Artist’s impression of the planet around Alpha Centauri B. Credit: ESO
Artist’s impression of the planet around Alpha Centauri B. Credit: ESO
Astronomers have discovered an enticing new planet that could be considered our next-door neighbor. The planet is orbiting a star in the Alpha Centauri system — the closest system to our own, just 4.3 light years away — and the planet has a mass about the same as Earth. It is also the lightest exoplanet ever discovered around a sun-like star. While this planet is likely too hot to contain life as we know it, the star system could possibly host other worlds that could be habitable, researchers from the European Southern Observatory at La Silla say.
“This result represents a major step towards the detection of Earth twins in the immediate vicinity of the Sun,” the team wrote in their paper.
“This is the first planet with a mass similar to Earth ever found around a star like the Sun. Its orbit is very close to its star and it must be much too hot for life as we know it,” said Stéphane Udry from the Geneva Observatory, a co-author of the paper that will be published in Nature on Oct. 17, and member of the team that used the HARPS instrument to find the planet. “But it may well be just one planet in a system of several. Our other HARPS results, and new findings from Kepler, both show clearly that the majority of low-mass planets are found in such systems.”
The planet is called Alpha Centauri Bb and it whips around its star every 3.2 days, orbiting at a distance of just 6 million kilometers (3.6 million miles), closer than Mercury’s orbit around the Sun. (Earth orbits at a comfortable 150 million kilometers (93 million miles) from the Sun.) So it is likely very hot and covered with molten rock, the researchers say.
Many astronomers have thought that the Alpha Centauri system would be a perfect candidate to host Earth-sized worlds. In fact, in 2008, a team of astronomers ran computer simulations of the system’s first 200 million years, and in each instance, despite different parameters, multiple terrestrial planets formed around the star. In every case, at least one planet turned up similar in size to the Earth, and in many cases this planet fell within the star’s habitable zone.
But while astronomers have looked for years, previous searches of planets in the Alpha Centauri system came up empty.
Until now.
“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” says Xavier Dumusque (Geneva Observatory, Switzerland and Centro de Astrofisica da Universidade do Porto, Portugal), lead author of the paper. “It’s an extraordinary discovery and it has pushed our technique to the limit!”
The European team detected the planet by using the radial velocity method — by picking up the tiny wobbles in the motion of the star Alpha Centauri B created by the gravitational pull of the orbiting planet. The effect is extremely small, as it causes the star to move back and forth by no more than 51 centimeters per second (1.8 km/hour). The team said this is the highest precision ever achieved using this method.
Alpha Centauri is one of the brightest stars in the southern skies and is actually a triple star — a system consisting of two stars similar to the Sun orbiting close to each other, designated Alpha Centauri A and B, and a more distant and faint red component known as Proxima Centauri.
Alpha Centauri B is very similar to the Sun but slightly smaller and less bright. The orbit of Alpha Centauri A is hundreds of times further away from the planet, but it would still be a very brilliant object in the planet’s skies.
A wide-field view of the sky around Alpha Centauri was created from photographic images forming part of the Digitized Sky Survey 2. The star appears so big just because of the scattering of light by the telescope’s optics as well as in the photographic emulsion. Credit: ESO
The first exoplanet around a Sun-like star was found by the same team back in 1995 and there are now 843 Exoplanets with the addition of Alpha Centauri Bb. Most are much bigger than Earth, and many are as big as Jupiter. The previous closest exoplanet was Epsilon Eridani b, 10.4 light years away.
The challenge astronomers now face is to detect and characterize a planet of mass comparable to the Earth that is orbiting in the habitable zone around another star. The first step has now been taken, the team says.
“This result represents a major step,” said Dumusque. “We live in exciting times!”
So, how long would it take for us to get to this planet? Using current technology, our slowest mode of space transportation, ion drive propulsion, it would take 81,000 years. Using the speeds of one of the fastest spacecraft (Helios 2) and traveling at a constant speed of 240,000 km/hr, it would take about 19,000 years (or over 600 generations) to travel the 4.3 light years.
Artist’s concept shows the New Horizons spacecraft during its 2015 encounter with Pluto and its moon, Charon. Credit: JHUAPL/SwRI
Since the New Horizons spacecraft left Earth back in 2006, there are a few things we know about the Pluto system now that we didn’t know then. For instance, it was discovered Pluto has two additional small moons – P4 and P5 — and Alan Stern, New Horizons Principal Investigator, said Pluto may have a large system of moons to be discovered as the spacecraft gets closer. There are also comets, possibly more dwarf planets and other objects out in the Kuiper Belt region where Pluto orbits.
