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Posts Tagged ‘solar systems’

Astronomers Identify The Closest Known Flyby Of A Star To Our Solar System: A Dim Star That Passed Through The Oort Cloud 70,000 Years Ago

February 18, 2015 Leave a comment

Credit: Michael Osadciw/University of Rochester.

Credit: Michael Osadciw/University of Rochester.

A group of astronomers from the US, Europe, Chile and South Africa have determined that 70,000 years ago a recently discovered dim star is likely to have passed through the solar system’s distant cloud of comets, the Oort Cloud. No other star is known to have ever approached our solar system this close – five times closer than the current closest star, Proxima Centauri.

In a paper published in Astrophysical Journal Letters, lead author Eric Mamajek from the University of Rochester and his collaborators analyzed the velocity and trajectory of a low-mass star system nicknamed “Scholz’s star.”

The star’s trajectory suggests that 70,000 years ago it passed roughly 52,000 astronomical units away (or about 0.8 light years, which equals 8 trillion kilometers, or 5 trillion miles). This is astronomically close; our closest neighbor star Proxima Centauri is 4.2 light years distant. In fact, the astronomers explain in the paper that they are 98% certain that it went through what is known as the “outer Oort Cloud” – a region at the edge of the solar system filled with trillions of comets a mile or more across that are thought to give rise to long-period comets orbiting the Sun after their orbits are perturbed.

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Vesta’s Rocky History


© NASA/JPL - Caltech / UCLA / MPS / DLR / IDA

© NASA/JPL – Caltech / UCLA / MPS / DLR / IDA

Rocks are silent storytellers: because each mineral is created only under certain conditions, they provide insight into the evolution of the body on which they are found. Scientists from the Max Planck Institute for Solar System Research (MPS) in Germany have now begun to tell such a story from the enigmatic dark material discovered on the protoplanet Vesta. Using data from the framing camera aboard NASA’s Dawn spacecraft, the researchers have succeeded for the first time in identifying a mineral component of this material: serpentine. The new discovery puts an end to the discussion about the origin of the dark material: impacts of primitive asteroids must have distributed it on Vesta.

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NASA’s WISE Survey Finds Thousands Of New Stars, But No ‘Planet X’

March 8, 2014 1 comment

Image credit: DSS/NASA/JPL-Caltech

Image credit: DSS/NASA/JPL-Caltech

After searching hundreds of millions of objects across our sky, NASA’s Wide-Field Infrared Survey Explorer (WISE) has turned up no evidence of the hypothesized celestial body in our solar system commonly dubbed “Planet X.”

Researchers previously had theorized about the existence of this large, but unseen celestial body, suspected to lie somewhere beyond the orbit of Pluto. In addition to “Planet X,” the body had garnered other nicknames, including “Nemesis” and “Tyche.”

This recent study, which involved an examination of WISE data covering the entire sky in infrared light, found no object the size of Saturn or larger exists out to a distance of 10,000 astronomical units (au), and no object larger than Jupiter exists out to 26,000 au. One astronomical unit equals 93 million miles. Earth is 1 au, and Pluto about 40 au, from the sun.

“The outer solar system probably does not contain a large gas giant planet, or a small, companion star,” said Kevin Luhman of the Center for Exoplanets and Habitable Worlds at Penn State University, University Park, Pa., author of a paper in the Astrophysical Journal describing the results.

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Archival Hubble Images Reveal Neptune’s “Lost” Inner Moon

October 9, 2013 1 comment

Neptune’s tiny, innermost moon, Naiad, has now been seen for the first time since it was discovered by Voyager’s cameras in 1989. Dr. Mark Showalter, a senior research scientist at the SETI Institute in Mountain View, California, announced the result today in Denver, Colorado, at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society. He and collaborators Dr. Jack Lissauer of the NASA Ames Research Center, Dr. Imke de Pater of UC Berkeley, and Robert French of the SETI Institute, also released a dramatic new image of Neptune’s puzzling rings and ring-arcs, which were first imaged by Voyager.

