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February 26th, 2009 5 comments

The primary transit of HD 80606b

After 10 days of no news, definitively flat news (Arizona) and tantalizing hints in my inbox, the HD 80606b transit story is resolving itself dramatically.

Earlier today, Stephen Fossey, Ingo Waldmann and David Kipping submitted their paper on the detection. I based the diagram on the results of their photometry, which points to a twelve hour transit, and a planetary radius just larger than Jupiter:

Fossey et al. photometry of the primary transit of HD 80606b

The Fossey et al observations were made using two small telescopes at the University College London’s observatory in Mill Hill, North London. (Co-author Ingo Waldmann is a final-year undergraduate project student.) It’s certainly been a long time since an observational astronomical discovery of this magnitude has made from within the London City Limits!

Also in my inbox this morning was an e-mail from Jose Manuel Almenara Villa, who made the definitive initial observation of HD 17156 (and made the initial announcement on the comment section of this weblog). He writes, I know it’s late, but here there are the data from Tenerife. The egress is fully there, fully present. Nice work!

Jose Manuel Almenara Villa Photometry for HD 80606

And then, no more than an hour ago, another dramatic update. In an e-mail to myself and Jean Schneider, Enrique Garcia-Melendo writes:

Dear Greg and Jean,

We observed the transit of HD80606b.

Please find attached the submitted paper to the ApJ. The manuscript will also appear at http://arXiv.org/abs/0902.4493

Best regards,
Enrique Garcia-Melendo

Title: Unconfirmed Detection of a Transit of HD 80606b
Authors: E. Garcia-Melendo and P. R. McCullough
Categories: astro-ph.EP
Comments: Submitted to ApJ, 11 pages, 4 figures.

We report a times series of B-band photometric observations initiated on the eve of Valentine’s day, February 14, 2009, at the anticipated time of a transit of the extrasolar planet HD 80606b. A transit model favored by the data has minimum light of 0.990 times the nominal brightness of HD 80606. The heliocentric Julian date (HJD) of the model’s minimum light is 2454876.33, which combined with the orbital period P = 111.4277 pm 0.0032 days, longitude of periastron, omega = 300.4977 pm 0.0045 degrees, and time of mid-secondary eclipse HJD 2454424.736 pm 0.003 (Laughlin et al. 2009), refines the eccentricity, e = 0.9337 +0.0012 -0.0004}, and the inclination, i = 89.26 +0.24 -0.04 degrees. The duration of the model transit is 0.47 days, and its four contacts occur at HJD 2454876 plus 0.10, 0.24, 0.42, and 0.57 days. We observed only the last two contacts, not the first two. We obtained “control” time series of HD 80606 on subsequent nights; as expected, the “controls” do not exhibit transit-like features. We caution that 1) the transit has not been confirmed independently [note: no longer true.]; 2) we did not observe the transit’s ingress; 3) consequently, we cannot reliably measure the relative sizes of the planet and its star in a model-independent manner, and 4) hence, the other values derived herein are also model dependent.

Now here’s the kicker — the Garcia-Melendo & McCullough paper was submitted on Feb. 23rd…

Update: I just heard from Shigeru Ida at Tokyo Institute of Technology, who has coordinated a number of photometric campaigns by amateur observers in Japan. It turns out that it was either rainy or totally cloudy on the night of the transit ingress (Feb. 13/14) for all of the observers. Bummer. The following night, the conditions were a little better, allowing several observers to get noisy baseline data.

Categories: worlds Tags: , ,

go

February 12th, 2009 3 comments

Image Source: Mearth Live.

Update 4 : Feb. 14 2009, 07:12:00 UT

The first reports are coming in. Gregor Srdoc in Croatia got a lightcurve through most of the night for HD 80606 combined with HD 80607. No sign of a transit, but the data is relatively noisy due to imperfect weather.

Veli-Pekka Hentunen reports that weather conditions in Finland were bad generally, and were specifically bad in Varkaus.

At least four sets of observations from various locations in Arizona are currently underway, including both the 40” and the 1.3m at USNO Flagstaff under the able command of Paul Shankland.

Jonathan Irwin reports that data from Mearth through 5 UT shows no sign of an egress.

