow! The gravity on the surface (nearly 25 G’s) would flatten me into a pancake!

I remember most gas giants have almost the same radius, despite large differences in mass (don’t remember the reason). The density could just mean that the core is particularly large and dense, but I doubt such a planet could be called “rocky”. The core is probably hidden under enormous layers of gases, supercritical gases and liquids, at tremendously high pressures.

• andy April 2, 2008, 14:05

Apparently the values are different in the image and on the website list: the radius has apparently been revised upwards to 1 Jupiter radius, which is perhaps slightly less problematic: a planet with a mass exceeding that of Jupiter gets more compressed in its core and so isn’t expected to be very much larger than Jupiter. (In fact the supermassive planet HAT-P-2b has similar parameters).

The really odd one is WASP-6b: the listed parameters are 1.30 Jupiter masses and a radius 0.5 times that of Jupiter. Another HD 149026b style super-Neptune? Or something weirder?

• andy April 2, 2008, 18:23

There’s an interesting post up at systemic about these planets – some of the numbers that are up at the SuperWASP website look somewhat suspicious, and different values are given in different places… maybe WASP-6b isn’t such an unusual planet after all.

• James M. Essig April 3, 2008, 4:22

Hi ljk, Freederick, devicerandom, and andy;

So far we have discovered on the order of a few hundred extrasolar planets. With improved techniques, the number is bound to quicky grow to over a thousand planets over the next several years.

I was just talking with my brother John 2 days ago who also has an interest in space and he made a rather profound comment, to which I am not sure if he quoted someone else or thought of it himself, to the effect of “What we need is a program like that of the pioneering days of pre-colonial North America and later in colonial North America that entailed reaching out to the seven continents, but now instead, we need to reach out to, explore, and perhaps colonize the planets around 7 extra-solar star systems”.

We are all very much familiar with the beautiful mountainous landscapes within North America, Europe, the Ural Mountains in Asia, the Himilayas especially the great Mount Everest, the wonderful mountains in Africa, and the various huge volcanoes within the Pacific Rim as well as the numerous beaches and other aquatic environments on our planet. Just imagine the wide variety of geological, topographical, and oceanic environments on any extra-solar terrestrial worlds. We know as a fact that any terrestrial planets around other stars are by definition going to have such features even if no life exist on them.

If some of these extrasolar terrestrial planets have animal life, we can just imagine what these animals might look like. I can imagine an issue of National Geographic Magazine in the late 21st Century having interactive full color inserts showing migrating herds of herbavores on extrasolar planets and perhaps even the bringing back to Earth of exotic animal species for humane study and caretaking by late 21st Century and early 22nd Century exo-zoolologists. The really odd thing is, if these animals prove sufficiently docile, safe, or trainable, we might even domesticate them and keep them as pets. I would definately settle for a cute cuddly ET kitty-cat.

Thanks;

Jim

• Adam April 3, 2008, 6:21

Hi All

FYI but under about ~ 10 billion years of age planets more massive than Jupiter in normal conditions have roughly the same radii – if made from the same mix of hydrogen/helium. Internal heat keeps the heavier planets puffed up, else every planet heavier than ~ 3.24 Jupiter masses would be smaller than Jupiter, due to an increasing fraction of degenerate matter in the core.

As for rocky planets, the maximum size of a planet made of pure SiO2 is about 3 Earth radii (Jupiter being 11.2) – this is also due to the onset of degeneracy in the planet’s core past a certain mass. A very HOT silicate planet could be bigger, supported by gas(!) pressure, but it obviously wouldn’t be solid.

One caveat is that a planet could spin very rapidly and be larger (in one or two axes) than that limit. But past a certain angular momentum and the whole lot disrupts, losing mass from the equator until equilibrium is reached again.

• Administrator April 3, 2008, 8:31

Re the SuperWASP planets, I’ve linked to the systemic post that andy mentioned above, and added a quote from it to the main entry. Apparently the inconsistencies in some of these data are begging for revision.

• andy April 3, 2008, 11:07

Re the radii of planets of different compositions, this paper has a whole bunch of different mass/radius relationships for various compositions of planet. A terrestrial planet of mass 7.79 Jupiter masses has a radius of about 3.5 Earth radii (=0.3 Jupiter radii) if it doesn’t have an iron core, which would perhaps be somewhat unlikely.

