The first K2 observation of a transiting exoplanet

My life has been consumed recently with planning for the K2 mission (a mission where Kepler observes into the ecliptic). The Senior Review proposal to NASA has just been submitted and we have received over 100 proposals from community scientists to observe targets during our first science campaign.


K2 managed to catch one transit of WASP-28b during a short test observation in Jan 2014. The data were obtained at 1 min intervals.

We have some data on the ground and the good news is that we can detect planets! We have observed our first exoplanet transit, WASP-28b – A previously known hot Jupiter type planet. I’ve posted an image of the transit, it looks beautiful. The noise may seem a little high but this is because the data were taken at 1-min cadence rather than our more usual 30-min cadence. There is also only one transit so we don’t benefit from overlaying multiple transits.

I’ve also being doing some work on estimating what sizes of planet we are going to be sensitive to. It looks we are going to be able to find Earth-sized planets  orbiting relatively bright G and K type stars and well as around fainter M-dwarfs. This is great because these are the stars we are going to be able to get follow-up ground based observations of. I can’t wait to get some more data on the ground.

A second planet with a comet-like tail

Last year Saul Rappaport and team reported the discover of what appeared to be a slowly disintegrating planet. The evidence pointing to this was a planet transit-like event of a body very close to its star. The size of the body appeared to change dramatically over time and the shape of the transit was not symmetric. They worked out that if they simulated a planet that was slowly losing material and had a comet-like tail they could reproduce the observations. This was a very neat discovery and there has been plenty of follow-up observations and theoretical work performed to understand that system. However, it was not clear whether this was an extremely rare event or a long lived and relatively common occurrence among very hot, small plant

Well, now we have another one. KOI-2700b is the second planet with a tail found in Kepler data. We actually identified this one a couple of years ago but could not explain what was going on (this was before the first disintegrating planet). The transit was very asymmetric in shape so we dubbed it planet Nike (as in a Nike tick).

The planet goes around its parent star every 22 hour and the tail seems to take persist for about about 5 hours. This means that the tail extends behind the planet for about a quarter of the orbital circumference.

One final cool thing we found is that the depth (and indeed shape) of the transit it changing over times. We see the transit become about half as deep over the four years we observed this planet. Seems like we caught this thing shortly before it looses its tail and becomes too small to detect.


The brightness of the star KOI-2700 decreases when a planet with a large tail passes in front of it. The unusual transit shape caused us to dub this Planet Nike.



The Two-Wheel Kepler Mission will be awesome

I was in a seminar last week where exoplanet science was described as being in the post-Kepler era. This phrase has much merit given how dramatically our understanding of exoplanet populations has changed since Kepler launched. For example in 2007 the state of the art simulations predicted 10-100 Earth mass planets do not form. Kepler data has shown this predicted to be spectacularly wrong. Turns out most planets all into this range.

However, in the talk post-Kepler era was used to describe the era after Kepler stops taking data. Which is now because Kepler is dead, right? Erm, actually no. Kepler is alive and, if not well, doing pretty good. What is true is that Kepler cannot point accurately at its original field, but there are parts of the sky where it can really kick ass – in the ecliptic. Most of the current information is subject to change but our best guess is that we will be able to observe some 10’s of thousands of targets continuously for about 2.5 months. Now here is the real exciting part. Its very possible that we will be able to obtain better than 100 parts per million photometry. That means we could easily detect rocky Earth-sized bodies around Sun-like stars, albeit pretty hot rocks. This capability is unique, nothing else can achieve precision as good as that. This is why I’m super excited by two wheel Kepler. We just need a good name for this refactored mission.

Robust exoplanet masses from transit timing variations

I’m going to try to post on a semi-regular basis about whatever astronomy thing has interested me on a given day. it’s probably be a bit random and not well explained.

Today I was chatting with some by Kepler buddies about a paper by Ofir where they measure the mass of two planets orbiting KOI-1574 using transit timing variations. The part I find interesting is that Ofir finds one of the planets has a density of 0.1 g/cc – much lower than any planet in our own Solar System. We were concerned with the uniqueness of the solution given there are only 4 transits of the planets of each planet in the Kepler data.

Dan Foreman-Mackey has been developing an n-body/transit model code that can be used to used to model systems like KOI-1574. I hope/plan to run an MCMC simulation that should reveal whether the ultra-low density found by Ofir is significant and robust. Not that I’m trying to pick on Ofir, his analysis seems perfectly reasonable to me. It does however provide a convenient example to test the code upon.


We’re back!

We’re back, and by that I mean the US government is back. For the last 16 days I’ve been locked out of my office at NASA Ames. As a contractor I’ve been allowed to work, indeed I’ve had quite a productive few weeks.

The first week of the shutdown the SETI Institute in Mountain View kindly hosted me and provided free coffee! With all the Kepler science office in the same room we were able to chat about a few projects we were all working on and it looks like a few papers that have been a long time coming are nearly finished (Kepler planet catalog papers).

Last week I took the opportunity to visit New York University as a guest of David Hogg. We have a few projects together that have been left on the backburner. Hopefully we/I will get these going this time. One of the more straight forward ideas we have is to measure limb darkening using transit of multi-planet systems.

Anyway, I’m going to try and use this blog as a bit of a research/work journal. It may not work, let’s see.

Announcing Kepler-69c – a super-Earth-sized planet in or near the habitable zone of a Sun-like star

I’m about to do the press conference to announce this system but I wanted to make the paper available. The paper is available from here.

The press conference should be on NASA TV now.


A recording of the press conference can be found on the NASA UStream page. I’m not sure how long it will last there though.

