SuperWASP Results

The oklo blog reports that there was some initial misconception about the transit ephemeris on WASP-12 b, causing some initial excitement over the possibility of severe transit timing variations. Turned out the ephemeris was just misprinted.

http://oklo.org/?p=311

Sort-of interesting.

I wonder if the next batch of SuperWASP planets will get announced before the papers on the April 1st batch become public.

From papers about SuperWASP candidates in several sky fields, it seems there are lots of transiting object to be confirmed as planetay either low-mass stellar. Especially considering hot jupiters radii can reach 1.7 times the size of Jupiter; several neglected candidates may be revisited...

A paper on WASP-4

The Transit Light Curve Project. XI. Submillimagnitude Photometry of Two Transits of the Bloated Planet WASP-4b
http://arxiv.org/abs/0901.4346

Abstract wrote:

We present photometry of two transits of the giant planet WASP-4b with a photometric precision of 400-800 parts per million and a time sampling of 25-40 seconds. The two midtransit times are determined to within 6 seconds. Together with previously published times, the data are consistent with a constant orbital period, giving no compelling evidence for period variations that would be produced by a satellite or additional planets. Analysis of the new photometry, in combination with stellar-evolutionary modeling, gives a planetary mass and radius of 1.237 +/- 0.064 M_jup and 1.365 +/- 0.021 R_jup. The planet is 15% larger than expected based on previously published models of solar-composition giant planets. With data of the quality presented here, the detection of transits of a "super-Earth" of radius 1.75 R_earth would have been possible.

The WASP-6 paper is out.

Discovery and characterization of WASP-6b, an inflated sub-Jupiter mass planet transiting a solar-type star
http://arxiv.org/abs/0901.4705

Abstract wrote:

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.

The paper tells of the host star, but ... I can't find it in SIMBAD . Can anyone find it?

It must be added. Maybe tomorrow you'll find the host star at SIMBAD.

The paper claims that there is no evidence for a second planet.
Here's a page that references the Neptune that Borislav posted.
http://archive.eso.org/wdb/wdb/eso/eso_archive_main/query?dp_id=HARPS.2008-10-23T02:46:24.363&format=SexaHour&tab_stat_plot=on&aladin_colour=aladin_instrument

There is a program with that name (search for the program ID and drop the (E) part)... interesting, but concrete results might take a while.

However it's interesting that WASP-6b just looks like 51 Pegasi b. Roughly same mass, orbital separations.
I wonder why no transit has been detected for 51 Peg, being as nearby as HD 189733.

Transits depend on the orientation of the orbit, not the proximity of the star to Earth. Probability of 51 Peg b transit is about 11% assuming random distribution of orbital orientation, and not taking into account any negative results from transit searches.

Sirius_Alpha wrote:

The paper tells of the host star, but ... I can't find it in SIMBAD . Can anyone find it?

SIMBAD doesn't know the designations WASP-7 or WASP-12 either. It is possible to bring up the information for WASP-7 by using the designation HD 197286, but there are no references listed (despite the paper having been published)... WASP-6 and WASP-12 on the other hand are totally missing.

Edit: Hmm... looks like WASP-7 is now recognised.

Here's the WASP-15 paper.

The low density transiting exoplanet WASP-15b
http://arxiv.org/abs/0902.2651

Abstract wrote:

We report the discovery of a low-density exoplanet transiting an 11th magnitude star in the Southern hemisphere. WASP-15b, which orbits its host star with a period P=3.7520656+-0.0000028d has a mass M_p=0.542+-0.050M_J and radius R_p=1.428+-0.077R_J, and is therefore the one of least dense transiting exoplanets so far discovered (rho_p=0.247+-0.035g cm^-3). An analysis of the spectrum of the host star shows it to be of spectral type around F5, with an effective temperature T_eff=6300+-100K and [Fe/H]=-0.17+-0.11.

WASP-12 has been added too and seems to be placed in Auriga field, whereas both WASP-6 and 15 should be located in Centaurus.

I believe.

I've found an abstract about such a WASP-17 in ADS service:

WASP-17 - testing the paradigm of pM/pL class planets

Quote :

The structure, formation and fate of hot Jupiter exoplanets is governed by the properties of their atmospheres. There is an urgent need for for strong observational constraints to guide the development of model atmospheres for hot Jupiters. WASP-17b is a newly discovered transiting hot Jupiter exoplanet. It has the lowest density of any transiting hot Jupiter discovered to-date. The host star, WASP-17, is a bright (VD11.6) F6V star. This combination of factors make WASP-17 a key object for testing the current paradigm in which hot pM class planets have stratospheres and cooler pL class planets do not. We will use Spitzer to observe the secondary eclipse of the planet by its host star at 3.6um and 4.5um, and use these data to measure the brightness temperature at these wavelenghs. In the current paradigm, this pM class planet should show evidence of a stratosphere from the ratio of the brightness temperatures at these wavelengths. We will also use transmission spectroscopy to determine independently whether WASP-17b has a stratoshere. VLT time to obtain the required spectroscopy has already been approved. WASP-17 is currently the only pM class planet apart from HD209458 for which the results from the two methods can be compared. The Spitzer data that we will obtain for WASP-17 are essential for us to fully understand exploit the Spitzer observations of exoplanets that will be obtained in the warm mission.

And hints for WASP-18 and WASP-19 (and 16?). No full paper for both.