“That’s exciting,” Stern said, “but this is a mixed story.”
Stern told Universe Today that while the spacecraft possibly could come upon an undiscovered moon or Kuiper Belt Object and they would have to alter course, the biggest issue is tiny debris which may be coming from impacts on the smaller moons.
“We could have 100 moons the size of P4 and they would not be a significant hazard,” Stern said via email. “The hazard is from ejecta coming off these satellites when they are cratered, because the ejecta escapes their feeble gravity and gets into orbit around Pluto.”
At a press conference at the American Astronomical Society’s Division for Planetary Sciences meeting, Stern said that with all the debris in the Kuiper Belt, objects are definitely getting impacted. “If hits occur on Pluto and Charon, they have enough gravity that ejecta just flies across the planet and creates secondary craters. But the ejecta on smaller moons puts shards and debris into the Pluto system.”
Stern said the ejecta speeds from these moons would be comparable to orbital speeds. That means the debris can orbit at any inclination, and there could be a cloud of debris around the system, creating a hazard for the spacecraft.
This worries Stern and his team.
“My spacecraft is going very fast and even a strike from something as small as a BB would be fatal,” he said. “There’s almost no place the spacecraft could get hit and it would be OK.”
Stern said current knowledge of the density of debris of the system can’t prove the spacecraft won’t get hit, and they won’t be able to find out more until they get closer.
“We’re going somewhere new and have no direct evidence of debris that could pose an impact hazard,” he said. “We don’t know what we are going to find and we might have to change our course.”
Stern and his team are looking at some alternative plans, and developing them now is crucial.
“When we plan an encounter for a mission like this, it literally takes tens of thousands of man-hours by experts to put that sequence together and test it,” he said. “We have to plan them now in order to complete that planning. We can’t complete them in the last couple of months or weeks.”
The plans being considered are called SHBOT: Safe Haven Bail Out Trajectory. They currently have nine different possible trajectories, depending on what they find as they get closer.
Screenshot from Stern’s presentation, depicting the nine SHBOT trajectories.
The team is also using every available tool — including sophisticated computer simulations of the stability of debris orbiting Pluto, giant ground-based telescopes, stellar occultation probes of the Pluto system, and even the Hubble Space Telescope — to search for debris in orbit.
Stern told Universe Today that they use the cameras on New Horizons itself every summer when they “wake up” the spacecraft. “LORRI (Long Range Reconnaissance Imager) has already seen Pluto for about 6 years!” he said, “But we won’t pass HST resolution till we’re about 10 weeks out, in April 2015. That’s when we turn on the heavy effort to look for more moons, rings, etc.”
They are looking at the pluses and minuses for each of the plans so they can be tested and be just as “bullet-proof” as the original, nominal flight plan.
In addition to saving the spacecraft, these alternative trajectories also need to preserve the science mission as much as possible. Most of the alternate courses bring the spacecraft farther away from the Pluto system, but one actually brings it closer to Charon, as the path there may be clearer there because of Charon’s gravity and clearing effect.
The spacecraft will start science observations in January 2015, with closest approach to the system currently set for on July 14, 2015 (“Bastille Day,” Stern said, “when we storm the gates of the Pluto system!”)
During the final 50 days of approach, when the spacecraft is taking pictures and sending them back to Earth to be analyzed, the team may discover something and have to fire the spacecraft engines, putting them on one of the SHBOT trajectories. But the last opportunity to actually change course is 10 days before encounter.
“After that we are in too close and we would run out of fuel and not complete the maneuver,” Stern said.
So, while the Mars Science Laboratory team had “Seven minutes of terror” during the perilous landing on Mars, Stern said they have something similar. “We don’t have seven minutes of terror; we have seven weeks of suspense.”