Ohio State Grad Student Jason Eastman reports on his remote Demonex observations (from the comments page):

Halfway through the night…

We started observing at UT 02:30 in the V band. No sign of an egress at the ~0.005 mag level.

http://www.astronomy.ohio-state.edu/~jdeast/demonex/HD80606b.R.2009-02-14.jpg

That link will be updated with the entire night’s data in the morning.

So it’s not looking particularly good for a transit, but I’m really happy that data is coming in. We’ll have a definitive answer sometime tomorrow.

Thanks to everyone who observed. It’s really cool how a planet 190 light years away can bring observers all over the globe into a common mission.

Update 3 : Feb. 13 2009, 23:29:00 UT

We’re now closing in on the moment of inferior conjunction, which hopefully will wind up being the midpoint of a central transit. The current weather in Europe looks like it’s clear for observers in Finland and Northern Italy, so it’s now quite likely that we’ll get a definitive answer from the campaign.

No word yet on whether an ingress was observed, but Jonathan Irwin did send a nice light curve from last night’s baseline run with Mearth. He writes:

Here’s our entire night of data (about 11 hours) from one telescope, using 80607 as the comparison star. Raw and binned x12 (about 5 minutes per bin). We are getting rms scatter of about 1.6 times Poisson with this fairly quick reduction.

There is usually a slight offset when the target crosses the meridian (data point 777) due to flat-fielding error, that I have not removed in this – over the ~20 arcsec separation of the pair it’s pretty small. There is also a bit of a blip there as my guide loop recovers its lock after crossing – still needs a little tuning :)

Fingers crossed for tonight!

Update: Clear Skies in Arizona. Dave Charbonneau writes:

http://mearth.sao.arizona.edu/live/

Clear skies. You can even watch the images in real time, and see how many
MEarth scopes are on ‘606…

Update 2 : Feb. 13 2009, 17:04:00 UT

It’s now the middle of the night in the Far East, and the transit window has opened. The weather in Japan looks a little spotty, but Southern China is in the clear.

Observers in Arizona reported good weather last night, but the forecast is a little iffy for tonight.

In addition, I just got an e-mail (UT 17:48) from Gregor Srdoc in Croatia, who is on the sky under quite good conditions just after nightfall…

Update 1 : Feb. 13 2009, 06:03:03 UT

There’s about a half-day left until the possible start of the ingress. On the map above, I’ve marked the locations of confirmed observers with small red dots. HD 80606b is 190 light years above the spot labeled with the orange circle.

Observers in the US are currently taking data of both HD 80606 and its binary companion, HD 80607. It’s always good to have an out-of-transit baseline photometric time series.

Dave Charbonneau checked in with a status report:

MEarth is ready. You can watch us in real time at
http://mearth.sao.arizona.edu/live/

If the roof is closed, it is cloudy.

The up-to-the-minute stop-action animations showing the disconcertingly reptilian movements of the telescopes are completely mesmerizing. Mearth (pronounced “mirth”) is located at the Fred Lawrence Whipple Observatory on Mt. Hopkins in Arizona, and spends most of its nights searching for potentially habitable terrestrial planets transiting nearby M dwarfs. The telescopes have a list of ~2000 nearby red dwarf stars. Each star is subjected to repeated visits of ~30-45 minute duration. The idea is to catch transiting planets in progress and to broadcast the information to larger telescopes that can obtain immediate real-time photometric confirmation of a discovery. (For a more detailed overview of Mearth, see Irwin, Charbonneau, Nutzmann & Falco 2008.)

Update 0 : Feb. 12 2009, 22:47:40 UT

I’ll be posting updates on the global HD 80606b transit campaign as I get them, with newer updates going to the top of this post.

A number of observers have indicated that they’ll be on the sky. Right now, it looks like telescopes are confirmed for Finland, Israel, Italy, Japan and the US. Given the vagaries of the weather, however, it would be great if we can get as much coverage as possible. As Vince Lombardi would have put it, “We’re looking at 15%, so if you can get 1%, get out there and give 110%!”

