HATnet Results

Title: HAT-P-9b: A Low Density Planet Transiting a Moderately Faint F star

Another transiting hot Jupiter...

p.s. the 10 character lower limit on topic titles is somewhat annoying...

Lazarus wrote:

p.s. the 10 character lower limit on topic titles is somewhat annoying...

Changed to 1.

Good news, I suppose. The more the planets the better, even if they're hot Jupiters, lol. Another point on the radius-(some other parameter) chart.

It seems we've HAT-P-8b missing...

Somehow I feel it'll show up eventually... it can be that the paper for this one was ready earlier.

HATNet Field G205: Follow-Up Observations of 28 Transiting-Planet candidates and Confirmation of the Planet HAT-P-8b
http://arxiv.org/abs/0812.1161

Abstract wrote:

We report the identification of 32 transiting-planet candidates in HATNet field G205. We describe the procedures that we have used to follow up these candidates with spectroscopic and photometric observations, and we present a status report on our interpretation of the 28 candidates for which we have follow-up observations. Eight are eclipsing binaries with orbital solutions whose periods are consistent with their photometric ephemerides; two of these spectroscopic orbits are singled-lined and six are double-lined. For one of the candidates, a nearby but fainter eclipsing binary proved to be the source for the HATNet light curve, due to blending in the HATNet images. Four of the candidates were found to be rotating more rapidly than vsini = 50 km/s and were not pursued further. Thirteen of the candidates showed no significant velocity variation at the level of 0.5 to 1.0 km/s . Seven of these were eventually withdrawn as photometric false alarms based on an independent reanalysis using more sophisticated tools. Of the remaining six, one was put aside because a close visual companion proved to be a spectroscopic binary, and two were not followed up because the host stars were judged to be too large. Two of the remaining candidates are members of a visual binary, one of which was previously confirmed as the first HATNet transiting planet, HAT-P-1b. In this paper we confirm that the last of this set of candidates is also a a transiting planet, which we designate HAT-P-8b, with mass Mp = 1.52 +/- 0.18/0.16 Mjup, radius Rp = 1.50 +/- 0.08/0.06 Rjup, and photometric period P = 3.076320 +/- 0.000004 days. HAT-P-8b has an inflated radius for its mass, and a large mass for its period. The host star is a solar-metallicity F dwarf, with mass M* = 1.28 +/- 0.04 Msun and Rp = 1.58 +/- 0.08/0.06 Rsun.

HAT-P-11b: A Super-Neptune Planet Transiting a Bright K Star in the Kepler Field
http://arxiv.org/abs/0901.0282

Abstract wrote:

We report on the discovery of HAT-P-11b, the smallest radius transiting extrasolar planet (TEP), and the first hot Neptune discovered to date by transit searches. HAT-P-11b orbits the bright (V=9.59) and metal rich ([Fe=H] = +0.31 +/- 0.05) K4 dwarf star GSC 03561-02092 with P = 4.8878162 +/- 0.0000071 days and produces a transit signal with depth of 4.2 mmag; the shallowest found by transit searches that is due to a confirmed planet. We present a global analysis of the available photometric and radial-velocity data that result in stellar and planetary parameters, with simultaneous treatment of systematic variations. The planet, like its near-twin GJ 436b, is somewhat larger than Neptune (17 Mearth, 3.8 Rearth) both in mass Mp = 0.081 +/- 0.009 MJup (25.8 +/- 2.9 Mearth) and radius Rp = 0.422 +/- 0.014 RJup (4.73 +/- 0.16 Rearth). HAT-P-11b orbits in an eccentric orbit with e = 0.198 +/- 0.046 and omega = 355.2 +/- 17.3 deg, causing a reflex motion of its parent star with amplitude 11.6 +/- 1.2 m/s, a challenging detection due to the high level of chromospheric activity of the parent star. Our ephemeris for the transit events is Tc = 2454605.89132 +/- 0.00032 (BJD), with duration 0.0957 +/- 0.0012 d, and secondary eclipse epoch of 2454608.96 +/- 0.15 d (BJD). The basic stellar parameters of the host star are M* = 0.809 +/- ^0.020_0.027 Msun, R* = 0.752 +/- 0.021 Rsun and Teff = 4780 +/- 50 K. Importantly, HAT-P-11 will lie on one of the detectors of the forthcoming Kepler mission; this should make possible fruitful investigations of the detailed physical characteristic of both the planet and its parent star at unprecedented precision.

Very nice find! Very nice!

(Do you guys mind if I merge all the HAT planet threads into one for organisation? Like with the WASP threads?)

The latest oklo.org anagram decrypts to "HAT found a Neptune"...

Lazarus wrote:

The latest oklo.org anagram decrypts to...

Fascinating!

This is great, the first Neptune from a transit search survey! I must admit, the anagram is rather cryptic. I wonder how, or even if, it is related to the earlier anagram posted on Oklo.org. I also find Greg Laughlin's posted reply rather ... cryptic. Why turn the comments off? The paper is publicly available (though it wasn't last night, when Mr. Laughlin claims to have recieved the e-mail).

The email makes sense to me.

A smaller cousin of a jupiter sized planet orbiting very close to it's star....it is oddly like the story of phaeton no?

More about this system at systemic

-- regarding merging the threads, I'd agree for the hot Jupiter-type planets... is there enough interest in transiting Neptunes to warrant separate threads?

thats a pretty awsome discovery

Got to wonder how massive Neptune-type planets can get. HD 149026b might be an indication that you can get them up to Saturn mass or so (though despite sometimes being termed a super-Neptune, HD 149026b has a significantly lower metals to gas ratio than the ice giants in our solar system, GJ 436b or HAT-P-11b).