Cassiopeia A in Visible Light Courtesy of the Hubble Space Telescope
Greetings, fellow SkyWatchers! Whoops! (she blushes) I got so lost this weekend in researching Comet ISON that I almost forgot to post the forecast! Ah, well… As they say, better late than never, eh? If you do nothing else this week, be sure to catch the close apparition of Mercury and the “Earthshine Moon” on Wednesday and stay up late Saturday night to watch the Orionid Meteor Shower! In case I forget, just meet me in the back yard…
Monday, October 15 –Today in 1963 marks the first detection of an interstellar molecule. This discovery was made by Sander Weinreb (with Barrett, Meeks, and Henry) on the MIT Millstone Hill 84-foot dish. The discovery was made possible by new correlation receiver technology, and picked up a hydroxyl molecule in an absorption band. By using the radio galaxy Cas A as a background continuum source, the detection occurred at 1667.46 MHz and again at 1665.34 MHz. By the dawn of 2000, nearly 200 different interstellar molecules had been identified and many of these are classified as organic.
Tonight is New Moon! Let’s see what’s up there in the region of Cas A using visible light. The nearest bright star to Cas A is Beta Cassiopeiae – the bright star westward of the “W.” To locate the region of Cas A, go about three finger-widths due west of Beta and follow the subtle curve of three 5th magnitude stars. Cas A lies less than one degree south-southwest of the second star in the sequence of three. This star is a complex 5th magnitude multiple star system associated with variable star AR Cas.
Through binoculars, two stars of the AR system are easily resolved – the 4.9 magnitude primary is seen to be led across the sky by a 7.1 magnitude secondary (component C) which is a very tight double itself. Its 8.9 magnitude partner is resolvable in mid-sized scopes. Large aperture scopes may also be able to distinguish a 9.3 magnitude, second (B) component from the primary. Smaller scopes are back in the running again when attempting three 11th magnitude stars – none of which are close to the primary. Intermediate scopes can also hope to pick out a 12.9 magnitude H component northwest of C. 8.9 magnitude F also has a 9.1 magnitude near twin to the east-northeast. If you can see them all you should probably wrap an observatory building around your telescope – if one isn’t there already!
If you like to follow brightness changes in variables – AR Cas is not a good choice. This eclipsing type variable only fluctuates by a tenth of a magnitude over a period of 6 earth days.
Tuesday, October 16 – Let’s begin our evening by having a look at a radio source as we visit a pulsar located almost mid-way between Theta and Beta Capricorni – PSR2045+16.
While pulsars aren’t truly visible objects, there is still something undeniably cool about locating the field in which a rotating neutron star is sending out staccato pulses of radio waves anywhere between .001 and 4 seconds apart. If you have bright star 19 in the binocular field, then you know you’re in the right area for many radio sources, including many nearby quasars… Just imagine the possibilities!
Now let’s drop south-southeast of Beta Capricorni to have a look at a pair of doubles – Rho and Pi.
Northernmost Pi is a multiple system slightly less than 100 light-years away, with each discernable member also being a spectroscopic double. Separated by about an eighth of a light-year, look for a 5th magnitude yellow/white giant with a very close 9th magnitude companion. Further south is Pi, a triple star system which has a traditional name – Okul. Located around 670 light-years away, look for a bright blue/white 5th magnitude primary that is also a spectroscopic double – and its much easier C component, which is around magnitude 8.
Wednesday, October 17 – For naked-eye observers, enjoy the beautiful “Earthshine” Moon and the close apparition of Mercury!
While you’re out, be sure to gaze upon one of the finest of stars, Vega. Facing West at just after sundown, Vega is bright enough to shine even in the city and will appear just slightly below the zenith. The name Vega means “Falling Eagle” and it is the fifth brightest star in the sky. Enjoyed in either telescopes or binoculars, Vega has a wonderful bluish appearance and a lovely halo of spectra. This magnificent star holds a place in ancient legend and blossomed in our imaginations even more recently as it became the “star” of the movie “Contact”. As the western-most point of the “Southern Triangle”, Vega holds a special appeal for those born in the year 1985. Why? Because Vega is 27 light years away, the light you see from it tonight left the year you were born!
Now point those binoculars towards the northwestern corner of Capricornus and have a look a spectacular Alpha!
Although the Alpha 1 and 2 pairing is strictly a visual binary, that won’t stop you from enjoying their slightly yellow and orange colors. Collectively they are named Al Giedi, and the brighter of the pair is Alpha 2 at about 100 light-years distant; while Alpha 1 is around five times further away. Now power up with a telescope and you’ll find that both stars are also visual doubles! While the companion stars to both are around the same magnitude, you’ll find that Alpha 2 is separated by three times as much distance. Be sure to mark your observation lists and enjoy!
