A couple of recent TMRO.tv SpacePod short video reports:
* Europa Ho! – SpacePod 10/16/15
TMRO Chief Astronomer Jared Head takes a look at the recently approved Europa Multiple Flyby Mission.
* The Water of Mars – SpacePod 10/9/15
TMRO Chief Astronomer Jared Head looks at the latest results suggesting liquid water is present on the surface of Mars.
TMRO Space Pods are crowd funded shows. If you like this episode consider contributing to help us to continue to improve. Head over tohttp://www.patreon.com/spacepod for information, goals and reward levels. Don’t forget to check out our weekly live show campaign as well over at http://www.patreon.com/tmro
Using ESO’s Very Large Telescope, an international team of astronomers have found the hottest and most massive double star with components so close that they touch each other. The two stars in the extreme system VFTS 352 could be heading for a dramatic end, during which the two stars either coalesce to create a single giant star, or form a binary black hole.
The double star system VFTS 352 is located about 160 000 light-years away in the Tarantula Nebula[1]. This remarkable region is the most active nursery of new stars in the nearby Universe and new observations from ESO’s VLT [2] have revealed that this pair of young stars is among the most extreme and strangest yet found.
VFTS 352 is composed of two very hot, bright and massive stars that orbit each other in little more than a day. The centres of the stars are separated by just 12 million kilometres [3]. In fact, the stars are so close that their surfaces overlap and a bridge has formed between them. VFTS 352 is not only the most massive known in this tiny class of “overcontact binaries” — it has a combined mass of about 57 times that of the Sun — but it also contains the hottest components — with surface temperatures above 40 000 degrees Celsius.
Extreme stars like the two components of VFTS 352, play a key role in the evolution of galaxies and are thought to be the main producers of elements such as oxygen. Such double stars are also linked to exotic behaviour such as that shown by “vampire stars”, where a smaller companion star sucks matter from the surface of its larger neighbour (eso1230).
This animated artist’s impression shows VFTS 352 — the hottest and most massive double star system to date where the two components are in contact and sharing material. The two stars in this extreme system lie about 160 000 light-years from Earth in the Large Magellanic Cloud. This intriguing pair could be heading for a dramatic end, either with the creation of a single monster star or the formation of a binary black hole. Credit: ESO/L. Calçada
In the case of VFTS 352, however, both stars in the system are of almost identical size. Material is, therefore, not sucked from one to another, but instead may be shared [4]. The component stars of VFTS 352 are estimated to be sharing about 30 per cent of their material.
Such a system is very rare because this phase in the life of the stars is short, making it difficult to catch them in the act. Because the stars are so close together, astronomers think that strong tidal forces lead to enhanced mixing of the material in the stellar interiors.
This zoom sequence starts with a broad panorama of the southern night sky and closes in on the Tarantula star-forming region in the Large Magellanic Cloud. Among the many hot young stars here lies VFTS 352 — the hottest and most massive double star system to date where the two components are in contact and sharing material. The final frames show a close-up of the region of this exotic object, in an image created from images from the Wide Field Imager at the MPG/ESO 2.2-metre telescope at La Silla. Credit: Credit: ESO/N. Risinger (skysurvey.org)/R. Gendler Music Johan B Monell
“The VFTS 352 is the best case yet found for a hot and massive double star that may show this kind of internal mixing,” explains lead author Leonardo A. Almeida of the University of São Paulo, Brazil. “As such it’s a fascinating and important discovery.”
Astronomers predict that VFTS 352 will face a cataclysmic fate in one of two ways. The first potential outcome is the merging of the two stars, which would likely produce a rapidly rotating, and possibly magnetic, gigantic single star. “If it keeps spinning rapidly it might end its life in one of the most energetic explosions in the Universe, known as a long-duration gamma-ray burst,” says the lead scientist of the project, Hugues Sana, of the University of Leuven in Belgium [5].
The second possibility is explained by the lead theoretical astrophysicist in the team, Selma de Mink of University of Amsterdam: “If the stars are mixed well enough, they both remain compact and the VFTS 352 system may avoid merging. This would lead the objects down a new evolutionary path that is completely different from classic stellar evolution predictions. In the case of VFTS 352, the components would likely end their lives in supernova explosions, forming a close binary system of black holes. Such a remarkable object would be an intense source of gravitational waves.”
Proving the existence of this second evolutionary path [6] would be an observational breakthrough in the field of stellar astrophysics. But, regardless of how VFTS 352 meets its demise, this system has already provided astronomers with valuable new insights into the poorly understood evolutionary processes of massive overcontact binary star systems.
Notes
[1] This star’s name indicates that it was observed as part of the VLT FLAMES Tarantula Survey, which utilised the FLAMES and GIRAFFE instruments on ESO’s Very Large Telescope (VLT) to study over 900 stars in the 30 Doradus region of theLarge Magellanic Cloud (LMC). The survey has already led to many exciting and important findings including the fastest rotating star (eso1147), and an extremely massive solitary runaway star (eso1117). It is helping to answer many fundamental questions concerning how massive stars are affected by rotation, binarity and the dynamics in dense star clusters.
[2] This study also used brightness measurements of VFTS 352 over a period of twelve years made as part of the OGLE survey.