“Naiad has been an elusive target ever since Voyager left the Neptune system,” said Dr. Showalter. From Earth, Neptune is 2 million times brighter than Naiad, and the two are separated by only one arcsecond. “This is equivalent to the width of a human hair from 50 feet away,” noted collaborator Lissauer. The team of astronomers needed to develop new techniques to suppress Neptune’s glare. Naiad was finally revealed, moving across a sequence of eight images taken during December 2004.

Strangely, Naiad appears to have veered significantly off course. The astronomers are puzzled by the fact that Naiad is now far ahead of its predicted orbital position. They wonder whether gravitational interactions with one of Neptune’s other moons may have caused it to speed up, although the details remain mysterious. Further observations will be needed in order to understand Naiad’s motion.

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Upgrade To Mars Rovers Could Aid Discovery On More Distant Worlds

September 10, 2013 1 comment

Smart as the Mars Curiosity mission has been about landing and finding its own way on a distant world, the rover is pretty brainless when it comes to doing the science that it was sent 567 million kilometers to carry out. That has to change if future rover missions are to make discoveries further out in the solar system, scientists say.

The change has now begun with the development of a new camera that can do more than just take pictures of alien rocks – it also thinks about what the pictures signify so the rover can decide on its own whether to keep exploring a particular site, or move on.

“We currently have a micromanaging approach to space exploration,” said senior researcher Kiri Wagstaff, a computer scientist and geologist at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “While this suffices for our rovers on Mars, it works less and less well the further you get from the Earth. If you want to get ambitious and go to Europa and asteroids and comets, you need more and more autonomy to even make that feasible.”

Full Story: http://www.agu.org/news/press/pr_archives/2013/2013-43.shtml

IBEX Spacecraft Measures Changes In The Direction Of Interstellar Winds Buffeting Our Solar System

September 6, 2013 Leave a comment

Data from NASA’s Interstellar Boundary Explorer (IBEX) spacecraft reveal that neutral interstellar atoms are flowing into the solar system from a different direction than previously observed.

Interstellar atoms flow past the Earth as the solar system passes through the surrounding interstellar cloud at 23 kilometers per second (50,000 miles per hour). The latest IBEX measurements of the interstellar wind direction were discovered to differ from those made by the Ulysses spacecraft in the 1990s. That difference led the IBEX team to compare the IBEX measurements to data gathered by 11 spacecraft between 1972 and 2011. Statistical testing of the Earth-orbiting and interplanetary spacecraft data showed that, over the past 40 years, the longitude of the interstellar helium wind has changed by 6.8 ± 2.4 degrees.

“We concluded it’s highly likely that the direction of the interstellar wind has changed over the past 40 years. It’s also highly unlikely that the direction of the interstellar helium wind has remained constant,” says Dr. Priscilla Frisch, lead author of the study and a senior scientist in the Department of Astronomy and Astrophysics at the University of Chicago.

Full Story: http://www.swri.org/9what/releases/2013/ibex-wind.htm#.UilbyiywUV0

A Cometary Graveyard


A team of astronomers from the University of Anitoquia, Medellin, Colombia, have discovered a graveyard of comets. The researchers, led by Antioquia astronomer Prof. Ignacio Ferrin, describe how some of these objects, inactive for millions of years, have returned to life leading them to name the group the ‘Lazarus comets’. The team publish their results in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.

The new work looked at a third and distinct region of the Solar System, the main belt of asteroids between the orbits of Mars and Jupiter. This volume of space contains more than 1 million objects ranging in size from 1 m to 800 km. The traditional explanation for asteroids is that they are the building blocks of a planet that never formed, as the movement of the pieces was disrupted by the strong gravitational field of Jupiter.

In the last decade 12 active comets have been discovered in the asteroid main belt region. This was something of a surprise and the Medellin team set out to investigate their origin. The team, made up of Prof. Ferrin and his colleagues Profs. Jorge Zuluaga and Pablo Cuartas, now think they have an explanation.

“We found a graveyard of comets”, exclaims Professor Ferrín. He adds: “Imagine all these asteroids going around the Sun for aeons, with no hint of activity. We have found that some of these are not dead rocks after all, but are dormant comets that may yet come back to life if the energy that they receive from the Sun increases by a few per cent.”

Full Story: http://www.ras.org.uk/news-and-press/224-news-2013/2325-a-cometary-graveyard