Thursday, October 18 – Today in 1959, Soviet Luna 3 began returning the first photographs of the Moon’s far side. Also today – but in 1967 – the Soviets again made history as Venera 4 became the first spacecraft to probe Venus’ atmosphere.
Have you checked out Mars lately? Mars is now leaving the constellation Scorpius and entering Ophiuchus. At more than 2 AU away from Earth, Mars has become quite dim, and its minimal apparent visual brightness is +1.24 magnitude. Can you still spot a few of its more prominent features?
For a true telescope challenge, we’ll have to go out on a limb – the southeastern lunar limb – to have a look at an unusual crater. Named for the French agrochemist and botanist Jean-Baptiste Boussingault, this elliptical-appearing crater actually spans a handsome 71 kilometers. What makes Boussingault so unusual is that it is home to its own large interior crater – A. This double-ring formation gives it a unique stepped, concentric look that’s worth your time!
When we’re done? Let’s go have a look at Gamma Aquilae just for the heck of it. Just northwest of bright Altair, Gamma has the very cool name of Tarazed and is believed to be over 300 light-years away. This K3 type giant will show just a slightly yellow coloration – but what really makes this one special is the low power field!
Friday, October 19 – Our lunar mission for tonight is a revisit on a crater named for historian and theologian Denis Pétau – Petavius! Located almost centrally along the terminator in the southeast quadrant, a lot will depend tonight on your viewing time and the age the Moon itself. Perhaps when you look, you’ll see 177 kilometer diameter Petavius cut in half by the terminator. If so, this is a great time to take a high magnification look at the small range of mountain peaks contained in its center, as well as a deep rima which runs for 80 kilometers across its otherwise fairly smooth surface. To the east lies a long furrow in the landscape. This deep runnel is Palitzsch and its Valles. While the primary crater which forms this deep gash is only 41 kilometers wide, the valley itself stretches for 110 kilometers. Look for crater Haas on Petavius’ southern edge with Snellius to the southwest and Wrottesley along its northwest wall.
Now, let’s go have a look at the northeastern corner of Capricornus as we learn about Delta…
Its proper name is Deneb Algedi and this nearly 3rd magnitude star is a stunning blue/ white. Curiously enough, it’s a rather close star – only about 50 light-years from Earth. Hovering so close to it that we cannot even correctly assess its spectral type is a binary companion whose eclipsing orbit causes Delta to be a very slight variable – with a period of just about one day. In its own way, Delta is rather historic… For it was only 4 degrees north of this star that Uranus was first sighted by Galle in 1846!
Saturday, October 20 – Tonight, let’s check out a lunar map and go hunting! First let’s start with a look at the Mare Fecunditatus region: (1)Taruntius, (2) Secchi, (3) Messier and Messier A, (4) Lubbock, (5) Guttenberg, (6) Montes Pyrenees, (7) Goclenius, (8) Magelhaens, (9) Columbo, (10) Webb, (11) Langrenus, (12) Lohse, (13) Lame, (14) Vendelinus, (15) the Luna 16 landing site
Mare Fecunditatus Region Photographic Map – Image Credit – Greg Konkel
And here is a closer look at the area around Atlas and Hercules: (1) Mare Humboldtianum, (2) Endymion, (3) Atlas, (4) Hercules, (5) Chevalier, (6) Shuckburgh, (7) Hooke, (8) Cepheus, (9) Franklin, (10) Berzelius, (11) Maury, (12) Lacus Somniorum, (13) Daniel, (14) Grove, (15) Williams, (16) Mason, (17) Plana, (18) Burg, (19) Lacus Mortis, (20) Baily, (21) Atlas E, (22) Keldysh, (23) Mare Frigoris, (24) Democritus, (25) Gartner, (26) Schwabe, (27) Thales, (28) Strabo, (29) de la Rue, (30) Hayn.
Atlas and Hercules Region Photographic Map – Image Credit – Greg Konkel
Have fun marking off lunar challenge craters from your list!
