The Tunguska Event--100 Years Later

The Tunguska Event--100 Years Later

June 30, 2008: The year is 1908, and it's just after seven in the morning. A man is sitting on the front porch of a trading post at Vanavara in Siberia. Little does he know, in a few moments, he will be hurled from his chair and the heat will be so intense he will feel as though his shirt is on fire.

That's how the Tunguska event felt 40 miles from ground zero.

Today, June 30, 2008, is the 100th anniversary of that ferocious impact near the Podkamennaya Tunguska River in remote Siberia--and after 100 years, scientists are still talking about it.

"If you want to start a conversation with anyone in the asteroid business all you have to say is Tunguska," says Don Yeomans, manager of the Near-Earth Object Office at NASA's Jet Propulsion Laboratory. "It is the only entry of a large meteoroid we have in the modern era with first-hand accounts."

Above: Trees felled by the Tunguska explosion. Credit: the Leonid Kulik Expedition. [more]

While the impact occurred in '08, the first scientific expedition to the area would have to wait for 19 years. In 1921, Leonid Kulik, the chief curator for the meteorite collection of the St. Petersburg museum led an expedition to Tunguska. But the harsh conditions of the Siberian outback thwarted his team's attempt to reach the area of the blast. In 1927, a new expedition, again lead by Kulik, reached its goal.

"At first, the locals were reluctant to tell Kulik about the event," said Yeomans. "They believed the blast was a visitation by the god Ogdy, who had cursed the area by smashing trees and killing animals."

While testimonials may have at first been difficult to obtain, there was plenty of evidence lying around. Eight hundred square miles of remote forest had been ripped asunder. Eighty million trees were on their sides, lying in a radial pattern.

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"Those trees acted as markers, pointing directly away from the blast's epicenter," said Yeomans. "Later, when the team arrived at ground zero, they found the trees there standing upright – but their limbs and bark had been stripped away. They looked like a forest of telephone poles."

Such debranching requires fast moving shock waves that break off a tree's branches before the branches can transfer the impact momentum to the tree's stem. Thirty seven years after the Tunguska blast, branchless trees would be found at the site of another massive explosion – Hiroshima, Japan.

Kulik's expeditions (he traveled to Tunguska on three separate occasions) did finally get some of the locals to talk. One was the man based at the Vanara trading post who witnessed the heat blast as he was launched from his chair. His account:

Suddenly in the north sky… the sky was split in two, and high above the forest the whole northern part of the sky appeared covered with fire… At that moment there was a bang in the sky and a mighty crash… The crash was followed by a noise like stones falling from the sky, or of guns firing. The earth trembled.

The massive explosion packed a wallop. The resulting seismic shockwave registered with sensitive barometers as far away as England. Dense clouds formed over the region at high altitudes which reflected sunlight from beyond the horizon. Night skies glowed, and reports came in that people who lived as far away as Asia could read newspapers outdoors as late as midnight. Locally, hundreds of reindeer, the livelihood of local herders, were killed, but there was no direct evidence that any person perished in the blast.

Above: The location of the Tunguska impact.

"A century later some still debate the cause and come up with different scenarios that could have caused the explosion," said Yeomans. "But the generally agreed upon theory is that on the morning of June 30, 1908, a large space rock, about 120 feet across, entered the atmosphere of Siberia and then detonated in the sky."

It is estimated the asteroid entered Earth's atmosphere traveling at a speed of about 33,500 miles per hour. During its quick plunge, the 220-million-pound space rock heated the air surrounding it to 44,500 degrees Fahrenheit. At 7:17 a.m. (local Siberia time), at a height of about 28,000 feet, the combination of pressure and heat caused the asteroid to fragment and annihilate itself, producing a fireball and releasing energy equivalent to about 185 Hiroshima bombs.

"That is why there is no impact crater," said Yeomans. "The great majority of the asteroid is consumed in the explosion."

Yeomans and his colleagues at JPL's Near-Earth Object Office are tasked with plotting the orbits of present-day comets and asteroids that cross Earth's path, and could be potentially hazardous to our planet. Yeomans estimates that, on average, a Tunguska-sized asteroid will enter Earth's atmosphere once every 300 years.

"From a scientific point of view, I think about Tunguska all the time," he admits. Putting it all in perspective, however, "the thought of another Tunguska does not keep me up at night."