Anyone want to guess whether 55 Cancri c and f are more Neptune-like or more Jupiter-like, or something else?

I'm guessing 55 Cnc c and f are both Jovian.

Such a wonderful planet to open the new year!

Moreover it looks a "GJ 436 b" analogue.

Least massive H/He dominated gas giant planet. Approx. 70 Earth-Masses, right in the middle of the Neptune-Saturn desert.

http://exoplanet.eu/planet.php?p1=HAT-P-12&p2=b

Neptune-Saturn desert, what is it?? I heard only about the desert of the brown dwarfs

When planets form, you get a handful of what are called "oligarchs". These are the largest pebbles that become massive enough to accrete a lot of matter. They undergo rapid growth. Oligarchs out in the outer region of a solar system grow quickly and accumulate a bunch of gas, and go on to become gas giants. Neptune-type planets form later, when there isn't much material left over.

This sort of divides the oligarchs into small planets (sub-Jovian, what we call Neptunes and Super Earths), and big planets (Jovian). There aren't expected to be many planets between the two domains.

Once you hand out all the big food to the hungry children, you've only got crumbs to give away. Some kids will get a whole slice of bread, the rest will get crumbs.

I'm surprised by the radius of this planet, especially given the mass.

Therefore the Neptune-Saturn desert is not a forbidden orbital space (as for the brown dwarfs) but an interval of masses prohibited.Isn't it?

Yeah, there's just a paucity of planets in this mass region, but not a deep void as we find with short-period brown dwarfs.

Follow up observations yield a slightly larger radius.

Follow-up Observations of the Neptune Mass Transiting Extrasolar Planet Hat-P-11b
http://arxiv.org/abs/0905.1114

Abstract wrote:

We have confirmed the existence of the transiting super Neptune extrasolar planet HAT-P-11b. On May 1, 2009 UT the transit of Hat-P-11b was detected at the University of Arizona's 1.55m Kuiper Telescope with 1.7 millimag rms accuracy. We find a central transit time of Tc = 2454952.92534+/-0.00060 BJD; this transit occurred 80+/-73 seconds sooner than previous measurements (71 orbits in the past) would have predicted. Hence, our transit timing rules out large deviations from the ephemeris of Bakos et al. (2009). We measure a slightly larger planetary radius of Rp=0.452+/-0.020 R_Jup (5.07+/-0.22 R_earth) compared to Bakos and co-workers' value of 0.422+/-0.014 R_Jup (4.73+/-0.16 R_earth). Our values confirm that Hat-P-11b is very similar to GJ 436b (the only other known transiting super Neptune) in radius and other bulk properties.

HAT-P-13b,c: a transiting hot Jupiter with a massive outer companion on an eccentric orbit

The "tastiest" multiplanet system [with transiting primary planet] ever found. Hot Jupiter + Outer SuperJovian/Brown dwarf

Quote :

We report on the discovery of a planetary system with a close-in transiting hot Jupiter on a near circular orbit and a massive outer planet on a highly eccentric orbit. The inner planet, HAT-P-13b, transits the bright V=10.622 G4 dwarf star GSC 3416-00543 every P = 2.916260 pm 0.000010 days, with transit epoch Tc = 2454779.92979 pm 0.00038 (BJD) and duration 0.1345 pm 0.0017 d. The outer planet, HAT-P-13c orbits the star with P2 = 428.5 pm 3.0 days and nominal transit center (assuming zero impact parameter) of T2c = 2454870.4 pm 1.8 (BJD) or time of periastron passage T2,peri= 2454890.05 pm 0.48 (BJD). Transits of the outer planet have not been observed, and may not be present. The host star has a mass of 1.22+0.05-0.10Msun, radius of 1.56 pm 0.08 Rsun, effective temperature 5638 pm 90K, and is rather metal rich with [Fe/H] = +0.43pm0.08. The inner planetary companion has a mass of 0.851+/0.029-/0.046 Mjup, and radius of 1.280pm0.079 Rjup yielding a mean density of 0.499+/0.103-/0.069 gcm-3 . The outer companion has m_2sini_2 = 15.2pm 1.0 Mjup, and orbits on a highly eccentric orbit of e2 = 0.691 pm 0.018. While we have not detected significant transit timing variations of HAT-P-13b, due to gravitational and light-travel time effects, future observations will constrain the orbital inclination of HAT-P-13c, along with its mutual inclination to HAT-P-13b. The HAT-P-13 (b,c) double-planet system may prove extremely valuable for theoretical studies of the formation and dynamics of planetary systems.

And so HATnet steals the title of "First discoverer of multiplanet transiting system."

Someone should have published sooner.....

Very awesome discovery.

Hmm. Reading the paper, I come across...

Quote :

Curiously, the recently announced Doppler-detection HD 126614 b (Howard et al. 2009) appears to have similar orbital characteristics to HAT-P-13c. Both are Jovian planets in a P > 1 yr, e=0.7 orbits around metal rich [Fe/H] ~= 0.5) stars.

Apparently hasn't popped up on ArXiv yet I guess.

Greg Laughlin posted on the oklo.org blog that improved measurements of HAT-P-13 b's eccentricity would enable the internal structure of the planet to be probed. I'm not yet sure how, but all I've figured out is that it requires the existence of an outer companion, i.e. HAT-P-13 c.

The paper that Greg linked to claims that if this is done, it would make the internal structure of b more well known than that of the solar system gas giants.

http://oklo.org/2009/07/28/a-look-inside-an-extrasolar-planet/

That's pretty neat actually. In a very handwavy way, the outer companion pumps the planet's eccentricity and tides damp it, and the rate of tidal damping depends on the planet's structure.