After having looked at the Moon, take the time out to view a bright southern star – Fomalhaut (RA 22 57 39 Dec -29 37 20). Also known as “The Lonely One,” Alpha Piscis Austrini seems to sit in a rather empty area in the southern skies, some 23 light-years away. At magnitude 1, this main sequence A3 giant is the southernmost visible star of its type for northern hemisphere viewers, and is the 18th brightest star in the sky. The Lonely One is about twice the diameter of our own Sun, but 14 times more luminous! Just a little visual aid is all that it takes to reveal its optical companion…
Now we are slipping into the stream of Comet Halley and into one of the finest meteor showers of the year. If skies are clear tonight, this would be the perfect chance to begin your observations of the Orionid meteor shower. But, wait for the Moon to set!
Sunday, October 21 – Be sure to be outdoors before dawn to enjoy one of the year’s most reliable meteor showers. The offspring of Comet Halley will grace the early morning hours as they return once again as the Orionid meteor shower. This dependable shower produces an average of 10-20 meteors per hour at maximum and the best activity begins before local midnight on the 20th, and reaches its best as Orion stands high to the south at about two hours before local dawn on the 21st. With the Moon nearly out of the morning picture, this is gonna’ be great!
Although Comet Halley has long since departed our Solar System, the debris left from its trail still remain scattered in Earth’s orbital path around the Sun, allowing us to predict when this meteor shower will occur. We first enter the “stream” at the beginning of October and do not leave it until the beginning of November, making your chances of “catching a falling star” even greater! These meteors are very fast, and although they are faint, it is still possible to see an occasional fireball that leaves a persistent trail.
For best success, try to get away from city lights. Facing south-southeast, simply relax and enjoy the stars of the winter Milky Way. The radiant, or apparent point of origin, for this shower will be near the red giant Alpha Orionis (Betelguese), but meteors may occur from any point in the sky. You will make your meteor watching experience much more comfortable if you take along a lawn chair, a blanket and a thermos of your favorite beverage.
Clouded out? Don’t despair. You don’t always need your eyes or perfect weather to meteor watch. By tuning an FM radio to the lowest frequency possible that does not receive a clear signal, you can practice radio meteor listening! An outdoor FM antenna pointed at the zenith and connected to your receiver will increase your chances, but it’s not necessary. Simply turn up the static and listen. Those hums, whistles, beeps, bongs, and occasional snatches of signals are our own radio signals being reflected off the meteor’s ion trail! Pretty cool, huh?
Hubble’s view of massive galaxy cluster MACS J0717.5+3745. The large field of view is a combination of 18 separate Hubble images. Credit:
NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM)
Earlier this year, astronomers using the Hubble Space Telescope were able to identify a slim filament of dark matter that appeared to be binding a pair of distant galaxies together. Now, another filament has been found, and scientists a have been able to produce a 3-D view of the filament, the first time ever that the difficult-to-detect dark matter has been able to be measured in such detail. Their results suggest the filament has a high mass and, the researchers say, that if these measurements are representative of the rest of the Universe, then these structures may contain more than half of all the mass in the Universe.
Dark matter is thought to have been part of the Universe from the very beginning, a leftover from the Big Bang that created the backbone for the large-scale structure of the Universe.
“Filaments of the cosmic web are hugely extended and very diffuse, which makes them extremely difficult to detect, let alone study in 3D,” said Mathilde Jauzac, from Laboratoire d’Astrophysique de Marseille in France and University of KwaZulu-Natal, in South Africa, lead author of the study.
The team combined high resolution images of the region around the massive galaxy cluster MACS J0717.5+3745 (or MACS J0717 for short) – one of the most massive galaxy clusters known — and found the filament extends about 60 million light-years out from the cluster.
The team said their observations provide the first direct glimpse of the shape of the scaffolding that gives the Universe its structure. They used Hubble, NAOJ’s Subaru Telescope and the Canada-France-Hawaii Telescope, with spectroscopic data on the galaxies within it from the WM Keck Observatory and the Gemini Observatory. Analyzing these observations together gives a complete view of the shape of the filament as it extends out from the galaxy cluster almost along our line of sight.
The team detailed their “recipe” for studying the vast but diffuse filament. .
First ingredient: A promising target. Theories of cosmic evolution suggest that galaxy clusters form where filaments of the cosmic web meet, with the filaments slowly funnelling matter into the clusters. “From our earlier work on MACS J0717, we knew that this cluster is actively growing, and thus a prime target for a detailed study of the cosmic web,” explains co-author Harald Ebeling (University of Hawaii at Manoa, USA), who led the team that discovered MACS J0717 almost a decade ago.
