TRAPPIST-1 : Transiting Earth-Sized Planets Around a Nearby Ultracool Dwarf

Abstract:

We request a modest amount of time to confirm the binary nature of the transit of TRAPPIST-1d.

http://ssc.spitzer.caltech.edu/warmmission/scheduling/approvedprograms/ddt/12126.txt

What is TRAPPIST-1d ??

I'm guessing it's the third planet in the first system discovered by this project.

They don't give any indication on the nature of the object; binary stellar transits are not unheard of.

I would doubt that TRAPPIST would be in a position to detect a multiple-transiting planetary system, as that would likely require longer orbital periods than those observable for even wide-field telescopes, and I think TRAPPIST is single-target. It's probably some odd naming convention.

Edit: One can interpret "binary nature of the transit" as "transit due to a binary system", which is obviously much more likely a priori, though the grammar is strange. I would still advice against freaking out.

There is blogging activity concerning TRAPPIST-1d, however it all appears to be in Russian. Some pages with Google Translate:

Открыта первая экзолуна?

Opening of the first exomoon?

January 19 online Spitzer Space Telescope appeared mysterious application unscheduled surveillance. Description of the application consists of just one sentence: a group of astronomers led by Michael Gillon asks for 5.7 hours Space Telescope observations to confirm the dual nature of the transit facility TRAPPIST-1d.

Despite the reticence we can assume that it is a unique discovery. Designation TRAPPIST-1d shows that 60 cm infrared telescope at the European Southern TRAPPIST Observatory opened its first planetary system. The only search for planets, which was held in this small telescope became a pilot review of the 50 nearest brown and later red dwarfs in preparation for a large-scale project SPECULOOS (under the same management Michael Gillon). The letter d in the notation just says that planetary system is open, at least three stopovers planet. The phrase alludes to the dual nature of the object, it is a double planet or a planet with a very large moon.

This discovery sounds rather fantastic: the telescope Kepler discovered several single-planet systems in late red dwarfs, but has not yet published any detection of double transit. In the near future on the website Spitzer will be available coordinate system TRAPPIST-1. In the meantime, we can conclude that the system is 5-10 parsecs from Earth, since the telescope was looking TRAPPIST transit of the planet in 50 brightest later red and brown dwarfs. The sensitivity of this survey reached the transit of the planet's detection capabilities with a radius of 0.6 - 1.1 Earth radii at the level of 5 sigma confidence.

Больше новых подробностей о системе TRAPPIST-1

More details about the new system TRAPPIST-1

Yesterday's unusual request for Spitzer forced me to dig a little bit about the mysterious system TRAPPIST-1. Since the 60-cm telescope TRAPPIST is in the European Southern Observatory (ESO), it is logical to assume that the system with the same name already active there there. Indeed, search the database by keyword ESO TRAPPIST-1 shows that the system was observed in November and December last year. These observations were carried out by two non-routine programs: "CONFIRMING THE ECLIPSING-BINARY NATURE OF A NEARBY ULTRA-COOL DWARF" and "THE PECULIAR PHOTOMETRIC VARIABILITY OF A NEARBY ULTRA-COOL DWARF" total duration of 3 hours. Both programs have been carried out under the supervision of the same M. Gillon, and consisted of observations on the camera HAWKI, mounted on 8-meter telescope of the VLT.

Moreover, for a given object TRAPPIST-1 in these observations lead and coordinate 23 June 28 -05 01 50. Search these coordinates in Simbad shows that of the adjacent areas (43 arcseconds) is a brown dwarf 2MASS J23062928- 0502285.

It was first observed in 2000 after comparing reviews POSS II images and 2MASS, taken with an interval of 10 years (proper motion of more than 1 arcsecond per year). Photometric distance to it was estimated at 11.3 parsecs, and the spectral class M7.5. In 2006, unable to determine the exact distance and before him: 12.2 parsecs (trigonometric parallax is equal to 82.58 ± 2.58 mas).

There is no doubt that this is one of the brightest in the sky brown dwarfs. So 2M J2306-0502 was among the 15 sites that have been sought within the planet's test review ROPS (Red-Optical Planet Survey) spectrograph UVES (Telescope VLT).

Four radial velocity measurements made for this brown dwarf, have not shown the presence of large variations of the radial velocity:

Similarly ended unsuccessfully searching for partners and high resolution photos. Including with the Hubble Space Telescope and the largest ground-based telescopes.

