Double-Star Systems Can Be Dangerous for Exoplanets | Space.com
Alien planets born in widely separated two-star systems face a grave danger of being booted into interstellar space, a new study suggests.
Exoplanets circling a star with a far-flung stellar companion — worlds that are part of “wide binary” systems — are susceptible to violent and dramatic orbital disruptions, including outright ejection, the study found.
Such effects are generally limited to sprawling planetary systems with at least one distantly orbiting world, while more compact systems are relatively immune. This finding, which observational evidence supports, should help astronomers better understand the structure and evolution of alien solar systems across the galaxy, researchers said.
Located in a relatively vacant region of space about 4200 light-years away and difficult to see using an amateur telescope, the lonesome planetary nebula NGC 7354 is often overlooked.
However, thanks to this image captured by the NASA/ESA Hubble Space Telescope we are able to see this brilliant ball of smoky light in spectacular detail.
Just as shooting stars are not actually stars and lava lamps do not actually contain lava, planetary nebulae have nothing to do with planets. The name was coined by Sir William Herschel because when he first viewed a planetary nebula through a telescope, he could only identify a hazy smoky sphere, similar to gaseous planets such as Uranus.
The name has stuck even though modern telescopes make it obvious that these objects are not planets at all, but the glowing gassy outer layers thrown off by a hot dying star.
It is believed that winds from the central star play an important role in determining the shape and morphology of planetary nebulae. The structure of NGC 7354 is relatively easy to distinguish. It consists of a circular outer shell, an elliptical inner shell, a collection of bright knots roughly concentrated in the middle and two symmetrical jets shooting out from either side. Research suggests that these features could be due to a companion central star, however the presence of a second star in NGC 7354 is yet to be confirmed.
A new galaxy class has been identified using observations from ESO’s Very Large Telescope (VLT), the Gemini South telescope, and the Canada-France-Hawaii Telescope (CFHT). Nicknamed “green bean galaxies” because of their unusual appearance, these galaxies glow in the intense light emitted from the surroundings of monster black holes and are amongst the rarest objects in the Universe.
Many galaxies have a giant black hole at their centre that causes the gas around it to glow. However, in the case of green bean galaxies, the entire galaxy is glowing, not just the centre. These new observations reveal the largest and brightest glowing regions ever found, thought to be powered by central black holes that were formerly very active but are now switching off.
Astronomer Mischa Schirmer of the Gemini Observatory had looked at many images of the distant Universe, searching for clusters of galaxies, but when he came across one object in an image from the Canada-France-Hawaii Telescope he was stunned — it looked like a galaxy, but it was bright green. It was unlike any galaxy he had ever seen before, something totally unexpected. He quickly applied to use ESO’s Very Large Telescope to find out what was creating the unusual green glow.
“ESO granted me special observing time at very short notice and just a few days after I submitted my proposal, this bizarre object was observed using the VLT,” says Schirmer. “Ten minutes after the data were taken in Chile, I had them on my computer in Germany. I soon refocused my research activities entirely as it became apparent that I had come across something really new.”
The new object has been labelled J224024.1−092748 or J2240. It lies in the constellation of Aquarius (The Water Bearer) and its light has taken about 3.7 billion years to reach Earth.
After the discovery, Schirmer’s team searched through a list of nearly a billion other galaxies and found 16 more with similar properties, which were confirmed by observations made at the Gemini South telescope. These galaxies are so rare that there is on average only one in a cube about 1.3 billion light-years across. This new class of galaxies has been nicknamed green bean galaxies because of their colour and because they are superficially similar to, but larger than, green pea galaxies.
In many galaxies the material around the supermassive black hole at the centre gives off intense radiation and ionises the surrounding gas so that it glows strongly. These glowing regions in typical active galaxies are usually small, up to 10% of the diameter of the galaxy. However, the team’s observations showed that in the case of J2240, and other green beans spotted since, it is truly huge, spanning the entire object. J2240 displays one of the biggest and brightest such regions ever found. Ionised oxygen glows bright green, which explains the strange colour that originally caught Schirmer’s attention.
“These glowing regions are fantastic probes to try to understand the physics of galaxies — it’s like sticking a medical thermometer into a galaxy far, far away,” says Schirmer. “Usually, these regions are neither very large nor very bright, and can only be seen well in nearby galaxies. However, in these newly discovered galaxies they are so huge and bright that they can be observed in great detail, despite their large distances.” — Astronomer Mischa Schirmer of the Gemini Observatory
Astronomers have discovered what may be the most massive black hole ever known in a small galaxy about 250 million light-years from Earth, scientists say.