Second ingredient: Advanced gravitational lensing techniques. Albert Einstein’s famous theory of general relativity says that the path of light is bent when it passes through or near objects with a large mass. Filaments of the cosmic web are largely made up of dark matter [2] which cannot be seen directly, but their mass is enough to bend the light and distort the images of galaxies in the background, in a process called gravitational lensing. The team has developed new tools to convert the image distortions into a mass map.
Third ingredient: High resolution images. Gravitational lensing is a subtle phenomenon, and studying it needs detailed images. Hubble observations let the team study the precise deformation in the shapes of numerous lensed galaxies. This in turn reveals where the hidden dark matter filament is located. “The challenge,” explains co-author Jean-Paul Kneib (LAM, France), “was to find a model of the cluster’s shape which fitted all the lensing features that we observed.”
Finally: Measurements of distances and motions. Hubble’s observations of the cluster give the best two-dimensional map yet of a filament, but to see its shape in 3D required additional observations. Colour images [3], as well as galaxy velocities measured with spectrometers [4], using data from the Subaru, CFHT, WM Keck, and Gemini North telescopes (all on Mauna Kea, Hawaii), allowed the team to locate thousands of galaxies within the filament and to detect the motions of many of them.
A model that combined positional and velocity information for all these galaxies was constructed and this then revealed the 3D shape and orientation of the filamentary structure. As a result, the team was able to measure the true properties of this elusive filamentary structure without the uncertainties and biases that come from projecting the structure onto two dimensions, as is common in such analyses.
The results obtained push the limits of predictions made by theoretical work and numerical simulations of the cosmic web. With a length of at least 60 million light-years, the MACS J0717 filament is extreme even on astronomical scales. And if its mass content as measured by the team can be taken to be representative of filaments near giant clusters, then these diffuse links between the nodes of the cosmic web may contain even more mass (in the form of dark matter) than theorists predicted.
The International Space Station appears to go to warp speed — a la Star Trek, Star Wars and almost every other space flick — in this new video created by Christoph Malin, who “stacked” image sequences that the ISS crew at International Space Station have been taking lately. These are the images that have been used to create the great timelapse videos, that provide a sense of what it is like to fly over the Earth on the space station. But this one is different, and as Malin says, “Stacks make interesting patterns visible, for example lightning corridors within clouds. One can also sometimes recognize satellite tracks and meteors – patterns that are not amongst the main star trails.”
The Cassini spacecraft takes an angled view toward Saturn, showing the southern reaches of the planet with the rings on a dramatic diagonal. Credit: NASA/JPL-Caltech/Space Science Institute
The Cassini mission has been a source of awe-inspiring images, surprising science and incredible longevity. Since launching on Oct. 15, 1997, the Cassini spacecraft has logged more than 6.1 billion kilometers (3.8 billion miles)of exploration – enough to circle Earth more than 152,000 times. After flying by Venus twice, Earth, and then Jupiter on its way to Saturn, Cassini pulled into orbit around the ringed planet in 2004 and has been spending its last eight years weaving around Saturn, its glittering rings and intriguing moons.
The spacecraft has sent back some 444 gigabytes of scientific data so far, including more than 300,000 images. More than 2,500 reports have been published in scientific journals based on Cassini data, describing the discovery of the plume of water ice and organic particles spewing from the moon Enceladus; the first views of the hydrocarbon-filled lakes of Saturn’s largest moon Titan; the atmospheric upheaval from a rare, monstrous storm on Saturn and many other curious phenomena.
The folks from the Cassini mission have put together a great infographic that provides a timeline of Cassini’s mission and some of its “greatest hits” — major events and discoveries. See below:
This week’s Carnival of Space is hosted by Brie Allen at the Tranquility Base blog. This is Brie’s first time hosting, so you should definitely check out this “small website exploring a big universe!”
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
Artist concept of a previous multi-planet solar system found by the Kepler spacecraft. Credit: NASA/Tim Pyle
Most planetary systems found by astronomers so far are quite different than our own. Many have giant planets whizzing around in a compact configuration, very close to their star. An extreme case in point is a newly found solar system that was announced on October 15, 2012 which packs five — count ‘em — five planets into a region less than one-twelve the size of Earth’s orbit!
