Fotografije planeta drugog sunca

HR 8799 planetarni sistem



The three exoplanets (red dots in the right panel) are shown orbiting HR 8799, whose residual light is shown as the multi-colored specks in the center of the right panel. An infrared image of one of the planets, which lies at 38 AU from the star, is shown in the right panel. Credit: National Research Council Canada.


Three exoplanets orbiting the same star have been imaged directly


A to-scale comparison of the HR 8799 system and our own

"I nearly had a heart attack at the end of May when I confirmed that Fomalhaut b orbits its parent star," Dr Kalas said. "It´s a profound and overwhelming experience to lay eyes on a planet never before seen."

Christian Marois of the Herzberg Institute for Astrophysics, Canada, and his team used the Keck and Gemini telescopes in Hawaii to look near a star called HR 8799, which is just visible to the naked eye.

The team studied light in the infrared part of the spectrum, hoping to spot planets that were still hot from their formation.

What they found in 2004, and confirmed again this year, are three planets circling the star.

According to a theoretical model that accounts for the light coming from the planets, they range in size from five to 13 times the mass of Jupiter and are probably only about 60 million years old.

The trio have similarities with our own Solar System. Their orbits are comparable in size to those of the outer planets, and the smaller planets are those closest to the Sun - again suggesting a system that formed through accretion.

Dr Marois points out that the current methods used in the exoplanet hunt are sensitive primarily to Jupiter-sized planets and larger.

"We thus do not have a full picture," he told BBC News. "The detection of the three planets around HR 8799 does not mean that no planets are orbiting at smaller separations. Other gas giant or even rocky planets could reside there."


http://www.space.com/scienceastronomy/081113-hubble-exoplanet.html
http://news.bbc.co.uk/1/hi/sci/tech/7725584.stm

U sljedecih nekoliko sumraka moci cete vidjeti tri planete. Najsjajnija, kao i uvijek, ce biti Venera visoko na nebu dok ce blize horizontu, pola sata nakon zalaska Sunca, biti uocljivi Merkur i Jupiter. Merkur ce biti par stepeni vise od Jupitera. Naravno, sve je ovo vidljivo golim okom i ono sto je najzanimljivije kada su tri planete vidljive je to da se tada jasno uocava ravan suncevog sustava po kojoj kruze planete (povucite zamisljenu liniju koja povezuje ove tri planete preko neba i dobit cete suncev disk).

Pozdrav...

citat:

---

NIN wrote:
U sljedecih nekoliko sumraka moci cete vidjeti tri planete. Najsjajnija, kao i uvijek, ce biti Venera visoko na nebu dok ce blize horizontu, pola sata nakon zalaska Sunca, biti uocljivi Merkur i Jupiter. Merkur ce biti par stepeni vise od Jupitera. Naravno, sve je ovo vidljivo golim okom i ono sto je najzanimljivije kada su tri planete vidljive je to da se tada jasno uocava ravan suncevog sustava po kojoj kruze planete (povucite zamisljenu liniju koja povezuje ove tri planete preko neba i dobit cete suncev disk).

Pozdrav...

---

citat:

---

Bosnjo wrote:


Btw, uvijek me zanimalo zasto planete kruze u ravni a ne u nekoj proizvoljnoj konfiguraciji. Ako moze kakvo objasnjenje in plain english, cijenio bih to...

---

Gamma-ray Flare Star




February 10, 2009: NASA´s Swift and Fermi spacecraft are monitoring a neutron star 30,000 light years from Earth that is drawing attention to itself with a series of powerful gamma-ray flares.


see caption"At times, this remarkable object has erupted with more than a hundred flares in as little as 20 minutes," said Loredana Vetere, who is coordinating the Swift observations at Pennsylvania State University. "The most intense flares emitted more total energy than the sun does in 20 years."

Right: An artist´s concept of the flare star in action. Credit: NASA/Goddard Space Flight Center Conceptual Image Lab. [more]

The star, known as SGR J1550-5418, lies in the southern constellation Norma. It began a series of modest eruptions on Oct. 3, 2008, settled down for a while, then roared back to life on Jan. 22, 2009, with an intense episode.

Because of its rapid-fire outbursts and gamma-ray spectrum, astronomers classify the object as a "soft-gamma-ray repeater" -- only the sixth known. In 2004, a giant flare from another soft-gamma-ray repeater was so intense it ionized Earth´s upper atmosphere from 50,000 light-years away: more.

