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Sharp-Eyed Alma Spots A Flare On Famous Red Giant Star
Artist’s impression of a giant flare on the surface of red giant Mira A. Credit: Katja Lindblom, CC BY-NC-ND 4.0
Super-sharp observations with the telescope Alma have revealed what seems to be a gigantic flare on the surface of Mira, one of the closest and most famous red giant stars in the sky. Activity like this in red giants – similar to what we see in the Sun – comes as a surprise to astronomers. The discovery could help explain how winds from giant stars make their contribution to our galaxy’s ecosystem.
New observations with Alma have given astronomers their sharpest ever view of the famous double star Mira. The images clearly show the two stars in the system, Mira A and Mira B, but that’s not all. For the first time ever at millimetre wavelengths, they reveal details on the surface of Mira A.
“Alma’s vision is so sharp that we can begin to see details on the surface of the star. Part of the stellar surface is not just extremely bright, it also varies in brightness. This must be a giant flare, and we think it’s related to a flare which X-ray telescopes observed some years ago”, says Wouter Vlemmings, astronomer at Chalmers, who led the team.
Circular Orbits Identified For Small Exoplanets
Artist’s conception. Image courtesy of NASA
Viewed from above, our solar system’s planetary orbits around the sun resemble rings around a bulls-eye. Each planet, including Earth, keeps to a roughly circular path, always maintaining the same distance from the sun.
For decades, astronomers have wondered whether the solar system’s circular orbits might be a rarity in our universe. Now a new analysis suggests that such orbital regularity is instead the norm, at least for systems with planets as small as Earth.
In a paper published in the Astrophysical Journal, researchers from MIT and Aarhus University in Denmark report that 74 exoplanets, located hundreds of light-years away, orbit their respective stars in circular patterns, much like the planets of our solar system.
These 74 exoplanets, which orbit 28 stars, are about the size of Earth, and their circular trajectories stand in stark contrast to those of more massive exoplanets, some of which come extremely close to their stars before hurtling far out in highly eccentric, elongated orbits.
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Cassini Sends Final Close Views Of Odd Moon Hyperion
Image credit: NASA/JPL-Caltech/Space Science Institute
NASA’s Cassini spacecraft has returned images from its final close approach to Saturn’s oddball moon Hyperion, upholding the moon’s reputation as one of the most bizarre objects in the solar system. The views show Hyperion’s deeply impact-scarred surface, with many craters displaying dark material on their floors.
During this flyby, Cassini passed Hyperion at a distance of about 21,000 miles (34,000 kilometers) at closest approach. Cassini’s closest-ever Hyperion flyby took place on Sept. 26, 2005, at a distance of 314 miles (505 kilometers).
Hyperion is the largest of Saturn’s irregular, or potato-shaped, moons and may be the remnant of a violent collision that shattered a larger object into pieces. Cassini scientists attribute Hyperion’s peculiar, sponge-like appearance to the fact that it has an unusually low density for such a large object — about half that of water. Its low density indicates Hyperion is quite porous, with weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.
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NASA Instrument On Rosetta Makes Comet Atmosphere Discovery
Image credit: ESA/Rosetta/NAVCAM
Data collected by NASA’s Alice instrument aboard the European Space Agency’s Rosetta spacecraft reveal that electrons close to the surface of comet 67P/Churyumov-Gerasimenko — not photons from the sun, as had been believed — cause the rapid breakup of water and carbon dioxide molecules spewing from the comet’s surface.
“The discovery we’re reporting is quite unexpected,” said Alan Stern, principal investigator for the Alice instrument at the Southwest Research Institute (SwRI) in Boulder, Colorado. “It shows us the value of going to comets to observe them up close, since this discovery simply could not have been made from Earth or Earth orbit with any existing or planned observatory. And, it is fundamentally transforming our knowledge of comets.
A report of the findings has been accepted for publication by the journal Astronomy and Astrophysics.
NASA’s Europa Mission Begins With Selection Of Science Instruments
Bizarre features on Europa’s icy surface. Credits: NASA/JPL-Caltech
NASA has selected nine science instruments for a mission to Jupiter’s moon Europa, to investigate whether the mysterious icy moon could harbor conditions suitable for life.
NASA’s Galileo mission yielded strong evidence that Europa, about the size of Earth’s moon, has an ocean beneath a frozen crust of unknown thickness. If proven to exist, this global ocean could have more than twice as much water as Earth. With abundant salt water, a rocky sea floor, and the energy and chemistry provided by tidal heating, Europa could be the best place in the solar system to look for present day life beyond our home planet.
“Europa has tantalized us with its enigmatic icy surface and evidence of a vast ocean, following the amazing data from 11 flybys of the Galileo spacecraft over a decade ago and recent Hubble observations suggesting plumes of water shooting out from the moon,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “We’re excited about the potential of this new mission and these instruments to unravel the mysteries of Europa in our quest to find evidence of life beyond Earth.”
