June 16, 2008
Today, at an international conference, a team of European astronomers announced a remarkable breakthrough in the field of extra-solar planets. Using the HARPS instrument at the ESO La Silla Observatory, they have found a triple system of super-Earths around the star HD 40307. Moreover, looking at their entire sample studied with HARPS, the astronomers count a total of 45 candidate planets with a mass below 30 Earth masses and an orbital period shorter than 50 days. This implies that one solar-like star out of three harbours such planets.

"Does every single star harbour planets and, if yes, how many?"
wonders planet hunter Michel Mayor from Geneva Observatory. "We may not yet know the answer but we are making huge progress towards it."

Since the discovery in 1995 of a planet around the star 51 Pegasi by Mayor and Didier Queloz, more than 270 exoplanets have been found, mostly around solar-like stars. Most of these planets are giants, such as Jupiter or Saturn, and current statistics show that about 1 out of
14 stars harbours this kind of planet.

"With the advent of much more precise instruments such as the HARPS spectrograph on ESO's 3.6-m telescope at La Silla, we can now discover smaller planets, with masses between 2 and 10 times the Earth's mass,"
says Stephane Udry, one of Mayor's colleagues. Such planets are called super-Earths, as they are more massive than the Earth but less massive than Uranus and Neptune (about 15 Earth masses).

The group of astronomers have now discovered a system of three super-Earths around a rather normal star, which is slightly less massive than our Sun, and is located 42 light-years away towards the southern Doradus and Pictor constellations.

"We have made very precise measurements of the velocity of the star HD
40307 over the last five years, which clearly reveal the presence of three planets," says Mayor.

The planets, having 4.2, 6.7, and 9.4 times the mass of the Earth, orbit the star with periods of 4.3, 9.6, and 20.4 days, respectively.

"The perturbations induced by the planets are really tiny - the mass of the smallest planets is one hundred thousand times smaller than that of the star - and only the high sensitivity of HARPS made it possible to detect them," says co-author Francois Bouchy, from the Institut d'Astrophysique de Paris, France.

Indeed, each planet induces a motion of the star of only a few metres per second.

At the same conference, the team of astronomers announced the discovery of two other planetary systems, also with the HARPS spectrograph. In one, a super-Earth (7.5 Earth masses) orbits the star HD 181433 in 9.5 days. This star also hosts a Jupiter-like planet with a period close to 3 years. The second system contains a 22 Earth-mass planet having a period of 4 days and a Saturn-like planet with a 3-year period as well.

"Clearly these planets are only the tip of the iceberg," says Mayor.
"The analysis of all the stars studied with HARPS shows that about one third of all solar-like stars have either super-Earth or Neptune-like planets with orbital periods shorter than 50 days."

A planet in a tight, short-period orbit is indeed easier to find than one in a wide, long-period orbit.

"It is most probable that there are many other planets present: not only super-Earth and Neptune-like planets with longer periods, but also Earth-like planets that we cannot detect yet. Add to it the Jupiter-like planets already known, and you may well arrive at the conclusion that planets are ubiquitous," concludes Udry.


source by www.astronomy.com

New Mineral

NASA researchers and scientists from the United States, Germany and Japan have found a new mineral in material that likely came from a comet.

The mineral, a manganese silicide named Brownleeite, was discovered within an interplanetary dust particle, or IDP, that appears to have originated from comet 26P/Grigg-Skjellerup. The comet originally was discovered in 1902 and reappears every 5 years. The team that made the discovery is headed by Keiko Nakamura-Messenger, a space scientist at NASA's Johnson Space Center in Houston.

"When I saw this mineral for the first time, I immediately knew this was something no one had seen before," says Nakamura-Messenger. "But it took several more months to obtain conclusive data because these mineral grains were only 1/10,000 of an inch in size."

A new method of collecting IDPs was suggested by Scott Messenger, another Johnson space scientist. He predicted comet 26P/Grigg-Skjellerup was a source of dust grains that could be captured in Earth's stratosphere at a specific time of the year.