“This is an extreme example of a compact solar system,” said researcher Darin Ragozzine from the University of Florida, speaking at a press conference at the American Astronomical Society’s Division for Planetary Sciences meeting. “If we can understand this one, hopefully we can understand how these types of systems form and why most known planetary systems appear different from our own solar system.”
This new system, currently named KOI-500, was found with data from the Kepler planet-finding spacecraft, and Ragozzine said astronomers have now uncovered a new realm of exo-planetary systems.
“The real exciting thing is that Kepler has found hundreds of stars with multiple transiting planets,” he said. “These are the most information-rich systems, as they can tell you not only about the planets, but also the architecture of how solar systems are put together.”
The fact that almost all solar systems found so far are vastly different than our own has astronomers wondering if we are, in fact, the oddballs. A study from 2010 concluded that only about 10 – 15 percent of stars in the Universe host systems of planets like our own, with terrestrial planets nearer the star and several gas giant planets in the outer part of the solar system.
Part of the reason our dataset of exoplanets is skewed with planets that are close to the star is because currently, that is all we are capable of detecting.
But the surprising new population of planetary systems discovered in the Kepler data that contain several planets packed in a tiny space around their host stars does give credence to the thinking that our solar system may be somewhat unique.
However, perhaps KOI-500 used to be more like our solar system.
“From the architecture of this planetary system, we infer that these planets did not form at their current locations,” Ragozzine said. “The planets were originally more spread out and have ‘migrated’ into the ultra-compact configuration we see today.”
There are several theories about the formation of the large planets in our outer solar system which involves the planets moving and migrating inward and outward during the formation process. But why didn’t the inner planets, including Earth, move in closer, too?
“We don’t know why this didn’t happen in our solar system,” Ragozzine said, but added that KOI-500 will “become a touchstone for future theories that will attempt to describe how compact planetary systems form. Learning about these systems will inspire a new generation of theories to explain why our solar system turned out so differently.”
A few notes of interest about KOI-500:
The five planets have “years” that are only 1.0, 3.1, 4.6, 7.1, and 9.5 days.
“All five planets zip around their star within a region 150 times smaller in area than the Earth’s orbit, despite containing more material than several Earths (the planets range from 1.3 to 2.6 times the size of the Earth). At this rate, you could easily pack in 10 more planets, and they would still all fit comfortably inside the Earth’s orbit,” Ragozzine noted. KOI-500 is approximately 1,100 light-years away in the constellation Lyra, the harp.
Four of the planets orbiting KOI-500 follow synchronized orbits around their host star in a completely unique way — no other known system contains a similar configuration. Work by Ragozzine and his colleagues suggests that planetary migration helped to synchronize the planets.
“KOI” stands for Kepler Object of Interest, and Ragozzine’s findings on this system have not yet been published, and so the system has yet to officially be considered a confirmed planetary system. “Every time we find something like this we give it a license-plate-like number starting with KOI,” Ragozzine said.
When does a KOI become an official planet? Ragozzine said the process is by confirming and validating the data. “Basically you need to prove statistically or by getting a specific measurement that it is not some other astronomical signal,” he said.
This infographic from Space.com supplies more visual details:
Felix Baumgartner salutes his suit-mounted camera before stepping off his capsule’s platform at 128,000 feet (Red Bull Stratos)
Yesterday, October 14, Austrian pilot and BASE jumper Felix Baumgartner became the first person to skydive from over 128,000 feet, breaking the sound barrier during his 4 minute, 20 second plummet from the “edge of space.” A new video from Red Bull Stratos includes views from Felix’s suit-mounted cameras as he drops through virtually no atmosphere, smoothly at first but then going into a wild spin… but eventually stabilizing himself for the remainder of his fall and opening his chute at just over 6,000 feet. Incredible!
Check out the video below:
Here’s how Baumgartner described the spin and how he got out of it during the press conference after his jump yesterday:
“It started out really good because my exit was perfect, I did exactly what I was supposed to do… It looked like for a second I was going to tumble two more times and then get it under control, but for some reason that spin became so violent over all axis and it was hard to know how to get out of it, because, if you are trapped in a pressurized suit – normally as a skydiver you can feel the air and get direct feedback from the air — but here you are trapped in a suit that is pressurized at 3.5 PSI so you don’t know how to feel the air. It is like swimming without touching the water. And it’s hard because every when time it turns you around you have to figure out what to do. So I was sticking my arm out and it became worse and then I stuck arm out the other side and it became less, so I was fighting all the way down to regain control because I wanted to break the speed of sound. And I hit it. I don’t know how many seconds, but I could feel air was building up and then I hit it.”
