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8 november 2011: Asteroid 2005 YU55 came very close to Earth!
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2005 YU55 came in the night of November 8 to 319 000 km of the Earth's surface,
less than the distance from Earth to the Moon. Its speed is estimated to 46 600 km / h. This asteroid is on
an orbit that passes at regular intervals in the vicinity of Earth, Venus and Mars. But Tuesday, it did the
closer approach to our planet for at least 200 years. The next time an asteroid as big should come within a
distance comparable to the Earth will be in 2028. Radar images show a spherical body 400m diameter.
One of our objectives with TRAPPIST beeing the study of small solar system bodies,
we joined an international observing campaign to characterize this body. We were able to follow the asteroid
for several hours during this close encounter at high speed and take hundreds of images. The image shows
the asteroid in the center of the field. The exposure time is 10s, and the telescope is traching the asteroid,
so the stars are trailed.
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Near Earth asteroid 2005 YU55
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27 october 2011: Eris, unveiled by TRAPPIST telescope
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This is a unique event that we had the opportunity to observe November 6,
2010 with our robotic telescope, TRAPPIST, installed at the La Silla Observatory in Chile. The dwarf
planet Eris, the body most distant in the solar system, located 14 billion km from the Sun or three times
farther than Pluto, fell right in front of a star whose brightness went off for about thirty seconds
(news 06 Nov 2010). Unlikely event, this stellar occultation, also observed from another site in northern
Chile was used to measure the size of the distant planet with unprecedented accuracy (1163 +-6km radius).
This result is published today in the journal Nature (Sicardy et al. 2011). Eris is spherical and finally
the same size as Pluto (1150-1200 km) and not bigger as astronomers beleived since its discovery (which
led to the demotion of Pluto as a planet in 2006). Eris density has been revised upwards: it is a small
rocky planet (85%) and not a Panet made of ice like Pluto. This has implications to understand the
formation of the solar system. Finally, the surface of Eris has an albedo of 96% which is one of the most
reflective in the the solar system! While similar to Pluton about the surface composition, Eris has
no atmosphere. It has most probably making it looking like a mirror.
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credit/ESO
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Paper in Nature :
http://www.nature.com/nature/journal/v478/n7370/full/nature10550.html#f2
ESO Press Release :
http://www.eso.org/public/belgium-fr/news/eso1142/
Paper published sur le site Réflexions from the Liège University :
http://reflexions.ulg.ac.be/cms/c_39797/eris-la-lointaine-jumelle-de-pluton
Sky & Telescope :
http://www.skyandtelescope.com/news/Eris-and-Pluto-Does-Size-Matter-132755658.html
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23 august 2011: Replacement of the dome track (18-31 August 2011)
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View photo Gallery
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7 June 2011: The double occultation of Pluto and Charon of June 4, 2011
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This June 4, 2011, the TRAPPIST team did a unique and very difficult observation !
We managed to observe the dwarf planet Pluto and its moon Charon passing in front of a very faint star. The observations were performed
remotely from Belgium by E. Jehin using TRAPPIST, a 0.6m robotic telescope installed in 2010 at the
La Silla Observatory in Chile. Charon was the first to hide the star for about 50 seconds at 5:30 UT,
and about 12 minutes later, Pluto masked the same star during 2 minutes. The light curve of high
quality (see figure below) shows the two events and reveals the striking difference between a body
with an atmosphere (Pluto) and without atmosphere (Charon). Pluto's atmosphere is actually detected up to
an altitude of several hundreds of km from the surface of Pluto. It is the first time a double occultation
is observed from a single location. The phenomenon has been observed in two other sites in South America
(at the SPACE observatory
located in San Pedro de Atacama in Chile and at the observatory "Pico del Dias"
in Brazil). These observations are part of an international campaign led by a team from Paris Observatory
(Sicardy et al.). The comparison of these various data sets will provide valuable information on the parameters
of the orbit of Charon, the size of each object and the atmosphere of Pluto.
TRAPPIST had already succeded on Nov. 6, 2011, to observe the first occultation ever recorded of the dwarf
planet Eris (E.Jehin et al. IAUC 9184; Sicardy et al 2011, submitted to Nature).