Image: This image shows the disk galaxy NGC 1277, as seen by the Hubble Space Telescope. The small, flattened galaxy has one of the biggest central super-massive black holes ever found in its center, the equivalent of 17 billion suns.<.em> Credit: NASA / ESA / Andrew C. Fabian / Remco C. E. van den Bosch (MPIA)
The supermassive black hole has a mass equivalent to 17 billion suns and is located inside the galaxy NGC 1277 in the constellation Perseus. It makes up about 14 percent of its host galaxy’s mass, compared with the 0.1 percent a normal black hole would represent, scientists said.
“This is a really oddball galaxy,” said study team member Karl Gebhardt of the University of Texas at Austin in a statement. “It’s almost all black hole. This could be the first object in a new class of galaxy-black hole systems.”
The giant black hole is about 11 times as wide as the orbit of Neptune around our sun, researchers said. The mass is so far above normal that the scientists took a year to double-check and submit their research paper for publication, according to the study’s lead author, Remco van den Bosch.
“The first time I calculated it, I thought I must have done something wrong. We tried it again with the same instrument, then a different instrument,” van den Bosch, an astronomer at Germany’s Max Planck Institute for Astronomy, told SPACE.com. “Then I thought, ‘Maybe something else is happening.’”
Amazing new photos from NASA’s Cassini probe orbiting Saturn reveal a dizzying glimpse into a monster storm raging on the ringed planet’s north pole.
Image: NASA / JPL-Caltech / SSI
Cassini took the spectacular Saturn storm photos Tuesday and relayed it back to Earth the same day, mission scientists said in a statement. The pictures reveal a swirling storm reminiscent of the recent Hurricane Sandy that recently plagued our own planet.
Saturn’s mysterious northern vortex, a vast hexagon-shaped storm, dominates this photo taken Tuesday by NASA’s Cassini spacecraft.
The tempest is located in a strange hexagonal cloud vortex at Saturn’s north pole that was first discovered by the Voyager spacecraft in the early 1980s, and sighted more closely by Cassini since then. The strange six-sided feature is thought to be formed by the path of a jet stream flowing through the planet’s atmosphere.
“Cassini’s recent excursion into inclined orbits has given mission scientists a vertigo-inducing view of Saturn ‘s polar regions, and what to our wondering eyes has just appeared: roiling storm clouds and a swirling vortex at the center of Saturn’s famed northern polar hexagon,” Cassini scientists wrote in an online update.
Astronomers have spotted seven galaxies that existed just a few hundred million years after the universe’s birth, including one that may be the oldest found to date.
This new image of the Hubble Ultra Deep Field (HUDF) 2012 campaign reveals a previously unseen population of seven faraway galaxies, which are observed as they appeared in a period 350 million to 600 million years after the big bang. Credit: NASA, ESA, R. Ellis (Caltech), and the UDF 2012 Team
The potential record-holding galaxy, known as UDFj-39546284, likely existed when the universe was just 380 million years old, researchers said, and may be the farthest galaxy ever seen. The other six distant galaxies all formed within 600 million years of the Big Bang, which created our universe 13.7 billion years ago.
UDFj-39546284 was detected previously, and researchers had thought it formed just 500 million years or so after the Big Bang. The new observations, made using NASA’s Hubble Space Telescope, push its probable formation time back even further.
The seven galaxies constitute the first reliable census of the epoch from 400 million to 600 million years after the universe’s birth, researchers said. This census detects a steady increase in galaxies over this period, suggesting that the formation of the first stars and galaxies — the so-called “cosmic dawn” — happened gradually rather than suddenly.
“The cosmic dawn was probably not a single, dramatic event,” study lead author Richard Ellis, of Caltech in Pasadena, told reporters today (Dec. 12).
Ellis and his team pointed Hubble at a small patch of sky known as the Hubble Ultra Deep Field, which the telescope observed for many hours to build up enough light to spot extremely faint, distant objects. The researchers used Hubble’s Wide Field Camera 3 to study the deep field in near-infrared wavelengths during August and September 2012.
The astronomers used special filters to measure the galaxies’ redshifts — how much their light has been stretched by the expansion of space. From the redshifts, the researchers were able to calculate the distance to each galaxy, revealing their ages.
The results “represent our cosmic roots,” said Harvard astronomer Abraham Loeb, who was not involved in the study. The new Hubble data “comes from the biggest archaeological dig that we have of the universe.”
Light from some of the universe’s most energetic explosions is allowing scientists to probe the nature of space-time, according to new observations of so-called gamma-ray bursts from the Japanese Aerospace Exploration Agency’s Ikaros spacecraft. Photons released by these bursts help place limits on a unified model of all of the forces of nature — what scientists call a “theory of everything.”
Using the Gamma-Ray Burst Polarimeter (GAP) onboard the spacecraft, a team of Japanese scientists have made the most precise measurements of energetic gamma-ray burst photons to date.
“This result puts a fundamental constraint on quantum gravity, a dream theory reconciling Einstein’s theory of relativity and quantum theory,” Kenji Toma, of Osaka University, said in a statement.