Everyone is encouraged to comment as the campaign progresses (click the number next to the post title to access the discussion page). I’ve lifted the restriction that only allows registered oklo users to comment, but all comments are now held for moderation, in order to keep the Viagra contingent off the air.

ready set…

February 12th, 2009 Comments off

Even as I write, HD 80606b is closing in fast on its inferior conjunction. It’s basically a roll of a die, a roughly one in 6 chance, that the orbital alignment is good enough for a primary transit to be observable. (The odds are boosted from the a-priori geometric probability of 11% to ~15% by the fact that the secondary transit was fully consistent with an uninclined passage directly behind the star.)

Here’s the situation:

A central transit will last roughly 16 hours, with the ingress best suited for observers in the Far East, and the egress best suited for observers in North America. Europe is the place to be for transits that are closer to grazing. HD 80606 itself is favorably sited in Ursa Majoris, and is at low air mass for basically the entire night, especially at higher latitudes.

Good luck to everyone who’ll be observing!

WASP-12b

January 19th, 2009 6 comments

WASP-12b. Now there’s an unpleasant travel destination.

Nevertheless, this particular planet, whose transits were recently announced by the SuperWASP collaboration, is quite a remarkable world. For starters, inveterate bottle-poppers can celebrate a WASP-12b New Year on literally nine out of every ten days — the orbital period is a mere 26 hours and 11 minutes. The temperature of the planetary photosphere at the substellar point likely exceeds 2500K. Cherry orange, to be exact.

Because of its ultra-short orbital period, WASP-12b is attracting quite a bit of interest. The planet has a radius 1.8x larger than Jupiter, which should make it eminently feasible to detect secondary transits from the ground in either the optical or near-infrared. One expects, furthermore, that a planet with an orbital period just a shade over a day should have long since damped out its eccentricity, but (to better than 2-sigma) the orbit appears to be non-circular, with e=0.049 +/- 0.015. Even if another planet exists in the system, there should long since have been evolution to a tidal fixed point, followed by circularization. If the orbit really is eccentric, then GR precession of the periastron amounts to a whopping 0.2 degrees per year, nearly 2000x faster than Mercury’s stately 43” per century.

I got an opportunity to visit Harvard this month, and while I was there, David Latham remarked that he had used a remotely operated telescope in Arizona to get a high-precision light curve of a WASP-12b transit. Latham is a meticulous observer, and so, in order to get the best possible baseline, he had cued up the telescope a number of hours prior to the predicted ingress. He related that he’d been completely startled to find, upon analyzing his photometry, that the transit had occurred several hours ahead of schedule. Without a doubt, transit timing variations are going to be one of the big exoplanet stories of 2009, but they’re going to be measured in seconds, not hours. Imagine the commotion that would result if the Sun rises a few hours late tomorrow morning!

The WASP-12 mystery was solved by the amateur astronomers Veli-Pekka Hentunen and Markku Nissinen of Taurus Hill Observatory near Varkaus, Finland. Bruce Gary, who runs the Amateur Exoplanet Archive forwarded the news of their work:

AXA contributors and TransitingPlanets members,

I just received two data files for WASP-12 as observed by Veli-Pekka Hentunen and Markku Nissinen (Finland) which suggest that the discovery paper for this exoplanet has a misprint for the ephemeris. Their observations on January 1 was a “no show” (attached) whereas their observations on January 4 had a nice transit (attached). According to the discovery paper’s ephemeris there should have been a transit on January 1 but not on January 4. However, the discovery paper has a discrepancy between the stated ephemeris and the stated HJD for WASP survey observations. The Hentunen and Nissinen observations can be explained if the discovery paper’s stated WASP survey HJD is correct and their HJDo has a number transposition, such that HJDo = 4506.7961 (instead of 4506.9761). This is described on the AXA web page for WASP-12: http://brucegary.net/AXA/WASP12/wasp12.htm

[…]

We amateurs have to keep the pro’s honest! Nice work, Veli-Pekka Hentunen and Markku Nissinen.

Bruce L. Gary, webmaster
Amateur Exoplanet Archive

Indeed! The typographical error in the discovery ephemeris has now been corrected, and with it, the puzzling “early” transit was revealed to be a completely separate event in the unending sequence of near-daily occultations. It seems somehow fitting that a seemingly alarming discrepancy for the hottest planet known was resolved by a pair of dedicated amateur observers during the long, dark, and frozen Finnish nights.

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