Light curve of the occulted star (red) showing two drops of flux. The first, with a square box shape, is
due to the satellite Charon, whose size is estimated to about 1200 km. The second, twice as long, is due
to Pluto that has a diameter of approximately 2350 km. The curved shape of this occultation reveals
the presence of Pluto's atmosphere which refracts the light from the occulted star.
The blue curves are the reference stars and are used to control the
transparency of the sky which was excellent.
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15 April 2011: Two new asteroids discovered by students at the
University of Liège
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As part of an astronomy course on small solar system bodies (comets and asteroids),
given by E.Jehin for the Master is astrophysics of ULg,
students from the University of Liège discovered two new asteroids. It was in the lab using the robotic
telescope TRAPPIST, located in Chile, that this discovery was made. After having followed several
nights and hainge calculated their orbits, these asteroids were confirmed by the International Astronomical Union.. They
were given provisional names K11FE9A (or 2011 FA149) and K11FE9B (or 2011 FB149). Both asteroids are in the
main asteroid belt between Mars and Jupiter. The first measures a mere 1 km in diameter and the second could
be as large as 4 or 5 km. They rotate respectively in 4.2 years and 5.6 years around the Sun at average
distances of our star of 390 and 470 million km. Before a final name will be given they must be observed again
in the coming years when they will come again in opposition with the Sun.
Congratulations to Valentin Christiaens, Marc Levesque, Cyrielle Opitom, Laetitia Delrez, Lorraine Braibant
and Emilie Gloesener.
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The images of the discovery of the asteroid K11FE9A on March 31. We can see his movement among the stars during this sequence of images of 20 minutes.
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16 March 2011: First participation of TRAPPIST to the detection of an exoplanet
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TRAPPIST has contributed to the detection of the exoplanet WASP-23b.
This planet is a gas giant very similar in size and mass to Jupiter. It orbits at less than 0.04 astronomical units
of its host star, a dwarf star cooler and smaller than the Sun located about 600 light-years in the austral Puppis
constellation. The TRAPPIST data have confirmed the existence of the planet, first detected by the WASP survey, and
were used to measure precisely its size.
For more details, see http://arxiv.org/abs/1103.2603
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Transit
of the WASP-23b exoplanet (Triaud et al. 2011)
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14 February 2011: TRAPPIST observatory code is I40
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Today the Minor Planet Center attributed the observatory
code I40 to TRAPPIST !
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2 February 2011: TRAPPIST recovers comet 9P/Tempel 1
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This tiny fuzzy spike of light, lost in a rich field of the Milky Way
and 10000 times fainter than the faintest stars visible to the naked
eye, is periodic comet 9P/Tempel 1.
This comet was the target of the NASA Deep Impact mission in 2005 which
dropped a 500 kg copper bullet on its nucleus in order to study the
material released by the blast.
About 6 years later, on February 14, the 9P ~5km nucleus will be
revisited by the Stardust Spacecraft that collected several years ago
dust grains in the tail of comet 81P/Wild 2.
A similar story happened a couple of months ago with the Deep Impact
spacecraft itself that has also been rerouted to fly above the comet
103P/Hartley2 nucleus on November 4, providing spectacular images.
One of the goal of the new mission of the Stardust spacecraft will be to
take pictures of the crater, not seen yet, formed by the 2005 Deep
Impact. Currently at 2.6 AU from the Earth and lost in the glare of the
rising Sun, these images of the comet have been taken by the new belgian
telescope based in la Silla Observatory (Chile).
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Comet 9P/Tempel 1 moving among the stars
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21 December 2010: The asteroid that wanted to be a comet
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On December 11, asteroid (596) Scheila was discovered to have a small coma like a comet. There is a claim since a few years that comets are hiding in the main asteroid belt . Those so-called Main Belt Comets (MBC) would in fact be a newly discovered population of comets that formed in the outer edge of the Main Asteroid Belt. A few of them have been discovered and there could be thousands of them but still to discover. They are difficult to find because they are very weakly active. There is also the recent observation that big asteroid Themis has ices on its surface. These observations are very interesting because they show that comets and asteroids might not be exactly like we think and there might be more links between them than we thought before.