The false colors in this image indicate altitude.
Credit: Erich Karkoschka (University of Arizona) and NASA
The green and blue regions show where the atmosphere is clear, allowing sunlight to penetrate deep into Uranus. In the yellow and gray regions, a haze or cloud layer is reflecting sunlight away. Orange and red colors indicate very high clouds, like cirrus clouds on Earth.
NASA scientists took time on Wednesday (Nov. 28) to soothe 2012 doomsday fears, warning against the dark side of Mayan apocalypse rumors — frightened children and suicidal teens who truly fear the world may come to an end Dec. 21.
Image: Artist’s conception of the rogue planet Nibiru, or Planet X. Credit: gilderm | sxc.hu
These fears are based on misinterpretations of the Mayan calendar. On the 21st, the date of the winter solstice, a calendar cycle called the 13th b’ak’tun comes to an end. Although Maya scholars agree that the ancient Maya would not have seen this day as apocalyptic, rumors have spread that a cosmic event may end life on Earth on that day.
Thus NASA’s involvement. The space agency maintains a 2012 information page debunking popular Mayan apocalypse rumors, such as the idea that a rogue planet will hit Earth on Dec. 21, killing everyone. (In fact, astronomers are quite good at detecting near-Earth objects, and any wandering planet scheduled to collide with Earth in three weeks would be the brightest object in the sky behind the sun and moon by now.)
“There is no true issue here,” David Morrison, an astrobiologist at NASA Ames Research Center, said during a NASA Google+ Hangout event today (Nov. 28). “This is just a manufactured fantasy.”
Unfortunately, Morrison said, the fantasy has real-life consequences. As one of NASA’s prominent speakers on 2012 doomsday myths, Morrison said, he receives many emails and letters from worried citizens, particularly young people. Some say they can’t eat, or are too worried to sleep, Morrison said. Others say they’re suicidal.
“While this is a joke to some people and a mystery to others, there is a core of people who are truly concerned,” he said.
Not every 2012 apocalypse believer thinks the world will end on Dec. 21. Some, inspired by New Age philosophies, expect a day of universal peace and spiritual transformation. But it’s impressionable kids who have NASA officials worried.
“I think it’s evil for people to propagate rumors on the Internet to frighten children,” Morrison said.
Myths and misconceptions
NASA scientists took questions via social media in the hour-long video chat, debunking doomsday myths from the rogue planet Nibiru to the danger of killer solar flares.
In fact, said NASA heliophysicist Lika Guhathakurta, it’s true that the sun is currently in an active phase of its cycle, meaning electromagnetic energy has picked up. Large solar flares can impact electronics and navigation systems on Earth, but satellites monitoring the sun give plenty of warning and allow officials to compensate for the extra electromagnetic activity when it hits our atmosphere. What’s more, Guhathakurta said, this particular solar maximum is the “wimpiest” in some time — scientists have no reason to expect solar storms beyond what our planet has weathered in the past.
Nor are any near-Earth objects, planetary or otherwise, threatening to slam into our planet on Dec. 21, said Don Yeomans, a planetary scientist who tracks near-Earth objects at NASA’s Jet Propulsion Laboratory. The only close asteroid approach on the horizon is forecast to occur on Feb. 13, 2013, when an asteroid will pass within 4.5 Earth radii to our planet (for perspective, Earth’s radius is 3,963 miles, or 6,378 kilometers). The asteroid is not going to hit Earth, Yeomans said.
Other rumors — that the Earth’s magnetic field will suddenly reverse or that the planet will travel almost 30,000 light-years and fall into the black hole at the center of the Milky Way galaxy — were also dismissed. (A light-year is the distance light travels in one year, or about 6 trillion miles, or 10 trillion km.)
One popular rumor that the planet will undergo a complete blackout from Dec. 23 to 25 earned a “What?” and blank looks from the panel of scientists.
Ultimately, concerns about Earth’s fate would be better focused on slow-acting problems such as climate change rather than some sort of cosmic catastrophe, said Andrew Fraknoi, an astronomer at Foothill College in California.
Mitzi Adams, a heliophysicist at NASA’s Marshall Space Flight Center, agreed.
“The greatest threat to Earth in 2012, at the end of this year and in the future, is just from the human race itself,” Adams said.
The Most Ancient Spiral Galaxy Discovered?
Around 10.7 billion years old is the record now held by this beautiful spiral galaxy, BX442. Discovered using NASA’s Hubble Space Telescope, this discovery puts the researchers at odds with current wisdom. Prior theories stated that such spiral galaxies wouldn’t have formed at such an early stage of the universe, but this discovery seems to contradict this.
Image credit: Dunlap Institute for Astronomy & Astrophysics/Jo Bergeron