Hubble Observes One-of-a-Kind Star Nicknamed ‘Nasty’
Artist’s Illustration Credit: NASA, ESA, and G. Bacon (STScI)
Astronomers using NASA’s Hubble Space Telescope have uncovered surprising new clues about a hefty, rapidly aging star whose behavior has never been seen before in our Milky Way galaxy. In fact, the star is so weird that astronomers have nicknamed it “Nasty 1,” a play on its catalog name of NaSt1. The star may represent a brief transitory stage in the evolution of extremely massive stars.
First discovered several decades ago, Nasty 1 was identified as a Wolf-Rayet star, a rapidly evolving star that is much more massive than our sun. The star loses its hydrogen-filled outer layers quickly, exposing its super-hot and extremely bright helium-burning core.
But Nasty 1 doesn’t look like a typical Wolf-Rayet star. The astronomers using Hubble had expected to see twin lobes of gas flowing from opposite sides of the star, perhaps similar to those emanating from the massive star Eta Carinae, which is a Wolf-Rayet candidate. Instead, Hubble revealed a pancake-shaped disk of gas encircling the star. The vast disk is nearly 2 trillion miles wide, and may have formed from an unseen companion star that snacked on the outer envelope of the newly formed Wolf-Rayet. Based on current estimates, the nebula surrounding the stars is just a few thousand years old, and as close as 3,000 light-years from Earth.
NASA’s WISE Spacecraft Discovers Most Luminous Galaxy In Universe
Artist’s concept. Image credit: N/A
A remote galaxy shining with the light of more than 300 trillion suns has been discovered using data from NASA’s Wide-field Infrared Survey Explorer (WISE). The galaxy is the most luminous galaxy found to date and belongs to a new class of objects recently discovered by WISE — extremely luminous infrared galaxies, or ELIRGs.
“We are looking at a very intense phase of galaxy evolution,” said Chao-Wei Tsai of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, lead author of a new report appearing in the May 22 issue of The Astrophysical Journal. “This dazzling light may be from the main growth spurt of the galaxy’s black hole.
The brilliant galaxy, known as WISE J224607.57-052635.0, may have a behemoth black hole at its belly, gorging itself on gas. Supermassive black holes draw gas and matter into a disk around them, heating the disk to roaring temperatures of millions of degrees and blasting out high-energy, visible, ultraviolet, and X-ray light. The light is blocked by surrounding cocoons of dust. As the dust heats up, it radiates infrared light.
Galaxy’s Snacking Habits Revealed
Images Credit: Angel Lopez-Sanchez (AAO/MQU) and Baerbel Koribalski (CSIRO)
A team of Australian and Spanish astronomers have caught a greedy galaxy gobbling on its neighbours and leaving crumbs of evidence about its dietary past.
Galaxies grow by churning loose gas from their surroundings into new stars, or by swallowing neighbouring galaxies whole. However, they normally leave very few traces of their cannibalistic habits.
A study published today in Monthly Notices of the Royal Astronomical Society (MNRAS) not only reveals a spiral galaxy devouring a nearby compact dwarf galaxy, but shows evidence of its past galactic snacks in unprecedented detail.
Australian Astronomical Observatory (AAO) and Macquarie University astrophysicist, Ángel R. López-Sánchez, and his collaborators have been studying the galaxy NGC 1512 to see if its chemical story matches its physical appearance.
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Giant Spiraling Molecular Gas Arms As Cradles Of Dense Massive Molecular Cores
Credit: ALMA(ESO/NAOJ/NRAO), H. B. Liu, J. Dale
A research team led by Dr. Hauyu Liu at the Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA) observed the luminous OB cluster-forming massive molecular clump G33.92+0.11 with the Atacama Large Millimeter/submillimeter Array (ALMA), and unveiled the fine molecular gas structures deeply embedded at the center of the parent molecular cloud. This finding provides a greatly simplified picture of overall cloud geometry and kinematics, which represents a crucial step forward in the understanding of the upper end of the stellar and molecular core mass functions. The research was published in the April 28 issue of The Astrophysical Journal.
Via ALMA observations, this research for the first time resolved an embedded giant coherent dense gas structure on a several light-year scale. Surprisingly, this dense gas structure presents several spiral arms, which appear like a version of the previously observed spiral arms surrounding the low-mass protobinary, scaled-up by a factor of ~103. These giant spiral arms, and the massive molecular gas cores located at their convergence, are cradles to form the highest mass stars in this stellar cluster.
Supernova Hits Star, Results Shocking
Photo Credit: Courtesy of Dan Kasen
The origin of type Ia supernovae, the standard candles used to reveal the presence of dark energy in the universe, is one of astronomy’s most beguiling mysteries. Astronomers know they occur when a white dwarf explodes in a binary system with another star, but the properties of that second star — and how it triggers the explosion — have remained elusive for decades.
Now, a team of astronomers from the intermediate Palomar Transient Factory (iPTF), including those associated with UC Santa Barbara, have witnessed a supernova smashing into a nearby star, shocking it, and creating an ultraviolet glow that reveals the size of the companion. The discovery involved the rapid response and coordination of iPTF, NASA’s Swift satellite and the new capabilities of the Las Cumbres Observatory Global Telescope Network (LCOGT).
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