Using data from an X-ray telescope onboard Swift, Jules Halpern at Columbia University captured the first "light echoes" ever seen from a soft-gamma-ray repeater. Images acquired when the latest flaring episode began show what appear to be expanding halos around the source. Multiple rings form as X-rays interact with dust clouds at different distances. Click on the image to play a 6-day movie:



Above: Swift´s X-Ray Telescope (XRT) captured an apparent expanding halo around the flaring neutron star SGR J1550-5418. The halo formed as X-rays from the brightest flares scattered off of intervening dust clouds. Credit: NASA/Swift/Jules Halpern, Columbia Univ. [more]

Scientists think the source of the flares is a spinning neutron star--the superdense, city-sized remains of a supernova. Although only about 12 miles across, a neutron star contains more mass than the sun. This particular neutron star is believed to be a "magnetar," a neutron star with an incredibly intense magnetic field.

A popular theory of soft-gamma-ray repeaters holds that flares are caused by "starquakes" in the outer rigid crust of the magnetar. As a magnetar´s colossal magnetic field shifts, it strains the crust with monstrous magnetic forces, often breaking it. When the crust snaps, it vibrates with seismic waves like in an earthquake and emits a flash of gamma-rays.



No one is really certain of the details, however, and much work remains to be done to understand these powerfully hyperactive stars.

NASA´s Fermi Gamma-ray Space Telescope, launched in June 2008, is ideal for this work. "The ability of Fermi´s gamma-ray burst monitor to resolve the fine structure within these events will help us better understand how magnetars unleash their energy," said Chryssa Kouveliotou, an astrophysicist at NASA´s Marshall Space Flight Center in Huntsville, Ala. The object has triggered Fermi´s gamma-ray burst monitor more than 95 times since Jan. 22nd.

NASA´s Wind satellite, the joint NASA-Japan Suzaku mission, and the European Space Agency´s INTEGRAL satellite also have detected flares from SGR J1550-5418.



[Edited by primus on 10-02-2009 at 21:50 GMT]

FEATURE

Green Comet Approaches Earth
02.04.2009


February 4, 2009: In 1996, a 7-year-old boy in China bent over the eyepiece of a small telescope and saw something that would change his life--a comet of flamboyant beauty, bright and puffy with an active tail. At first he thought he himself had discovered it, but no, he learned, two men named "Hale" and "Bopp" had beat him to it. Mastering his disappointment, young Quanzhi Ye resolved to find his own comet one day.

And one day, he did.

Fast forward to a summer afternoon in July 2007. Ye, now 19 years old and a student of meteorology at China´s Sun Yat-sen University, bent over his desk to stare at a black-and-white star field. The photo was taken nights before by Taiwanese astronomer Chi Sheng Lin on "sky patrol" at the Lulin Observatory. Ye´s finger moved from point to point--and stopped. One of the stars was not a star, it was a comet, and this time Ye saw it first.

Comet Lulin, named after the observatory in Taiwan where the discovery-photo was taken, is now approaching Earth. "It is a green beauty that could become visible to the naked eye any day now," says Ye.

Amateur astronomer Jack Newton sends this photo from his backyard observatory in Arizona:




"My retired eyes still cannot see the brightening comet," says Newton, "but my 14-inch telescope p****d it up quite nicely on Feb. 1st."

The comet makes its closest approach to Earth (0.41 AU) on Feb. 24, 2009. Current estimates peg the maximum brightness at 4th or 5th magnitude, which means dark country skies would be required to see it. No one can say for sure, however, because this appears to be Lulin´s first visit to the inner solar system and its first exposure to intense sunlight. Surprises are possible.


Sign up for EXPRESS SCIENCE NEWS delivery
Lulin´s green color comes from the gases that make up its Jupiter-sized atmosphere. Jets spewing from the comet´s nucleus contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2). Both substances glow green when illuminated by sunlight in the near-vacuum of space.

In 1910, many people panicked when astronomers revealed Earth would pass through the cyanogen-rich tail of Comet Halley. False alarm: The wispy tail of the comet couldn´t penetrate Earth´s dense atmosphere; even it if had penetrated, there wasn´t enough cyanogen to cause real trouble. Comet Lulin will cause even less trouble than Halley did. At closest approach in late February, Lulin will stop 38 million miles short of Earth, utterly harmless.