• Dave Moore April 3, 2008, 14:15

On a slightly different note, I hope there is an ongoing program of high precision monitoring of superWASP 11 and 15. Both those systems appear to be almost edge on to our line of sight so there’d be a good chance that planets further out in the system would also eclipse their primary.

Dave.

• Thomas April 4, 2008, 10:31

@Dave Moore,
Not necessarily. Look at our own solar system. The planets aren’t very coplanar. Especially the inner terrestrial planets, where inclinations can be different from each other by several degrees. I don’t think there’s any reason to assume that an extrasolar planet in an i=90 degree orbit would have any companions that also transit.

I think that the chances of detecting a second transiting planet are just as high for an i=90 exoplanet, as for an i -88 exoplanet.

• ljk April 9, 2008, 8:44

Predicting the Yields of Photometric Surveys for Transiting Extrasolar Planets

Authors: Thomas G. Beatty, B. Scott Gaudi

(Submitted on 7 Apr 2008)

Abstract: We develop a method for predicting the yield of transiting planets from a photometric survey given the parameters of the survey (nights observed, bandpass, exposure time, telescope aperture, locations of the target fields, observational conditions, and detector characteristics), as well as the underlying planet properties (frequency, period and radius distributions).

Using our updated understanding of transit surveys provided by the experiences of the survey teams, we account for those factors that have proven to have the greatest effect on the survey yields. Specifically, we include the effects of the surveys’ window functions, adopt revised estimates of the giant planet frequency, account for the number and distribution of main-sequence stars in the survey fields, and include the effects of Galactic structure and interstellar extinction. We approximate the detectability of a planetary transit using a signal-to-noise ratio (S/N) formulation.

We argue that our choice of detection criterion is the most uncertain input to our predictions, and has the largest effect on the resulting planet yield. Thus drawing robust inferences about the frequency of planets from transit surveys will require that the survey teams impose and report objective, systematic, and quantifiable detection criteria. Nevertheless, with reasonable choices for the minimum S/N, we calculate yields that are generally lower, more accurate, and more realistic than previous predictions.

As examples, we apply our method to the Trans-Atlantic Exoplanet Survey, the XO survey, and the {\it Kepler} mission. We discuss red noise and its possible effects on planetary detections. We conclude with estimates of the expected detection rates for future wide-angle synoptic surveys.

Comments: 23 pages, 16 figures, submitted to ApJ

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0804.1150v1 [astro-ph]

Submission history

From: Thomas Beatty [view email]

[v1] Mon, 7 Apr 2008 21:18:59 GMT (285kb)

http://arxiv.org/abs/0804.1150

• ljk May 7, 2008, 22:46

ELODIE metallicity-biased search for transiting Hot Jupiters V. An intermediate-period Jovian planet orbiting HD45652

Authors: N. C. Santos, S. Udry, F. Bouchy, R. Da Silva, B. Loeillet, M. Mayor, C. Moutou, F. Pont, D. Queloz, S. Zucker, D. Naef, F. Pepe, D. Segransan, I. Boisse, X. Bonfils, X. Delfosse, M. Desort, T. Forveille, G. Hebrard, A.-M. Lagrange, C. Lovis, C. Perrier, A. Vidal-Madjar

(Submitted on 7 May 2008)

Abstract: In this paper we present the detection of a 0.47 Jupiter Mass planet in a 44-day period eccentric trajectory (e=0.39) orbiting the metal-rich star HD45652. This planet, the seventh giant planet discovered in the context of the ELODIE metallicity-biased planet search program, is also confirmed using higher precision radial-velocities obtained with the CORALIE and SOPHIE spectrographs. The orbital period of HD45652b places it in the middle of the “gap” in the period distribution of extra-solar planets.

Comments: 5 pages, 4 figures, Astronomy & Astrophysics, in press

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0805.1019v1 [astro-ph]

Submission history

From: Nuno C. Santos [view email]

[v1] Wed, 7 May 2008 16:43:04 GMT (56kb)

http://arxiv.org/abs/0805.1019

• ljk May 9, 2008, 10:02

Planets by the Dozens

NASA Science News for May 8, 2008

A NASA-supported sky survey set to begin in 2008 could dramatically increase the number of known planets outside our solar system.