Editor: Dr. Tony Phillips | Credit: Science@NASA

Yulvi Wrote :
Not yet analyze...

Si Kaki Besi Jadi Duta Universitas

Si Kaki Besi Jadi Duta Universitas

by Yulvianus Harjono

Tidak butuh waktu lama, hanya beberapa detik, petugas tersebut berhasil memadamkan api dari lilin di pojok sebuah labyrinth. Melewati gang-gang sempit, berkelok-kelok, dan rintangan menghadang. Beberapa detik kemudian, ia melakukan hal yang sama di pojok lainnya. Pekerjaan itu dituntaskan dengan sangat dingin, rapi, tetapi tanpa ekspresi.
Tahukah anda, petugas pemadam api itu sama sekali bukan manusia. Melainkan, sebuah prototipe robot cerdas yang dikembangkan di Laboratorium Robotika Universitas Komputer Indonesia (Unikom), Bandung. Robot-robot inilah merupakan duta pertaruhan nama besar lembaga perguruan tinggi di dalam Final Kontes Robot Cerdas Indonesia (KRCI) 2008 pada 14-15 Juni mendatang di Balairung Universitas Indonesia.
Sisa tiga minggu ini betul-betul sangat dimanfaatkan Tim Robotika Unikom untuk mempersiapkan diri dalam babak final nasional KRCI itu. Saat ditemui di laboratorium, Rabu (28/5) lalu, hampir seluruh anggota tim yang berjumlah 10 orang beserta dua dosen pembimbing hadir di sana. Sibuk mengotak-atik teknik dan strategi lomba nantinya.
Menurut Yusrila Y. Kerlooza, salah satu pembimbing, anggota tim bahkan sempat dikarantina (tidak boleh pulang) sejak beberapa pekan terakhir untuk persiapan. Tahun ini, tingkat kesulitan kompetisi diprediksi bakal lebih tinggi dari tahun sebelumnya. Baik dalam hal variasi medan serta tingkat rintangannya.
”Pada seleksi regional saja, di tempat lain, ada beberapa divisi yang tidak ada juara. Karena, tidak berhasil melewati treshold (batas),” tuturnya. Robot-robot cerdas ini punya kemampuan istimewa yaitu membaca arah, melewati rintangan, memadamkan api, hingga memindahkan benda sesuai yang diprogramkan. Kuncinya ada pada pembuatan alogaritma, yaitu kode program yang tersimpan di microprocessor robot. Fungsi, tugas, dan cara kendali robot bergantung pada alogaritma ini.
Satu unit robot ini bernilai investasi Rp 9 juta. Biaya risetnya dua kali lipatnya. Secara fisik, bentuknya seperti mobil tank mainan yang mampu berputar ke arah 360 derajat. Desain ini dikembangkan sendiri. Alatnya terdiri dari sensor ultrasonik (pembaca bentuk ruang), sensor infra merah, alat navigasi, sensor api (pembaca panas), processor (otak), dan motor (kendali) yang memiliki kontrol percepatan.
Menurut Yusrila, bisa saja prototipe robot ini nantinya dikembangkan menjadi pemadam kebakaran sungguhan. ”Kan tidak sedikit pemadam kebakaran yang meninggal akibat terkena reruntuhan (api). Keberadaan robot-robot ini bisa mengurangi resiko dari kematian ini,” ucapnya.
Tiga kampus dari Jabar
Unikom merupakan satu dari empat perguruan tinggi dari Jawa Barat yang lolos ke Final KRCI 2008. Tiga lainnya Institut Teknologi Bandung, Politeknik Bandung, dan Universitas Indonesia. Namun, hanya Unikom satu-satunya perguruan tinggi di Indonesia yang meloloskan wakilnya ke seluruh divisi (kategori) lomba yaitu Senior Beroda, Senior Berkaki, Expert Single, dan Expert Swarm. Keempat tim itu adalah Du 114-V8, NexT 116, iQrU-112, dan DU-102.
Wajarlah jika Rektor Unikom Eddy Soeryanto Soegoto optimis, keempat timnya mampu meraih gelar juara pada semua divisi di KRCI 2008 ini. Optimisme ini muncul mengingat gemilangnya prestasi tim robot Unikom pada seleksi tingkat Regional II (DKI Jakarta, Banten dan Jabar). Tim ini menyapu bersih perolehan juara pada empat kategori. Tahun lalu, Unikom berhasil merebut dua gelar juara pada Divisi Senior Beroda dan Senior Berkaki.
Eddy pun berjanji memberikan penghargaan khusus berupa beasiswa dan fasilitas pendidikan lainnya bagi mahasiswa dan dosen yang sukses mengantarkan tim ini sebagai juara. Sejak 2005, robotika menjadi salah satu kelompok keahlian unggulan di Unikom. Di kampus ini didirikan pula unit kegiatan mahasiswa bernama Divisi Robotika dan kini menjadi salah satu UKM favorit mahasiswa. Bahkan, laboratorium ini dilindungi dengan akses kontrol. Hanya pemegang akses saja yang bisa masuk.(Kompas Daily Copyright, Publish @ 30/5/2008))