To see Comet Lulin with your own eyes, set your alarm for 3 am. The comet rises a few hours before the sun and may be found about 1/3rd of the way up the southern sky before dawn. Here are some dates when it is especially easy to find:

sky mapFeb. 6th: Comet Lulin glides by Zubenelgenubi, a double star at the fulcrum of Libra´s scales. Zubenelgenubi is not only fun to say (zuBEN-el-JA-newbee), but also a handy guide. You can see Zubenelgenubi with your unaided eye (it is about as bright as stars in the Big Dipper); binoculars pointed at the binary star reveal Comet Lulin in beautiful proximity. [sky map]




Feb. 16th: Comet Lulin passes Spica in the constellation Virgo. Spica is a star of first magnitude and a guidepost even city astronomers cannot miss. A finderscope pointed at Spica will capture Comet Lulin in the field of view, centering the optics within a nudge of both objects. [sky map]

Feb. 24th: Closest approach! On this special morning, Lulin will lie just a few degrees from Saturn in the constellation Leo. Saturn is obvious to the unaided eye, and Lulin could be as well. If this doesn´t draw you out of bed, nothing will. [sky map]

Ye notes that Comet Lulin is remarkable not only for its rare beauty, but also for its rare manner of discovery. "This is a ´comet of collaboration´ between Taiwanese and Chinese astronomers," he says. "The discovery could not have been made without a contribution from both sides of the Strait that separates our countries. Chi Sheng Lin and other members of the Lulin Observatory staff enabled me to get the images I wanted, while I analyzed the data and found the comet."

Somewhere this month, Ye imagines, another youngster will bend over an eyepiece, see Comet Lulin, and feel the same thrill he did gazing at Comet Hale-Bopp in 1996. And who knows where that might lead...?

"I hope that my experience might inspire other young people to pursue the same starry dreams as myself," says Ye.

FEATURE

NASA Sees the ´Dark Side´ of the Sun



January 23, 2009: Today, NASA researchers announced an event that will transform our view of the Sun and, in the process, super-charge the field of solar physics for many years to come.

"On February 6, 2011," says Chris St. Cyr of the Goddard Space Flight Center, "Super Bowl XLV will be played in Arlington, Texas."

Wait … that´s not it.

"And on the same day," he adds, "NASA´s two STEREO spacecraft will be 180 degrees apart and will image the entire Sun for the first time in history."

Right: An artist´s concept of one of the STEREO spacecraft. [Larger image]




STEREO´s deployment on opposite sides of the Sun solves a problem that has vexed astronomers for centuries: At any given moment they can see only half of the stellar surface. The Sun spins on its axis once every 25 days, so over the course of a month the whole Sun does turn to face Earth, but a month is not nearly fast enough to keep track of events. Sunspots can materialize, explode, and regroup in a matter of days; coronal holes open and close; magnetic filaments stretch tight and—snap!—they explode, hurling clouds of hot gas into the solar system. Fully half of this action is hidden from view, a fact which places space weather forecasters in an awkward position. How can you anticipate storms when you can´t see them coming? Likewise researchers cannot track the long-term evolution of sunspots or the dynamics of magnetic filaments because they keep ducking over the horizon at inconvenient times. STEREO´s global view will put an end to these difficulties.


The global view is still two years away. Already, however, the two spacecraft are beaming back over-the-horizon images that have researchers and forecasters glued to their monitors.

"This is a perspective we´ve never had before," says STEREO mission scientist Lika Guhathakurta of NASA headquarters. "We´re now monitoring more than 270 degrees of solar longitude—that´s 3/4ths of the star."

"After all these years," she laughs, "we´re finally getting to see the dark side of the Sun."

(Editor´s note: The Sun has no dark side. That was a solar physics joke.)

STEREO´s journey to the "dark side" began on Oct. 25, 2006, when the twin probes left Earth together onboard a Delta II rocket. High above the atmosphere, they separated and headed for the Moon. What happened next was a first in space navigation. The Moon acted as a gravitational slingshot, flinging the two probes in opposite directions—STEREO-A ahead of Earth and STEREO-B behind. They´ve been spreading apart ever since, and this is where they are now:



Above: The current positions of the STEREO Ahead (red) and Behind (green) spacecraft relative to the Sun (orange) and Earth (blue). The dotted lines show the angular displacement from the Earth. [more]

Because of the way the Sun spins (counterclockwise in the diagram above), STEREO-B gets a sneak preview of sunspots and coronal holes before they turn to face Earth—a boon for forecasters.

"I know forecasters at NOAA´s Space Weather Prediction Center monitor STEREO-B very closely," says St Cyr. "It lets them know what´s coming."