So, in that quote, Baumgartner seemed to describe that he could feel when he broke the speed of sound, but in answering the next question of how it felt, he kind of backtracked and said he didn’t feel it.
“It’s hard to describe because I didn’t feel it. When you are in the pressure suit, you don’t feel anything, it is like being in a cast…. We have to look at the data – at what point did it happen — was I still spinning or was I under control? If you want to chart speed you need a reference point of things that pass you by, or sound, or your suit if flapping. I didn’t have that.”
Read more about Baumgartner’s record (and sound!) -breaking achievement and see lots more images and video here.
ADDED: A version of the video showing his chute opening (and with some background music added) can be found here on iloveskydiving.org.
A family portrait of the PH1 planetary system that was discovered in part due to crowdsourcing. Image Credit: Haven Giguere/Yale.
A family portrait of the PH1 planetary system: The newly discovered planet is depicted in this artist’s rendition transiting the larger of the two eclipsing stars it orbits. Off in the distance, well beyond the planet orbit, resides a second pair of stars bound to the planetary system. Image Credit: Haven Giguere/Yale.
A planet has been discovered orbiting in a four-star system — and no, that doesn’t mean the accommodations and conditions are excellent. It literally means four stars, where a planet is orbiting a binary star system that in turn is orbited by a second distant pair of stars. This is the first system like this that has ever been found, and its discovery demonstrates the power of citizen scientists, as it was found by a joint effort of amateurs participating on the Planet Hunters website under the guidance of professional astronomers.
This is might be an extremely rare planetary setup, astronomer Meg Schwamb from Yale says, as only six planets are currently known to orbit two stars, and none of these are orbited by other stellar companions. Astronomers are calling the newly found world a ‘circumbinary’ planet.
“Circumbinary planets are the extremes of planet formation,” said Schwamb, Planet Hunters scientist and lead author of a paper about the system presented Oct. 15 at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Reno, Nevada. “The discovery of these systems is forcing us to go back to the drawing board to understand how such planets can assemble and evolve in these dynamically challenging environments.”
The planet is called PH1, for the first confirmed planet identified by the Planet Hunters citizen scientists, but it has the nickname of Tatooine, the planet in Star Wars that orbited two suns.
Planet Hunters uses data from the Kepler spacecraft, specially designed for looking for signs of planets.
The volunteers, Kian Jek of San Francisco and Robert Gagliano of Cottonwood, Arizona, spotted faint dips in light caused by the planet as it passed in front of its parent stars, a common method of finding extrasolar planets. Schwamb, a Yale postdoctoral researcher, led the team of professional astronomers that confirmed the discovery and characterized the planet, following observations from the Keck telescopes on Mauna Kea, Hawaii. PH1 is a gas giant with a radius about 6.2 times that of Earth, making it a bit bigger than Neptune.
“Planet Hunters is a symbiotic project, pairing the discovery power of the people with follow-up by a team of astronomers,” said Debra Fischer, a professor of astronomy at Yale and planet expert who helped launch Planet Hunters in 2010. “This unique system might have been entirely missed if not for the sharp eyes of the public.”
PH1 orbits outside the 20-day orbit of a pair of eclipsing stars that are 1.5 and 0.41 times the mass of the Sun. This planet is dense — it has perhaps about 170 times more mass than Earth — and is about half the diameter of Jupiter. It revolves around its host stars roughly every 138 days. Beyond the planet’s orbit at about 1000 AU (roughly 1000 times the distance between Earth and the Sun) is a second pair of stars orbiting the planetary system.
Gagliano, one of the two citizen scientists involved in the discovery, said he was “absolutely ecstatic to spot a small dip in the eclipsing binary star’s light curve from the Kepler telescope, the signature of a potential new circumbinary planet, ‘Tatooine,’ and it’s a great honor to be a Planet Hunter, citizen scientist, and work hand in hand with professional astronomers, making a real contribution to science.”
Jek expressed wonder at the possibility of the discovery: “It still continues to astonish me how we can detect, let alone glean so much information, about another planet thousands of light years away just by studying the light from its parent star.”