Phoenix probe's descent to Mars

Orbiter captures Phoenix probe's descent to Mars

By Irene Klotz

PASADENA, California (Reuters) - A sharp-eyed Mars orbiter snapped an image of sister probe Phoenix descending through Martian skies toward a polar landing site to search for water and assess conditions for life, mission managers said on Monday.

Phoenix touched down at 4:53 p.m. PDT (7:53 p.m. EDT/2353 GMT) on Sunday, becoming the first spacecraft to reach a polar region of Mars. Problems during descent doomed NASA's first polar lander in 1999.

The unprecedented image, taken by the Mars Reconnaissance Orbiter as a result of careful planning and good luck, shows the small probe dangling beneath its parachute.

Features of the planet's face, including polygon-shaped patterns in the frozen arctic soil, can be seen faintly in the background.

The shapes are of interest to scientists who plan to use Phoenix to dig beneath what is expected to be a thin layer of soil to sample underlying ice. They want to learn if the water was ever liquid, which is believed to be necessary for life.

So far, the Phoenix science team has had only a tantalizing glimpse of the landing site from an onboard camera that has completed only a low-resolution sliver of a planned 360-degree panoramic image.

The probe is using two satellites -- Mars Reconnaissance Orbiter and Mars Odyssey -- to communicate with controllers on Earth.

"We're particularly interested in seeing what's in our digging area," lead scientist Peter Smith told reporters at the Jet Propulsion Laboratory in Pasadena, which oversees the mission.

Cracks in the ground are a sign of changes in underlying ice, Smith said. Scientists believe the cracks are fresh because they are not covered with the fine red dust that permeates Mars' atmosphere.

Checks on Phoenix science instruments and an assessment of the landing site will continue throughout the week. Science operations, which are being overseen by the University of Arizona in Tucson, are expected to begin in June.

Phoenix completed a 10-month, 420-million-mile (676-million-km) voyage from Earth with a do-or-die plunge through the Mars atmosphere and a safe touchdown in the northern Arctic circle.

Over the next three months, scientists want to bore into the ground and study water and soil samples to determine if conditions were suitable to support life.

In addition to determining if the water was ever liquid, scientists want to find out if it holds any organic matter.

The Viking landers in the 1970s and early 1980s conducted similar tests on surface soils. Scientists later determined solar radiation, which flows virtually unimpeded by the planet's thin atmosphere, creates a sterile environment as it bombards the ground.

Subsurface conditions, however, might provide habitats for microbes and bacterial life to flourish on Mars, as they do in extreme environments on Earth.

For the past decade, NASA has been searching for signs of past water on Mars with a fleet of orbiters and a pair of rovers on the ground. The detection of subsurface frozen water in 2002 by Mars Odyssey prompted scientists to propose the Phoenix mission to investigate.

(Editing by Eric Walsh)

Source : Reuters

No Yulvi Wrote this time...Give it to the Pro...