At the moment, STEREO-B enjoys a 3-day look-ahead advantage over Earth-based observatories. This has allowed researchers to predict geomagnetic storms as much as 72 hours earlier than ever before. On several occasions in late 2008, STEREO-B spotted a coronal hole spewing solar wind before any other spacecraft did. When the solar wind hit Earth, STEREO-B´s long-range forecast was validated by auroras like these:



Above: Photographer Brian Whittaker took this picture from the window of an airplane flying over Greenland on Nov. 9, 2008. The auroras were sparked by a solar wind impact anticipated by STEREO-B. Credit: Spaceweather.com.

St. Cyr notes that experienced ham radio operators can participate in this historic mission by helping NASA capture STEREO´s images. The busy Deep Space Network downloads data from STEREO only three hours a day. That´s plenty of time to capture all of the previous day´s data, but NASA would like to monitor the transmissions around the clock.

"So we´re putting together a ´mini-Deep Space Network´ to stay in constant contact with STEREO," says Bill Thompson, director of the STEREO Science Center at Goddard.

The two spacecraft beam their data back to Earth via an X-band radio beacon. Anyone with a 10-meter dish antenna and a suitable receiver can pick up the signals. The data rate is low, 500 bits per second, and it takes 3 to 5 minutes to download a complete image.

So far, the mini-Network includes stations in the United Kingdom, France and Japan—and Thompson is looking for more: "NASA encourages people with X-band antennas to contact the STEREO team. We would gladly work with them and figure out how they can join our network."

The two STEREO spacecraft rank among most sophisticated solar observatories launched by NASA to date. They are equipped with sensors that measure the speed, direction and composition of the solar wind; receivers that pick up radio emissions from explosions and shock waves in the sun´s atmosphere; telescopes that image the solar surface and all the tempests that rage there; and coronagraphs to monitor events in the sun´s outer atmosphere.

"So, really," says Guhathakurta, "we´re not only seeing the sun´s dark side, we´re feeling, tasting and listening to it as well."

[Edited by primus on 10-02-2009 at 21:57 GMT]

ABOUT THIS IMAGE:

In 1609, Galileo improved the newly invented telescope, turned it toward the heavens, and revolutionized our view of the universe. In celebration of the 400th anniversary of this milestone, 2009 has been designated as the International Year of Astronomy.

Today, NASA´s Great Observatories are continuing Galileo´s legacy with stunning images and breakthrough science from the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory.

While Galileo observed the sky using visible light seen by the human eye, technology now allows us to observe in many wavelengths, including Spitzer´s infrared view and Chandra´s view in X-rays. Each wavelength region shows different aspects of celestial objects and often reveals new objects that could not otherwise be studied.

This image of the spiral galaxy Messier 101 is a composite of views from Spitzer, Hubble, and Chandra.

• The red color shows Spitzer´s view in infrared light. It highlights the heat emitted by dust lanes in the galaxy where stars can form.

• The yellow color is Hubble´s view in visible light. Most of this light comes from stars, and they trace the same spiral structure as the dust lanes.

• The blue color shows Chandra´s view in X-ray light. Sources of X-rays include million-degree gas, exploded stars, and material colliding around black holes.

Such composite images allow astronomers to see how features seen in one wavelength match up with those seen in another wavelength. It´s like seeing with a camera, night vision goggles, and X-ray vision all at once.

In the four centuries since Galileo, astronomy has changed dramatically. Yet our curiosity and quest for knowledge remain the same. So, too, does our wonder at the splendor of the universe.

The International Year of Astronomy Great Observatories Image Unveiling is supported by the NASA Science Mission Directorate Astrophysics Division. The project is a collaboration between the Space Telescope Science Institute, the Spitzer Science Center, and the Chandra X-ray Center.

Object Names: M101, NGC 4547, The Pinwheel Galaxy

Image Type: Astronomical

ABOUT THIS IMAGE:

Detailed analysis of two continent-sized storms that erupted in Jupiter´s atmosphere in March 2007 shows that Jupiter´s internal heat plays a significant role in generating atmospheric disturbances. Understanding this outbreak could be the key to unlock the mysteries buried in the deep Jovian atmosphere, say astronomers.

Understanding these phenomena is important for Earth´s meteorology where storms are present everywhere and jet streams dominate the atmospheric circulation. Jupiter is a natural laboratory where atmospheric scientists study the nature and interplay of the intense jets and severe atmospheric phenomena.

An international team coordinated by Agustin Sánchez-Lavega from the Universidad del País Vasco in Spain presents its findings about this event in the January 24 issue of the journal Nature.

The team monitored the new eruption of cloud activity and its evolution with an unprecedented resolution using NASA´s Hubble Space Telescope, the NASA Infrared Telescope Facility in Hawaii, and telescopes in the Canary Islands (Spain). A network of smaller telescopes around the world also supported these observations.