FULL STORY at

• ljk May 20, 2008, 11:53

WASP-7: The brightest transiting-exoplanet system in the Southern hemisphere

Authors: Coel Hellier, D.R. Anderson, M. Gillon, T.A. Lister, P.F.L. Maxted, D. Queloz, B. Smalley, A. Triaud, R.G. West, D.M. Wilson, K. Alsubai, S.J. Bentley, A. Collier Cameron, L. Hebb, K. Horne, J. Irwin, S.R. Kane, M. Mayor, F. Pepe, D. Pollacco, I. Skillen, S. Udry, P.J. Wheatley, D.J. Christian, R. Enoch, C.A. Haswell, Y.C. Joshi, A.J. Norton, R. Ryans, R.A. Street, I. Todd

(Submitted on 16 May 2008)

Abstract: We report that a Jupiter-mass planet, WASP-7b, transits the V = 9.5 star HD197286 every 4.95 d. This is the brightest discovery from the WASP-South transit survey and the brightest transiting-exoplanet system in the Southern hemisphere. WASP-7b is among the densest of the known Jupiter-mass planets, suggesting that it has a massive core. The planet mass is 0.96 M_Jup, the radius 0.915 R_Jup, and the density 1.26 rho_Jup.

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0805.2600v1 [astro-ph]

Submission history

From: Coel Hellier [view email]

[v1] Fri, 16 May 2008 18:47:46 GMT (85kb)

http://arxiv.org/abs/0805.2600

• ljk June 11, 2008, 23:10

WASP-14b: A 7.7 Mjup transiting exoplanet in an eccentric orbit

Authors: Y. C. Joshi, D. Pollacco, A. Collier Cameron, I. Skillen, E. Simpson, I. Steele, R. A. Street, H. C. Stempels, F. Bouchy, D. J. Christian, N. P. Gibson, L. Hebb, G. Hebrard, F. P. Keenan, B. Loeillet, J. Meaburn, C. Moutou, B. Smalley, I. Todd, R. G. West, D. Anderson, S. Bentley, B. Enoch, C. A. Haswell, C. Hellier, K. Horne, J. Irwin, T. A. Lister, I. McDonald, P. Maxted, M. Mayor, A. J. Norton, N. Parley, C. Perrier, F. Pont, D. Queloz, R. Ryans, A. M. S. Smith, S. Udry, P. J. Wheatley, D. M. Wilson

(Submitted on 9 Jun 2008)

Abstract: We report the discovery of a 7.7 Mjup exoplanet WASP-14b, one of the most massive transiting exoplanets observed to date. The planet orbits the tenth-magnitude F5V star USNO-B1 11118-0262485 with a period of 2.243756 days and orbital eccentricity e = 0.095. A simultaneous fit of the transit light curve and radial velocity measurements yields a planetary mass of 7.7(+0.4)(-0.7) Mjup and a radius of 1.26(+0.08)(-0.06) Rjup.

This leads to a mean density of about 5.1 gcm^{-3} making it one of the densest transiting exoplanets yet found at an orbital period less than 3 days.

We estimate this system to be at a distance of 160+/-20 pc. Spectral analysis of the host star reveals a temperature of 6475+/-100 K, log g = 4.33 cms$^{-2}$ and v sin i = 4.9+/-1.0 km s$^{-1}$, and also a high lithium abundance, log N(Li) = 2.84+/-0.05. The stellar density, effective temperature and rotation rate suggest an age for the system of about 0.5–1.0 Gyr.