Lightcurves of two newly discovered ultra-short period planets

Quote :

The structure, formation and fate of hot Jupiter exoplanets is governed by the properties of their atmospheres. There is an urgent need for for strong observational constraints to guide the development of model atmospheres for hot Jupiters. One of the most powerful techniques for probing hot Jupiter atmospheres is to observe the small variation in infrared flux through the orbital cycle for transiting hot Jupiters. These observations can be converted into a map of the temperature distribution around the planet. This gives us a direct measurement of the way heat is redistributed through the planet's atmosphere. The processes that redistribute heat from the day-side to the night-side in these tidally locked planets are very poorly understood. This limits our ability to interpret observations of hot Jupiters obtained with Spitzer and other instruments. Phase variations are small so they have only been succesfully observed in a handful of hot Jupiter systems. There are, as yet, no detections of the phase variation in any transiting hot-Jupiters with atmospheres hot enough to have a stratosphere, and only one (HD189733) for a cooler transiting hot Jupiter. We will observe the lightcurves of WASP-18 and WASP-19, to newly discovered ultra-short period planets (P<1day). These are key objects for understanding heat redistribution in hot Jupiters because the irradiation of their day-side is so extreme.

I've submitted this entry also in Unconfirmed Planet Catalogue thread.

http://www.astronomynow.com/nam09/2009/04/transiting-planets-galore.html

Quote :

Transiting planets galore!
By Keith Cooper on April 21, 2009 2:34 PM | No Comments
One of the most exciting presentations of NAM so far (at least to my mind), has been Super-WASP, which gave us a sneak peak at several new transiting planets. Super-WASP consists of two observatories built with 'off the shelf' CCD cameras that are capable of spotting the tiny dip in light as a planet moves in front of, or transits, its star. They're based one in each hemisphere, and the presentation today was about planets discovered with Super-WASP South, which has been operating since March 2006. What I hadn't realised is that of the 58 known transiting planets, a third of them have been discovered by Super-WASP! The latest ones are all gas giants, all with short orbits around their stars. The longest orbital period observed was just a shade under five days, and this planet (WASP-20) was also the smallest of the latest batch of planets at 0.3 times the mass of Jupiter. Conversely, the most massive, WASP 18, was a whopping 10 times the mass of Jupiter, while another (WASP-17) is quite possibly the most bloated, swollen planet observed so far. Explaining why it is so bloated is still a bit of a mystery, but this is what makes exoplanet research so fascinating.

WASP-18 a very massive transiting planet with 10 Jupiter masses

Finally, the WASP-13 paper.

The 0.5M$_J$ transiting exoplanet WASP-13b
http://arxiv.org/abs/0905.3115

Abstract wrote:

We report the discovery of WASP-13b, a low-mass $ M_p = 0.46 ^{+ 0.06}_{- 0.05} M_J$ transiting exoplanet with an orbital period of $4.35298 \pm 0.00004$ days. The transit has a depth of 9 mmag, and although our follow-up photometry does not allow us to constrain the impact parameter well ($0 < b < 0.46$), with radius in the range $R_p \sim 1.06 - 1.21 R_J$ the location of WASP-13b in the mass-radius plane is nevertheless consistent with H/He-dominated, irradiated, low core mass and core-free theoretical models. The G1V host star is similar to the Sun in mass (M$_{*} = 1.03^{+0.11}_ {- 0.09} M_{\odot}$) and metallicity ([M/H]=$0.0\pm0.2$), but is possibly older ($8.5^{+ 5.5}_{- 4.9}$ Gyr).

A Third Exoplanetary System with Misaligned Orbital and Stellar Spin Axes
http://arxiv.org/abs/0907.5204

Abstract wrote:

We present evidence that the WASP-14 exoplanetary system has misaligned orbital and stellar-rotational axes, with an angle lambda = 33.1 +/- 7.4 deg between their sky projections. The evidence is based on spectroscopic observations of the Rossiter-McLaughlin effect as well as new photometric observations. WASP-14 is now the third system known to have a significant spin-orbit misalignment, and all three systems have "super-Jupiter" planets (M_P > 3 Mjup) and eccentric orbits. This finding suggests that the migration and subsequent orbital evolution of massive, eccentric exoplanets is somehow different from that of less massive close-in Jupiters, the majority of which have well-aligned orbits.

WASP-16b - non-inflated hot Jupiter.

And now there are WASP-19 and 20 left to be released.
Actually also 8 and 9.

I think it is time I updated the WASP planets publication status from upthread. Since then, many of the planets have been published in refereed journals, and we've now got WASP-16b. For completeness I've also put WASP-1b to 5b in there as well.

WASP-1b	Published March 2007
WASP-2b	Published March 2007
WASP-3b	Published April 2008
WASP-4b	Published March 2008
WASP-5b	Published June 2008
WASP-6b	Published July 2009
WASP-7b	Published January 2009
WASP-8b	Not yet identified
WASP-9b	Not yet identified
WASP-10b	Published December 2008
WASP-11b/HAT-P-10b	Published May 2009 (HAT-P-10b) Published July 2009 (WASP-11b)
WASP-12b	Published March 2009
WASP-13b	Published July 2009
WASP-14b	Published December 2008
WASP-15b	Published June 2009
WASP-16b	arXiv

WASP-17 looks like it might be an interesting planet.

WASP-17b: an ultra-low density planet in a probable retrograde orbit
http://arxiv.org/abs/0908.1553

Abstract wrote:

We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses but 1.5-2 Jupiter radii, giving a density of 6-14 per cent that of Jupiter. WASP-17b is in a 3.7-day orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a retrograde orbit (lambda ~ -150 deg), indicative of a violent history involving planet-planet or planet-star scattering.
WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularisation of an eccentric orbit, such as the highly eccentric orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.

Er... wow. Raises possibilities for counter-rotating planets, huge mutual inclinations, etc.

(Not that there seems to be any evidence for additional planets there at the moment)

Some (normally clogged) news outlets have the story up now.