According to the analysis, the bright plumes were storm systems triggered in Jupiter´s deep water clouds that moved upward in the atmosphere vigorously and injected a fresh mixture of ammonia ice and water about 20 miles (30 kilometers) above the visible clouds. The storms moved in the peak of a jet stream in Jupiter´s atmosphere at 375 miles per hour (600 kilometers per hour). Models of the disturbance indicate that the jet stream extends deep in the buried atmosphere of Jupiter, more than 60 miles (approximately100 kilometers) below the cloud tops where most sunlight is absorbed.

OTKRIVEN NAJBRŽI PLANET



Planet veličine Jupitera, koji se oko svog sunca okrene jednom dnevno, moglo bi dovesti u pitanje teoriju koliko planet uopće može biti blizu zvijede.

Novi planet, nazvan WASP-12b, je jedan i pol puta masivniji od Jupitera.
Nevjerojatno, ali istinito, treba mu tek malo više od jednog dana da se okrene oko svoje zvijezde, i to na orbiti koja iznosi tek jednu četrdesetinu udaljenosti od Zemlje do Sunca.
Čvrsti zagrljaj zagrijava WASP-12b na temperaturu od 2250 °Celzijevih – što je tek upola manje od površinske temperature Sunca i vruće kao neke druge zvijezde.
"Time je taj planet postao najvreliji do sada otkriven, a ujedno je i planet s najbržom orbitom", kaže Leslie Hebb s britanskog Sveučilišta St. Andrews.



Hebb i njezini kolege otkrili su diva u velikom istraživanju nazvanom Super Wide Angle Search for Planets (Superširoki kut potrage za planetima – SuperWASP).

U istraživanju se koriste dva niza teleskopa, jedan na španjolskim Kanarskim otocima, a drugi u Južnoj Africi, kako bi se tražili tragovi "tranzita" planeta, koji prolaze ispred svojih zvijezda i mijenjaju njihovu svjetlost, gledano sa Zemlje.


Ekstrasolarni planeti su preblijedi u usporedbi sa svojim zvijezdama da bi se mogla direktno mjeriti infracrvena svjetlost – ili vrućina – koju emitiraju.

No, astronomi mogu izračunati veličinu planeta i orbitalne udaljenosti iz promatranja tranzita.
Iz toga mogu izračunati koliko zvjezdane svjetlosti pada na njih pa prema tome i njihovu temperaturu.

Borba za najvreliji planet je vrlo neizvjesna. WASP-12b je s prvog mjesta upravo smijenio donedavnog rekordera, HD 149026b, čija se površina, crnja od najcrnjeg ugljena, zagrijava na ´samo´ 2040 °Celzija.

No, brza orbita WASP-12b mogla bi biti nedostižni rekord. Astronomi vjeruju da egzoplaneti veličine Jupitera nastaju podalje od svojih zvijezda, ali da vremenom migriraju u bližu orbitu.


To se događa zbog toga što u blizini zvijezde vjerojatno nije bilo dovoljno plina i prašine za nastanak takvih divovskih planeta.


"Većina egzoplaneta ima orbitalne periode od tri dana i duže", kaže Hebb, "što ukazuje da možda postoji neki mehanizam koji prijeći migraciju planeta još bliže njihovim zvijezdama".


"Kad planeti migriraju prema unutra zbog nečeg stanu i ostanu u periodu od tri dana", rekla je. "Iznenadila sam se što preiod može biti toliko kraći".


Veličina WASP-12b također može predstavljati izazov za objasniti. Njegov promjer je oko 1,8 puta veći od Jupiterovog, što je više nego se pretpostaljvalo da plinoviti divovi mogu narasti.


"Radijus planeta je sumnjivo velik", kaže Sara Seager s MIT-a. "Dok promatranja prate teoriju, neugodno je imati planet s polumjerom koji se ne uklapa u teoriju".


"Za sada nemamo nikakvo objašnjenje, ali bi zračenje sa zvijezde moglo ´napuhavati´ planet", kaže Hebb.


Sastav planeta, koji bi mogao biti bogat metalima, kao i njegova zvijezda, možda pojačava učinak.


Pretpostavlja se da su planeti bogati teškim metalima manje gusti od svojih ´slabometalnih´ rođaka.


Britanski tim sada će se posvetiti ultraljubičastom svjetlu koje isijava WASP-12b. Ta bi promatranja mogla otkriti što zvijezda čini njegovoj atmosferi.