Iptek
Ninok Leksono
PHOENIX DAN KESENJANGAN BUMI-LANGIT

"Hanya lima dari 11 upaya pendaratan (wahana dari) planet kita di
Planet Merah (Mars) yang berhasil. Dalam mengeksplorasi alam semesta,
kita menerima risiko (tersebut) sebagai ganti dari imbalan ilmiah
besar." Ed Weiler, Wakil Administratur NASA (www.nasa.gov).
Setelah melanglang semesta sejauh hampir 700.000.000 kilometer,
wahana antariksa Phoenix, yang diluncurkan 4 Agustus 2007, Senin
(26/5) pagi WIB mendarat di Planet Mars. Phoenix-dari nama burung
perkasa dalam mitologi-mendarat di kutub utara Mars untuk menguji satu
lokasi yang diduga menyimpan air beku yang bisa dijangkau oleh lengan
robotnya.
Inilah prestasi antariksa yang kembali ditorehkan AS. Meski misi
ke Mars bukan yang pertama, misi kali ini memiliki kerumitan
tersendiri. Phoenix lolos setelah harus melalui fase akhir sebelum
mendarat (descent) yang tidak mudah.
Phoenix segera mengirimkan berita melalui sinyal radio ke Bumi.
Sinyal berkecepatan cahaya 300.000 kilometer per detik perlu sekitar
15 menit untuk menempuh jarak dari Mars keBumi setelah direlai via
wahana orbit Mars Odyssey. Di Bumi, sinyal diterima di stasiun antena
Deep Space Network, Goldstone, California.
Inilah pertama kalinya dalam 32 tahun, juga ketiga kalinya dalam
sejarah, tim dari Jet Propulsion Laboratory (JPL) yang berpusat di
Pasadena, Californa, berhasil mendaratkan secara mulus wahana
antariksa di Mars, kata Administratur NASA Michael Griffin. Pendaratan
terakhir adalah Viking 2 pada tahun 1976. Selain JPL yang dikelola
NASA, pihak lain di AS yang ambil bagian dalam misi kali ini adalah
Lockheed Martin Space Systems di Denver dan University of Arizona di
Tucson.
Selama penerbangan ratusan juta kilometer dari Bumi, Phoenix
mengandalkan kebutuhan listrik pada tingkat (roket) jelajah. Roket ini
dilepaskan tujuh menit sebelum wahana pendarat Phoenix yang dibungkus
dalam selubung pelindung panas memasuki atmosfer Mars. Sejak itu
kebutuhan listrik ditanggung baterai sampai sepasang panelsurya milik
Phoenix direntangkan.
"Pendaratan yang menggetarkan!," kata Peter Smith, penanggung
jawab utama misi Phoenix dari University of Arizona. Namun, setelah
pendaratan masih harus dipastikan bahwa lengan robot sepanjang 2,5
meter yang dibutuhkan untuk mengambil contoh tanah dan es untuk
diteliti bisa dioperasikan.
Komitmen antariksa
Keberhasilan Phoenix menegaskan, meski ada pelbagai problem dunia,
seperti minyak dan pangan, yang dihadapi umat manusia hari-hari ini,
komitmen penelitian antariksa terbukti tidak surut. Negara-negara maju-
sesuai kemampuan masing-masing-tidak ingin ketinggalan dalam ikhtiar
mencari jawab teka-teki semesta dan kehidupan.
Menyusul penemuan wahana Mars Odyssey pada tahun 2002 tentang air
beku di kawasan lintang tinggi Mars, muncul ide untuk menyelidiki hal
itu lebih dalam. Phoenix adalah jawabannya. Itu sebabnya, wahana
pendarat ini dilengkapi dengan instrumen ilmiah untuk memastikan dalam
tiga bulan ke depan, apakah es di bawah permukaan pernah mencair dan
apakah sejumlah bahan kimia yang menjadi bahan baku kehidupan bisa
lestari di tanah beku.
Itu, menurut JPL NASA, merupakan pertanyaan kunci dalam
mengevaluasi apakah lingkungan di Mars selama ini cocok (favorable)
untuk menopang kehidupan tingkat mikrobial.
Ditempatkan dalam kerangka lebih luas, mencari kehidupan luar
Bumi, seolah menjadi upaya kodrati umat manusia yangingin mendapat
konfirmasi apakah dirinya satu-satunya kehidupan cerdas di alam
semesta. Boleh jadi umat manusia sejauh ini berada dalam situasi yang
mudah membawanya dalam dua sikap berlawanan. Pada satu sisi, planet
yang bisa menopang kehidupan seperti yang ada di Bumi amat langka,
bisa jadi pula satu-satunya, di alam semesta.
Pada sisi lain, pandangan itu bisa terasa arogan mengingat di alam
semesta ada triliunan bintang sehingga terlalu dini untuk menyimpulkan
tidak ada kehidupan cerdas di planet lain.
Untuk menjawab pertanyaan fundamental-dan bahkan filosofis
tersebut-dibutuhkan dedikasi dan investasi. AS, juga negara maju lain,
mengeluarkan dana miliaran dollar untuk membangun stasiun angkasa ISS
untuk basis penelitian antariksa jauh. Untuk Mars, AS bahkan
mempersiapkan eksplorasi selama bertahun-tahun, mengumpulkan data dan
informasi dari wahana yang diluncurkan sebelum ini, yakni Mars Odyssey
dan Mars Reconnaissance Orbiter. Dana memang banyak dibutuhkan. Untuk
misi Phoenix saja biayanya 386 juta dollar AS, atau sekitar Rp 3,6
triliun (Leonard David, Space.com, 10/1/2007).
Tantangan teknologi dan finansial selalu saja terjawab. Visi
mengenai tantangan masa depan umat manusia ikut membentuk munculnya
kebijakan yang tampaknya tidak dikaitkan urusan hidup sehari-hari di
atas.