I did a live interview with the BBC Radio 4 program The World Tonight. That interview can be found via this link – Radio 4 interview.

Does the IAU name exoplanets?

Recently the International Astronomical Union, IAU, put out a press release where they discussed the selling of planet names. I have some concerns about selling names and such but that is a separate point. What surprised me was that the IAU press release implied that there is an official naming scheme for exoplanets and that they manage it. I recently announced the discovery of three exoplanets and I don’t think I or anyone else on the team asked for permission from anyone to name them Kepler-37b, c and d. As far as I can tell, there is no official naming scheme for an exoplanet. Indeed, there isn’t even an official definition of what an exoplanet is.

What is it like to be a planet hunter?

Yesterday I spend the afternoon with a film crew from the CBS Sunday Morning News. I got interviewed by Barry Peterson who earlier this year was shot at in Syria. I’m not quite sure what a serious news journalist was doing talking to me but it was fun nevertheless.

They were asking about what it’s like to be a planet hunter. One of the questions they wanted me to answer was ‘What is it like to find a planet? Describe the emotions’. That’s actually a fairly difficult thing to do. There is not really a single moment when you discover something and it isn’t really an individual thing. Many, many people are involved in anything that comes out of a large project like Kepler. However, there were several points in my two recent papers (one a sub-Mercury-sized planet, the other I’m not meant to talk about yet but will come out on Thursday this week) where I got excited. The first was when flipping through the data you find something unusual or extraordinary. The second is when you find that no one else is on to this yet – its not already published and from what you can tell no one else is working on it. This is the spine-tingling moment.

However, after this initial excitement follows months of hard work and strife.  The time it takes to go from having an interesting candidate to having a finished paper can be many months. The week or two before a paper is submitted can be intense. Everyone wants the paper out right away. Long hours of writing and editing are generally required. After the paper is submitted the overwhelming emotion is relief. Relief that you can relax for a little while.

By the time the Kepler-37b paper came out I’d been working on the system for well over a year. I was no longer excited by the work because it was old news, not only to me but to everyone around me. I was more excited about moving onto other projects than talking to journalists.

Anyway, the interview with CBS will be shown on CBS Sunday Morning News with Charles Osgood on 21st April. I think the show will be on at 9.30am on the east coast but 6.30am pacific. Apparently, it should be posted online too.

Press coverage for a sub-Mercury-sized exoplanet

This already a week old now but I thought I’d post some of the press stories. I’ve spent the last year writing a paper that was published in Nature announcing the discovery of an exoplanet smaller than Mercury. This work has taken a long time so it is great that it has finally become public.

We managed to get a lot of press attention. Some of the articles are listed below. Additionally, one of the co-authors of the paper did a great interview on Australian TV.


The information below comes from the NASA public affairs team.

The AP (2/21, Chang) reports scientists using the Kepler telescope data have discovered a planet about the size of the moon, although the exoplanet, called Kepler-37b, “orbits too close to its sun-like star and is too sizzling to support life.” It was discovered by Thomas Barclay of the Ames Research Center and it “took more than a year and an international team to confirm that it was a bona fide planet.” UC Berkeley’s Geoff Marcy said, “This new discovery raises the specter that the universe is jampacked, like jelly beans in a jar, with planets even smaller than Earth.” Alan Boss of the Carnegie Institution for Science, called the discovery a “milestone” towards finding an Earth-like planet.

The Los Angeles Times (2/21, Brown, 692K) reports Barclay said scientists are “breaking new ground” with the discovery, who noted that a total of three planets have been found in the system. While none are similar to Earth, Barclay, according to the article, claimed the “discovery is still ‘really good news’ for the search for habitable worlds…because it demonstrates that the Kepler telescope is sensitive enough to find Earth-sized planets with longer orbits ‘in the not-too distant future.'” Caltech’s John Johnson, who was not part of the study, praised Kepler for making exoplanet discoveries “blasé” with the what it has found.

The Boulder (CO) Daily Camera (2/21, Brennan, 40K) reports on the ties the mission and the discovery has to the region as Barclay said, “This project would not have been possible if not for the exquisite instrument built at Ball.” Meanwhile, Alan Gould, a co-investigator for education and public outreach for the Kepler mission, said, “The significance as far as I’m concerned is that when the mission first started it was hoped that we could find planets smaller than Mars, and we thought it might be able to find planets as small as Mercury. … So, this is momentous in that here is a planet smaller than Mercury, and it is totally due to the incredibly precise light measuring capability of the Kepler instrument.”

According to the Christian Science Monitor (2/21, Spotts, 47K), in another result from this study, “Kepler’s ability to take very precise measurements of the star’s own light helped the team develop a highly accurate estimate of the star’s size and mass.”

SPACE (2/21, Howell) notes “Barclay and his team took great care to confirm the existence of planets around Kepler-37.”

Also covering the story are Bloomberg News (2/21, Lopatto), CBS News (2/21, Harwood) “Space” website, BBC News (2/21, Palmer), Popular Science (2/21, Nosowitz, 1.3M), Wired (2/21, Mann, 798K) “Wired Science” blog, ScienceNOW (2/21, Croswell, 128K), New Scientist (2/21, Aron), Discovery News (2/21, Klotz), another Discovery News (2/21, O’Neill) article, Gizmag (2/21, Szondy), UK’s Daily Mirror (2/21, Rankin, 1.32M),PolicyMic (2/21, Marin), Scientific American (2/21, Matson, 483K), China’s Xinhua (2/21) news agency, Sen(2/21, Black), Universe Today (2/21, Atkinson), The Escapist (2/21, Bolding), Geekosystem (2/21, Chant), andGizmodo (2/21, Diaz).