Comments: 10 pages, 8 figures, 3 tables, submitted to MNRAS

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0806.1478v1 [astro-ph]

Submission history

From: Yogesh Joshi [view email]

[v1] Mon, 9 Jun 2008 15:44:33 GMT (261kb)

http://arxiv.org/abs/0806.1478

• ljk June 11, 2008, 23:11

WASP-10b: a 3M_J, eccentric transiting gas-giant planet

Authors: D.J. Christian, N.P. Gibson, E.K. Simpson, R.A. Street, I. Skillen, D. Pollacco, A. Collier Cameron, H.C. Stempels, C.A. Haswell, K. Horne, Y.C. Joshi, F.P. Keenan, D.R. Anderson, S. Bentley, F. Bouchy, W.I. Clarkson, B. Enoch, L. Hebb, G. Hébrard, C. Hellier, J. Irwin, S.R. Kane, T.A. Lister, B. Loeillet, P. Maxted, M. Mayor, I. McDonald, C. Moutou, A.J. Norton, N. Parley, F. Pont, D. Queloz, R. Ryans, B. Smalley, A.M.S. Smith, I. Todd, S. Udry, R.G. West, P.J. Wheatley, D.M. Wilson

(Submitted on 9 Jun 2008)

Abstract: We report the discovery of WASP-10b, a new transiting extrasolar planet (ESP) discovered by the WASP Consortium and confirmed using NOT FIES and SOPHIE radial velocity data. A 3.09 day period, 33 mmag transit depth, and 2.36 hour duration are derived for WASP-10b using WASP and high precision photometric observations. Simultaneous fitting to the photometric and radial velocity data using a Markov-chain Monte Carlo procedure leads to a planet radius of 1.29R_J, a mass of 3.06M_J and eccentricity of $\approx$0.06.

WASP-10b is one of the more massive transiting ESPs, and we compare its characteristics to the current sample of transiting ESP, where there is currently little information for masses greater than ~2M_J and non-zero eccentricities. WASP-10’s host star, GSC 2752-00114 (USNO-B1.0 1214-0586164) is among the fainter stars in the WASP sample, with V=12.7 and a spectral type of K5. This result shows promise for future late-type dwarf star surveys.

Comments: 8 Pages, 5 Figures, 3 Tables, submitted to MNRAS

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0806.1482v1 [astro-ph]

Submission history

From: Damian Christian [view email]

[v1] Mon, 9 Jun 2008 15:54:11 GMT (130kb)

http://arxiv.org/abs/0806.1482

• ljk January 30, 2009, 0:35

Discovery and characterization of WASP-6b, an inflated sub-Jupiter mass planet transiting a solar-type star

Authors: M. Gillon, D. R. Anderson, A. H. M. J. Triaud, C. Hellier, P. F. L. Maxted, D. Pollaco, D. Queloz, B. Smalley, R. G. West, D. M. Wilson, S. J. Bentley, A. Collier Cameron, B. Enoch, L. Hebb, K. Horne, J. Irwin, Y. C. Joshi, T. A. Lister, M. Mayor, F. Pepe, N. Parley, D. Segransan, S. Udry, P. J. Wheatley

(Submitted on 29 Jan 2009)

Abstract: We report the discovery of WASP-6b, an inflated sub-Jupiter mass planet transiting every 3.3610060 +0.0000022-0.0000035 days a mildly metal-poor solar-type star of magnitude V=11.9. A combined analysis of the WASP photometry, high-precision followup transit photometry and radial velocities yield a planetary mass M_p = 0.503 +0.019-0.038 M_jup and radius R_p = 1.224 +0.051-0.052 R_jup, resulting in a density rho_p = 0.27 +-0.05 rho_jup. The mass and radius for the host star are M_s = 0.88 +0.05-0.08 M_sun and R_s = 0.870 +0.025-0.036 R_sun.

The non-zero orbital eccentricity e = 0.054 +0.018-0.015 that we measure suggests that the planet underwent a massive tidal heating ~1 Gyr ago that could have contributed to its inflated radius. High-precision radial velocities obtained during a transit allow us to measure a sky-projected angle between the stellar spin and orbital axis Beta = 11 +14-18 deg.

In addition to similar published measurements, this result favors a dominant migration mechanism based on tidal interactions with a protoplanetary disk.

Comments: submitted to A&A, 10 pages, 6 figures, 5 tables

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:0901.4705v1 [astro-ph.EP]

Submission history

From: Michael Gillon [view email]

[v1] Thu, 29 Jan 2009 15:24:20 GMT (277kb)

http://arxiv.org/abs/0901.4705