The database ESO is no information about the sharp increase in the number of high-resolution spectra obtained (for example, the spectrograph HARPS), which is to talk about trying to measure the masses of transiting planets discovered. This is not surprising, in visible light 2M J2306-0502 has a brightness of only 19 magnitudes. The near infrared situation is much better: R = 16.5, I = 14.0, J = 11.3, H = 10.7, and K = 10.3. On the other hand, the fact that this object has a large proper motion, greatly simplifies the procedure of exclusion scenario background eclipsing binary. In addition, the detection of multiple transiting planets to limit the mass of the planet through the timing of their transits (tracking changes in the timing of the eclipse).

Thank you Mongo !!
Very very exciting !

Hmmm, so that sounds like it might be a brown dwarf triple system or something along those lines.

https://archive.stsci.edu/proposal_search.php?id=14493&mission=hst
"The system proximity (12 pc), its large planet-to-star radii ratios and high systemic velocity (-56 km/s) make it an amazing target to study the state and evolution of terrestrial planets atmospheres around a late M dwarf in the UV."

It TRAPPIST-1 or 2MASSW J2306292-050227 as:
http://simbad.u-strasbg.fr/simbad/sim-id?Ident=2MASSW%20J2306292-050227
"Parallaxes (mas): 82.58 [2.58]"
"Radial velocity / Redshift / cz : V(km/s) -56.3"

Spitzer Telescope has observed six transits the third planet.
http://za-neptunie.livejournal.com/214653.html

Possible period the third planet of 0.8 or 1.6 days.

Very interesting news, thanks for finding this!

Quote :

We just discovered 3 short-period Earth-sized planets transiting a nearby ultracool dwarf star.

Well, that's direct.

This seems like a much more interesting discovery than was initially indicated. Very little is known of the planet distribution for stars/brown dwarfs beyond early-mid-M dwarfs for all methods except microlensing, so this is very much welcomed.

I'm not sure why the scientists would specifically choose to refer to the target as "binary", then switch to "planet", though.

Hopefully we'll see more conclusive information soon. Are there any conferences scheduled for the near future?…

zorro83 wrote:

Abstract:

We request a modest amount of time to confirm the binary nature of the transit of TRAPPIST-1d.

http://ssc.spitzer.caltech.edu/warmmission/scheduling/approvedprograms/ddt/12126.txt

Looks like it's been updated, new title is "On the eclipsing binary nature of a nearby ultracool dwarf". Abstract:

Quote :

The eclipsing binary nature of a nearby ultracool dwarf has just been revealed. The aim of this DDT is to investigate this nearby system further through high-precision infrared time-series photometry.

ESO press release :


http://www.eso.org/public/unitedkingdom/news/eso1615/?lang

Three Potentially Habitable Worlds Found Around Nearby Ultracool Dwarf Star

Astronomers using the TRAPPIST telescope at ESO’s La Silla Observatory have discovered three planets orbiting an ultracool dwarf star just 40 light-years from Earth. These worlds have sizes and temperatures similar to those of Venus and Earth and are the best targets found so far for the search for life outside the Solar System. They are the first planets ever discovered around such a tiny and dim star. The new results will be published in the journal Nature on 2 May 2016

The paper :

http://www.eso.org/public/archives/releases/sciencepapers/eso1615/eso1615a.pdf

Temperate Earth-sized planets transiting a nearby ultracool dwarf star

Interesting system, will be interesting to see what the atmospheres (if any) are like on planets so close to this kind of star (apparently just on the stellar side of the star/brown dwarf divide).

I had thought that one of the microlensing systems had a similar host star, but I guess the parameters are far less constrained than this one.

Water loss from Earth-sized planets in the habitable zones of ultracool dwarfs: Implications for the planets of TRAPPIST-1
http://arxiv.org/abs/1605.00616

(I've changed the thread name to make it more generally applicable to the system)

Here is Nature paper:

Temperate Earth-sized planets transiting a nearby ultracool dwarf star

Quote :

Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as ‘ultracool dwarfs’1. This heterogeneous group includes stars of extremely low mass as well as brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15 per cent of the population of astronomical objects near the Sun2. Core-accretion theory predicts that, given the small masses of these ultracool dwarfs, and the small sizes of their protoplanetary disks3, 4, there should be a large but hitherto undetected population of terrestrial planets orbiting them5—ranging from metal-rich Mercury-sized planets6 to more hospitable volatile-rich Earth-sized planets7. Here we report observations of three short-period Earth-sized planets transiting an ultracool dwarf star only 12 parsecs away. The inner two planets receive four times and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star8. Our data suggest that 11 orbits remain possible for the third planet, the most likely resulting in irradiation significantly less than that received by Earth. The infrared brightness of the host star, combined with its Jupiter-like size, offers the possibility of thoroughly characterizing the components of this nearby planetary system.

TRAPPIST-1 on Drew Ex Machina: Habitable Planet Reality Check: TRAPPIST-1

It looks like K2 Campaign 12 will be observing this system, hope the spacecraft lasts that long and has good enough performance to be able to get useful data on such a dim star.