Kesenjangan bumi-langit
AS dalam misi Phoenix menggalang kerja sama luas mengingat
kompleksnya teknologi yang terlibat dan luasnya cakupan misi. Selain
ketiga lembaga di AS, masih ada Kanada (Canadian Space Agency) yang
memasok stasiun cuaca bagi Phoenix, yang juga diharapkan memberikan
info tentang perubahan iklim yang diduga pernah terjadi di Mars. Juga
Universitas Neuchatel, Swiss; juga ada Universitas Copenhagen dan
Aarhus, Denmark; Institut Max Planck, Jerman; dan Institut Meteorologi
Finlandia.
Untuk urusan ilmu pengetahuan, umat manusia sering dapat bersatu,
bekerja sama menjawab tantangan bersama. Dengan upaya semacam itu,
sejauh ini telah dicapai prestasi ilmiah besar di berbagai bidang
sains.
Ketika manusia kini dihadapkan pada tantangan survival yang tak
ringan, khususnya soal pangan, energi, dan lingkungan hidup, semangat
kerja sama itu pula yang seharusnya mewarnai upaya manusia. Namun,
tampaknya justru di bidang-bidang di atas manusia memperlihatkan
egoisme nasionalistik.
Pada sisi lain, meskipun kerja sama ilmiah tampak lebih mudah
dibangun di bidang antariksa, tingkat kemampuan yang ada bisa
diibaratkan antara bumi dan langit. Negara berkembang seperti
Indonesia tentu saja sekarang ini hanya bisa melihat dengan takjub
bahwa justru ketika ia sedang dihadapkan pada urusan kebutuhan dasar,
negara maju berhasil mendaratkan wahananya di Planet Mars.
Tanpa melupakan langkah-langkah yang dibuat Lembaga Penerbangan
dan Antariksa Nasional (Lapan), kita melihat dengan gamblang
kesenjangan itu, betapa negara adidaya AS telah mencapai penguasaan
iptek antariksa yang sedemikian jauhnya, sementara kita belum beranjak
dari urusan pemenuhan kebutuhan dasar.

Source : Kompas Daily, Wednesday, May 28, 2008.

Phoenix Lands on Mars!

Phoenix Lands on Mars!

May 25, 2008: NASA's Phoenix spacecraft landed in the northern polar region of Mars Sunday to begin three months of examining a site chosen for its likelihood of having frozen water within reach of the lander's robotic arm.

Radio signals received at 4:53:44 p.m. Pacific Time (7:53:44 p.m. Eastern Time) confirmed the Phoenix Mars Lander had survived its difficult final descent and touchdown 15 minutes earlier. The signals took that long to travel from Mars to Earth at the speed of light.

Mission team members at NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Lockheed Martin Space Systems, Denver; and the University of Arizona, Tucson, cheered confirmation of the landing and eagerly awaited further information from Phoenix later Sunday night.

Among those in the JPL control room was NASA Administrator Michael Griffin, who noted this was the first successful Mars landing without airbags since Viking 2 in 1976.

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"For the first time in 32 years, and only the third time in history, a JPL team has carried out a soft landing on Mars," Griffin said. "I couldn't be happier to be here to witness this incredible achievement."