Is asteroid Scheila a MBC ? A very important observation to decide would be to discover if there is gas in its coma. Indeed comet activity is triggered by the sublimation of water and other ices like CO an CO2 by the Sun light. So far none of the MBC have been observed to have gas and some people claim that those objects are in fact activated asteroids for instance after a collision with a smaller asteroid.
We have been observing Scheila for a week with TRAPPIST using our narrow band filters and no gaseous species has been detected ! This is confirmed from deep spectra taken by our team at the ESO Very Large Telescope and still to be published. Scheila, like the object P/2010 A2 observed earlier this year, does not seem to be a comet. The coma is most probably rather resulting from an asteroid-on-asteroid impact. The coma is indeed vanishing in space from day to day and there is no sustain activity. Stay tune for more information !
(596) Scheila
http://adsabs.harvard.edu/abs/2011CBET.2632....2J
Jehin, E.; Manfroid, J.; Hutsemekers, D.; Gillon, M.; Magain, P.
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Asteroid Scheila surrounded by a dust cloud
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6 November 2010: TRAPPIST and dwarf planet Eris
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A first was achieved on the night of November 6 with TRAPPIST ! Emmanuël Jehin became the first astronomer to observe a stellar occultation by the dwarf planet Eris. This planet occulted a 15 magnitude star for a period of 30 seconds. This unlikely observation, combined with that also carried out in San Pedro de Atacama by Alain Maury and his team, will enable the size of Eris to be measured to within a few dozen kilometres or so. Up until now its size was only known within a range of some hundreds of kilometres! The observation of this occultation is the longest ever to have been carried out: a distance of 14 billion kilometres (three times as far as Pluto).
Emmanuël Jehin & others / TRAPPIST Observatory
http://www.skyandtelescope.com/news/106861063.html
E. Jehin, J. Manfroid, M. Gillon, D. Hutsemekers, and P. Magain, ?Occultation by (136169) Eris?, 2010 IAUC 9184.
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Images taken every 4,5 seconds clearly show the brief disappearance of a star behind the dwarf planet Eris on November 6, 2010 (Universal Time).
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4 November 2010: Comet Hartley2 observing campaign
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TRAPPIST is part of an international observing campaign to observe the Jupiter Family comet 103P/Hartley 2 that has just been flew by the NASA EPOXI spacecraft today.
Spectacular images have been sent to Earth by EPOXI showing strong jets coming from a very small (2km) pinut shape nucleus.
The many TRAPPIST observations through special filters that are collected every day during this period are used to derive the composition of the comet and to follow its activity.
A rotation period of the nulecus of 18.2 hours has been found as well as a braking of the rotation speed with time.
Jehin, E.; Manfroid, J.; Hutsemekers, D.; Gillon, M.; Magain, P, "Comet 103P/Hartley", 2010 CBET 2589
http://www.nasa.gov/mission_pages/epoxi/epoxi20101104b.html
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Comet 103P/Hartley2 on Oct. 31 through the various narrow band cometary filters (from left to right the images reveal the distribution of the radicals OH, CN, C3, C2, GC and the ion H2O+)
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8 June 2010: TRAPPIST First Light !
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Our new robotic telescope has had its first light at the European Southern Observatory's (ESO) La Silla Observatory in Chile last night. The TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST) is devoted to the study of planetary systems through two approaches: the detection and characterization of planets located outside the solar system (exoplanets), and the study of comets orbiting around the Sun. It is a 24-inch (60 centimeters) robotic telescope which is operated from a control room in Liege, Belgium, 12,000 kilometers away.
The first light was done from the Liège University downtown with Bernard Rentier the rector of the University, Didier Queloz from Geneva Observatory, the TRAPPIST team and journalists. Control of the telescope was taken and the first light has been done on the famous Tarentula Nebula in real time.
http://www.ulg.ac.be/cms/c_470567/trappist-va-brasser-le-ciel
http://www.eso.org/public/news/eso1023/
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TRAPPIST first light image of the Tarantula Nebula in the Large Magellanic Cloud.
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