Quote :

hope the spacecraft lasts that long and has good enough performance to be able to get useful data on such a dim star.

It cannot be denied that Kepler's health is tenuous, but it can at least be said that observing the star should not be a problem; though TRAPPIST-1 has a V magnitude of 18.80, the Kepler bandpass extends into the infra-red somewhat. According to the EPIC, it should have a Kepler magnitude of 12.92, which is quite high for a K2 star! One should expect a per-point precision of something like 150 ppm (assuming current instrument stability), compared to transit depths of >6500 ppm. Though reaching <<1 min precision on the transit times will be difficult, is is most definitely possible.

This system is a very important discovery, as it signals that planet detection around UCDs is possible from the ground. Despite short transit durations, no prior knowledge, and a large number of targets to observe ("~60"), the TRAPPIST team managed to pick out three transit signals, including what is likely the longest-period transit signal detected from the ground a priori, in only a few months. This is a large uptick in efficiency compared to conventional ground-based transit surveys.

Though particularly meaningful statistics are not possible with a single system, some back-of-the-envelope calculations indicate that, in the conservative case that this is the only detection out of 60 targets (which is an egregious simplification at best), then the frequency of systems like this is within something like an order of magnitude of 0.4 per star. This is effectively a meaningless statement at the current juncture, but it speaks of the remarkable nature of the authors finding planets so soon. A handful more systems will be enough to say something meaningful about the planet rate around very-low-mass stars.

…They haven't mentioned anything about the Spitzer observations, have they? I wonder what that's about.

Strong XUV irradiation of the Earth-sized exoplanets orbiting the ultracool dwarf TRAPPIST-1
http://arxiv.org/abs/1605.01564

The original discovery paper is now on arXiv, as well as a paper suggesting JWST could detect ozone in these planets with a reasonable amount of effort.

Temperate Earth-sized planets transiting a nearby ultracool dwarf star
http://arxiv.org/abs/1605.07211

Habitable worlds with JWST: transit spectroscopy of the TRAPPIST-1 system?
http://arxiv.org/abs/1605.07352

http://arxiv.org/abs/1606.01103

A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c

Here, we report a space-based measurement of the combined transmission spectrum of the two inner planets made possible by a favorable alignment resulting in their simultaneous transits on 04 May 2016. The lack of features in the combined spectrum rules out cloud-free hydrogen-dominated atmospheres for each planet at 10-σ levels; TRAPPIST-1 b and c are hence unlikely to harbor an extended gas envelope as they lie in a region of parameter space where high-altitude cloud/haze formation is not expected to be significant for hydrogen-dominated atmospheres. Many denser atmospheres remain consistent with the featureless transmission spectrum---from a cloud-free water vapour atmosphere to a Venus-like atmosphere

Regarding the question of the detectability of TRAPPIST-1 and similar systems with K2.

Demory et al. "Probing TRAPPIST-1-like systems with K2"
http://arxiv.org/abs/1606.08622

Suggests a recovery rate of 10% because of the redness of the host star.

NASA press-release :

http://www.nasa.gov/press-release/nasa-s-hubble-telescope-makes-first-atmospheric-study-of-earth-sized-exoplanets

NASA’s Hubble Telescope Makes First Atmospheric Study of Earth-Sized Exoplanets

TRAPPIST-1 appears to be a single star, which makes the planetary properties more secure.

Gemini Observatory press release

Paper: Howell et al. (2016) "Speckle Imaging Excludes Low-Mass Companions Orbiting the Exoplanet Host Star TRAPPIST-1" (paywalled)

Now on arXiv.

Speckle Imaging Excludes Low-Mass Companions Orbiting the Exoplanet Host Star TRAPPIST-1
https://arxiv.org/abs/1610.05269

https://www.nasa.gov/press-release/nasa-to-host-news-conference-on-discovery-beyond-our-solar-system

NASA to Host News Conference on Discovery Beyond Our Solar System

NASA will hold a news conference at 1 p.m. EST Wednesday, Feb. 22, to present new findings on planets that orbit stars other than our sun, known as exoplanets. The event will air live on NASA Television and the agency's website.

Details of these findings are embargoed by the journal Nature until 1 p.m.
.
The briefing participants are:

Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington
Michael Gillon, astronomer at the University of Liege in Belgium
Sean Carey, manager of NASA's Spitzer Science Center at Caltech/IPAC, Pasadena, California
Nikole Lewis, astronomer at the Space Telescope Science Institute in Baltimore
Sara Seager, professor of planetary science and physics at Massachusetts Institute of Technology, Cambridge


 N.B : Michael Gillon is a member of the TRAPPIST team...