During its 422-million-mile flight from Earth to Mars after launching on Aug. 4, 2007, Phoenix relied on electricity from solar panels. The cruise stage with those solar panels was jettisoned seven minutes before the lander, encased in a protective shell, entered the Martian atmosphere. Batteries will now provide electricity until the lander's own pair of solar arrays spread open.

"We've passed the hardest part and we're breathing again, but we still need to see that Phoenix has opened its solar arrays and begun generating power," said JPL's Barry Goldstein, the Phoenix project manager. If all goes well, engineers will learn the status of the solar arrays between 7 and 7:30 p.m. Pacific Time from a Phoenix transmission relayed via NASA's Mars Odyssey orbiter.

[Update: The solar arrays have deployed!]

Above: First pictures beamed back to Earth from Phoenix's arctic landing site. Image credits: NASA/JPL-Calech/University of Arizona. [more]

The team will also be watching for the Sunday night transmission to confirm that masts for the stereo camera and the weather station have swung to their vertical positions.

[Update: The stereo camera and weather station have swung to their vertical positions.]

"What a thrilling landing! But the team is waiting impatiently for the next set of signals that will verify a healthy spacecraft," said Peter Smith of the University of Arizona, principal investigator for the Phoenix mission. "I can hardly contain my enthusiasm. The first landed images of the Martian polar terrain will set the stage for our mission."

Another critical deployment will be the first use of the 7.7-foot-long robotic arm on Phoenix, which will not be attempted for at least two days. Researchers will use the arm during future weeks to get samples of soil and ice into laboratory instruments on the lander deck.

The signal confirming that Phoenix had survived touchdown was relayed via Mars Odyssey and received on Earth at the Goldstone, Calif., antenna station of NASA's Deep Space Network.

Check http://www.nasa.gov/phoenix for updates.

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Editor: Dr. Tony Phillips | Credit: Science@NASA

more information

Phoenix --mission home page Phoenix uses hardware from a spacecraft built for a 2001 launch that was canceled in response to the loss of a similar Mars spacecraft during a 1999 landing attempt. Researchers who proposed the Phoenix mission in 2002 saw the unused spacecraft as a resource for pursuing a new science opportunity. Earlier in 2002, Mars Odyssey discovered that plentiful water ice lies just beneath the surface throughout much of high-latitude Mars. NASA chose the Phoenix proposal over 24 other proposals to become the first endeavor in the Mars Scout program of competitively selected missions. The Phoenix mission is led by Smith at the University of Arizona with project management at JPL and development partnership at Lockheed Martin, Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute.

Baby Supernova in Our Neighborhood

Baby Supernova in Our Neighborhood

WASHINGTON, May 14 - A baby supernova, just over
a century old, has been found in the middle of our own Milky
Way galaxy and provides an unprecedented opportunity to watch a
star dying, astronomers said on Wednesday.
The supernova, known as G1.9+0.3, would have made a bright
flash when it first exploded 140 years ago but was not seen
because dust obscures it, David Green of Britain’s University
of Cambridge and colleagues reported.
“It’s by far the youngest supernova identified in the
galaxy,” Green told reporters in a telephone briefing.
Green first identified the object in 1985 as a possible
supernova, using radio readings from the U.S. National Science
Foundation’s Very Large Array.
In 2007, Stephen Reynolds of North Carolina State
University and colleagues looked at it using the orbiting
Chandra X-Ray Observatory. They were surprised to find it was
16 percent bigger than the radio measurements.
“The only reasonable explanation we could come up with was,
in the 22 years between those observations, it had grown by
that rate,” Reynolds said.
They extrapolated its rate of growth to date the original
explosion at 140 years ago.
The supernova is at the center of the galaxy, roughly
25,000 light-years from Earth. A light-year is the distance
light travels in one year — about 5.8 trillion miles (9.5
trillion km).
Reynolds says the discovery renews the question of why so
few supernovae have been seen in the Milky Way. Based on other
galaxies, astronomers have estimated that about three such
stellar explosions should occur every century.
The most recent supernova in Earth’s neighborhood known
until now occurred around 1680, creating the remnant called
Cassiopeia A.
“If the supernova rate estimates are correct, there should
be the remnants of about 10 supernova explosions in the Milky
Way that are younger than Cassiopeia A,” said Green.
“It’s great to finally track one of them down.”
Dust could be hiding most of them, Green and Reynolds said,
but X-ray and radio observations might find them.
“Looking out of the Milky Way, we can see some supernova
explosions with optical telescopes across half of the Universe,
but when they’re in this murk, we can miss them in our own
cosmic back yard,” Reynolds said.
Writing in the Astrophysical Journal Letters and Monthly
Notices of the Royal Astronomical Society, the researchers said
they can now watch and analyze the explosion as it unfolds.
While more distant supernovae can be seen with the naked
eye, they quickly fade and the radio waves they create will
take centuries to arrive.
Dr. Robert Kirshner of the Harvard Smithsonian Center for
Astrophysics, who did not work on the study, said studying a
young supernova could help scientists understand the very
beginnings of life.
“The supernova makes a chemical element through real
alchemy — transforming one element into another one,” Kirshner
said.
The iron in blood, for instance, was made by a star.
“We are all stardust and it seems reasonable for us to want
to know how these elements get formed when stars explode,”
Kirshner added.
“Our planet, our cells, our pieces are made of the vanished
ashes of these exploded supernovae ... You are actually getting
to see the rock that made the splash, not the wave that is
going out into the pond.”(REUTERS)