In response to his prediction, NASA performed stratospheric dust collections, using an ER-2 high-altitude aircraft flown from NASA's Dryden Flight Research Center at Edwards Air Force Base in California. The aircraft collected IDPs from this particular comet stream in April 2003. The new mineral was found in one of the particles. To determine the mineral's origin and examine other dust materials, a powerful new transmission electron microscope was installed in 2005 at Johnson.

"Because of their exceedingly tiny size, we had to use state-of-the-art nano-analysis techniques in the microscope to measure the chemical composition and crystal structure of Keiko's new mineral," says Lindsay Keller, Johnson space scientist and a co-discoverer of the new mineral. "This is a highly unusual material that has not been predicted either to be a cometary component or to have formed by condensation in the solar nebula."

Since 1982, NASA routinely has collected cosmic and interplanetary dust with high-altitude research aircraft. However, the sources of most dust particles have been difficult to pin down because of their complex histories in space. The Earth accretes about 40,000 tons of dust particles from space each year, originating mostly from disintegrating comets and asteroid collisions. This dust is a subject of intense interest because it is made of the original building blocks of our solar system, planets, and our bodies.

The mineral was surrounded by multiple layers of other minerals that have also been reported only in extraterrestrial rocks. There have been 4,324 minerals identified by the International Mineralogical Association, or IMA. This find adds one more mineral to that list.

The IMA-approved new mineral, Brownleeite, is named after Donald E. Brownlee, professor of astronomy at the University of Washington, Seattle. Brownlee founded the field of IP research. The understanding of the early solar system established from IDP studies would not exist without his efforts. Brownlee also is the principal investigator of NASA's Stardust mission.

Foto terbaru daripada planet Marikh merupakan sesuatu yang cukup bersejarah. Belum pernah sepanjang lebih 50 tahun penerokaan angkasa lepas, sebuah kapal angkasa merakam gambar sebuah lagi kapal angkasa yang sedang mendarat di sebuah planet lain. Sehinggalah Ahad lepas, apabila kamera canggih HiRISE di atas kapal angkasa Mars Reconnaissance Orbiter telah merakam Phoenix sedang perlahan-lahan mendarat menggunakan payung terjun.

Apa yang lebih menakjubkan dengan foto tersebut ialah kehadiran sebuah kawah besar bersaiz 10km di 'belakang' Phoenix, seolah-olah memberi gambaran bahawa kapal angkasa tersebut sedang menuju ke dalam kawah tersebut. Ini sebenarnya hanya sebuah ilusi optikal, yang mana jarak antara Phoenix dan kawah tersebut adalah sejauh 20km.

Subhanallah!

-enc shahrin .falakonline.net

The Astronomy Club

Assalamualaikum,

Di dalam kesempatan ini saya ingin menjemput tuan2 dan puan2 untuk masuk ke dalam club astronomy yang baru dilancarkan. Kami dengan khidmat seorang guru yang professional mewujudkan kelab ini di atas ilham dr ariza mohamed. Saya ingin sekali lagi menjemput tuan2 dan puan2 bersama anak2 untuk sama2 menikmati keindahan alam semesta yang dicipta oleh Tuhan sekalian alam untuk kita tinggal di dalamnya dan berfikir tentangnya. Di dalam kelab ini kita akan dapat melihat betapa kecilnya kita di alam Tuhan yang luas ini. Kita dipinjamkan bumi ini lalu kita merosakkannya, itulah hakikat manusia ini. InsyaAllah dengan kita mempelajari ilmu alam ini, kita akan dapat kembali semula ke jalan yang benar dan kita akan sedar betapa kecilnya diri kita ini. Dalam kesempatan ini saya sekali lagi menyeru tuan2 dan puan2 bersama dengan keluarga turut mengikuti program ini kerana kami tidak mahu hanya kami sahaja yang tahu tentang ilmu alam ini, tetapi kami mahu seluruh umat nabi Muhammad untuk tahu dan mengikuti program ini.


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