CAPE CANAVERAL, Florida (AP) — Astronomers have discovered the
youngest known supernova in the Milky Way galaxy, still just a baby
at 140 years old.
The scientists, who announced their findings Wednesday, used a
radio observatory in New Mexico and NASA’s Chandra X-ray Observatory
in space to identify when the supernova, or stellar explosion,
occurred. They put the star-dying event at some time around 1868.
Before now, the youngest supernova in the Milky Way was thought
to have occurred around 1680.
A supernova is the catastrophic explosion of a star that releases
an extraordinary amount of energy, enough to outshine an entire
galaxy.
The new baby supernova is located near the center of the galaxy
and obscured by dense gas and dust, making it virtually impossible
to see in optical light.
Two to three supernovae are thought to occur every century in the
Milky Way. As a result, there are probably even younger ones out
there waiting to be identified, said David Green of the University
of Cambridge in England, who led the radio observatory study.
Green and others have been tracking the remnant of the supernova
since 1985 via the National Science Foundation’s Very Large Array, a
radio astronomy observatory. But it was not until last year that a
team led by North Carolina State University physicist Stephen
Reynolds found with help from Chandra how much the remnant had
expanded. That indicated the supernova was much younger than initial
estimates ranging from 400 to 1,000 years old.
The Very Large Array made new observations in March and helped
pinpoint the age at 140 years, possibly less if the expansion has
been slowing.
“It’s the combination of the radio and the X-ray, the older
technique and the new one, that tells us what this object really is.
So you get a lot more when you put all of these clues together,”
said Robert Kirshner, a Harvard University astronomer who is not
affiliated with the study.
“It’s a little like one of those shows on TV where they
investigate a death. This is a stellar death, all right, and the
corpse is still warm,” Kirshner said during a teleconference with
reporters.
Astronomers typically observe supernova remnants that are 10,000
or so years old, not relative infants like this one. Getting the
total picture, from the start, is important in figuring out how
often supernovae explode in the Milky Way.
In this case, “you’re actually getting to see the rock that made
the splash, not the wave that’s going out into the pond,” Kirshner
said.(Associated Press Aerospace Writter)

Youngest supernova in Milky Way
by Jean-Louis Santini


WASHINGTON, May 14, 2008 (AFP) - Astronomers have discovered the most recent supernova in our Milky Way, hoping it will further knowledge about the spectacular stellar explosions and the workings of our galaxy, a research paper said Wednesday.
Named G1.9+0.3, the supernova in the constellation Sagitarius is some 140 years old and was detected through radio and X-ray telescopes, since the original, dazzling explosion was hidden from view by a dense field of gas and dust near the galaxy center, where it took place.
It is about 200 years younger than Cassiopeia A, the last known Milky Way supernova that exploded around 1680. Age estimates are based on the rate of expansion of the supernova remains — the faster the expansion the more recent the explosion.
Stephen Reynolds of North Carolina State University in Raleigh, who led the study, said the new supernova was first noticed by astronomers more than 20 years ago, when the original explosion was estimated to have happened 400-1,000 years ago.
Its more recent origin became apparent, he said, when images of the object taken in 2007 through NASA’s Chandra X-ray Observatory were compared with the 1985 images of the National Radio Astronomy Observatory’s Very Large Array, which also belongs to NASA.
In the intervening 22 years, Reynolds said, the supernova remnants had expanded about 16 percent, indicating that they were much younger than previously thought.
Measurements taken earlier this year by the Very Large Array confirmed the age of the supernova remains at 140 years, possibly less if the expansion has been slowing down, making it the youngest on record in the Milky Way, the astrophysicist said.
With an unobstructed view, had the supernova not taken place near the center of the galaxy, the stellar explosion would have been visible in 1870-1900 in Sagittarius and probably taken for a new star, he explained.
“We can see some supernova explosions with optical telescopes across half of the universe, but when they’re in this murk we can miss them in our own cosmic backyard,” Reynolds said in a telephone press conference.
“Fortunately, the expanding gas cloud from the explosion shines brightly in radio waves and X-rays for thousands of years. X-ray and radio telescopes can see through all that obscuration and show us what we’ve been missing.” He said astronomers normally observe ancient supernova remnants with small rates in expansion that are very difficult to measure.
The remains of the galaxy’s most recent supernova are very brilliant and should afford astronomers keener insight into the phenomenon and its effects on the surrounding galaxy, Reynolds said.
“No other object in the galaxy has properties like this,” he said. “This find is extremely important for learning more about how some stars explode and what happens in the aftermath.” Supernovae occur when stars run out of nuclear fuel and explode, providing crucial information about the universe’s history.
They heat and redistribute large amounts of gas, and pump heavy elements out into their surroundings and can trigger the formation of new stars as part of a cycle of stellar death and rebirth.
The explosion also can leave behind, in addition to the expanding remnant, a central neutron star or black hole.
A rare occurrence in the span of a human lifetime, supernovae are estimated to happen about three times per century in the Milky Way.
“If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions that are younger than Cassiopeia A,” said David Green of the University of Cambridge in the United Kingdom, who led the Very Large Array study.
“It’s great to finally track one of them down.” The study is published in the January 10 issue of The Astrophysical Journal Letters.
(js/fgf/ch US-astronomy-supernova AFP)

Yulvi Write :

Sungguh sangat tersentak ketika pagi ini saya membuka wirenews dari Kompas Wire Services, Kamis (15/5) ini. Di tengah dominasi berita domestik yang masih saja diwarnai isu kenaikan bahan bakar minyak (BBM) dan kebijakan bodoh Bantuan Langsung Tunai-nya pemerintah, dimana HL berita internasional masih menyoroti seputar gempa di China, mata dan pikiran saya justru tersita pada berita ini:"Baby Supernova in Our Neighborhood" yang diberitakan ramai oleh Reuters, AP, dan AFP. Bagi sebagian orang, mungkin ini tidak menarik. Tetapi,tidak demikian halnya bagi saya yang menyukai sains dan astronomi.
Adalah David Green dari Universitas Cambridge yang membuat penemuan heboh ini. Penelusurannya selama 15 tahun tentang dugaan keberadaan supernova termuda di Galaksi Bimasakti, sistem galaksi tempat bumi berpijak, terjawab sudah. G1.9+0.3, demikian nama supernova muda yang terletak di pusat Bimasakti itu. Ia berjarak 25.000 tahun cahaya dari Bumi...
Yang sungguh mengejutkan, kenapa dijuluki muda, karena berdasarkan pengamatan U.S. National Science Foundation’s Very Large Array (1985) hingga Stephen Reynolds dari North Carolina State University menggunakan piranti Chandra X-Ray Observatory (2007), umur supernova itu baru 140 tahun!!! Ledakan bintang mati ini diprediksi terjadi pada 1868....Seperti dilaporkan AFP, usianya jauh lebih muda dari penemuan terakhir supernova di Galaksi Bimasakti, tahun 1680....
Penemuan ini tentu menjadi tonggak sejarah baru dalam babak pengungkapan misteri supernova yang hingga kini masih belum banyak tersingkap...Menjadi modal berharga bagi para ilmuwan untuk mengungkap teori mati dan lahirnya bintang, pembentukan lubang hitam (blackhole) , dan tentu bisa jadi, teori pembentukan alam semesta....
Apalagi,letak dan peristiwa kejadiannya sangat berdekatan...Mari kita tunggu kabar dan kejutan berikutnya!!!!
viva sains