[3] Both components are classed as O-type stars. Such stars are typically between 15 and 80 times more massive than the Sun and can be up to a million times brighter. They are so hot that they shine with a brilliant blue-white light and have surface temperatures over 30 000 degrees Celsius.
[4] These regions around the stars are known as Roche lobes. In an overcontact binary such as VFTS 352 both stars overfill their Roche lobes.
[5] Gamma-ray Bursts (GRBs) are bursts of highly energetic gamma rays that are detected by orbiting satellites. They come in two types — short duration (shorter than a few seconds), and long duration (longer than a few seconds). Long-duration GRBs are more common and are thought to mark the deaths of massive stars and be associated with a class of very energetic supernova explosions.
[6] Predicted by Einstein’s theory of general relativity, gravitational waves are ripples in the fabric of space and time. Significant gravitational waves are generated whenever there are extreme variations of strong gravitational fields with time, such as during the merger of two black holes.
Little is known about Magic Leap’s device, but [company President and CEO Rony Abovitz] described it as a small, self-contained computer that people will feel comfortable using in public. It is believed to involve retinal projection, and evolved out of surgical research. (Abovitz’s previous business involved medical devices.) And when it arrives, Magic Leap will likely compete with Microsoft’s HoloLens, which is now taking applications for its development kits.
* This video was released today:
Shot directly through Magic Leap technology on 10/14/15, without the use of special effects or compositing.
NASA’s Cassini spacecraft has begun returning its best-ever views of the northern extremes of Saturn’s icy, ocean-bearing moon Enceladus. The spacecraft obtained the images during its Oct. 14 flyby, passing 1,142 miles (1,839 kilometers) above the moon’s surface. Mission controllers say the spacecraft will continue transmitting images and other data from the encounter for the next several days.
Scientists expected the north polar region of Enceladus to be heavily cratered, based on low-resolution images from the Voyager mission, but the new high-resolution Cassini images show a landscape of stark contrasts. “The northern regions are crisscrossed by a spidery network of gossamer-thin cracks that slice through the craters,” said Paul Helfenstein, a member of the Cassini imaging team at Cornell University, Ithaca, New York. “These thin cracks are ubiquitous on Enceladus, and now we see that they extend across the northern terrains as well.”
In addition to the processed images, unprocessed, or “raw,” images are posted on the Cassini mission website at:
Cassini’s next encounter with Enceladus is planned for Oct. 28, when the spacecraft will come within 30 miles (49 kilometers) of the moon’s south polar region. During the encounter, Cassini will make its deepest-ever dive through the moon’s plume of icy spray, sampling the chemistry of the extraterrestrial ocean beneath the ice. Mission scientists are hopeful data from that flyby will provide evidence of how much hydrothermal activity is occurring in the moon’s ocean, along with more detailed insights about the ocean’s chemistry — both of which relate to the potential habitability of Enceladus.
Cassini’s final close Enceladus flyby will take place on Dec. 19, when the spacecraft will measure the amount of heat coming from the moon’s interior. The flyby will be at an altitude of 3,106 miles (4,999 kilometers).
An online toolkit for all three final Enceladus flybys is available at:
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency’s Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.
NASA launched a new website Monday so the world can see images of the full, sunlit side of the Earth every day. The images are taken by a NASA camera one million miles away on the Deep Space Climate Observatory (DSCOVR), a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force.
Once a day NASA will post at least a dozen new color images of Earth acquired from 12 to 36 hours earlier by NASA’s Earth Polychromatic Imaging Camera (EPIC). Each daily sequence of images will show the Earth as it rotates, thus revealing the whole globe over the course of a day. The new website also features an archive of EPIC images searchable by date and continent.
The primary objective of NOAA’s DSCOVR mission is to maintain the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA. NASA has two Earth-observing instruments on the spacecraft. EPIC’s images of Earth allow scientists to study daily variations over the entire globe in such features as vegetation, ozone, aerosols, and cloud height and reflectivity.
EPIC is a four megapixel CCD camera and telescope. The color Earth images are created by combining three separate single-color images to create a photographic-quality image equivalent to a 12-megapixel camera. The camera takes a series of 10 images using different narrowband filters — from ultraviolet to near infrared — to produce a variety of science products. The red, green and blue channel images are used to create the color images. Each image is about 3 megabytes in size.
“The effective resolution of the DSCOVR EPIC camera is somewhere between 6.2 and 9.4 miles (10 and 15 kilometers),” said Adam Szabo, DSCOVR project scientist at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.
Since Earth is extremely bright in the darkness of space, EPIC has to take very short exposure images (20-100 milliseconds). The much fainter stars are not visible in the background as a result of the short exposure times.
The DSCOVR spacecraft orbits around the L1 Lagrange point directly between Earth and the sun. This orbit keeps the spacecraft near the L1 point and requires only occasional small maneuvers, but its orbit can vary from 4 to 15 degrees away from the sun-Earth line over several years.
EPIC was built by Lockheed Martin’s Advanced Technology Center, in Palo Alto, California. Using an 11.8-inch (30-centimeter) telescope and 2048 x 2048 CCD detector, EPIC measures in the ultraviolet, visible and near-infrared areas of the spectrum. The data from all 10 wavelengths are posted through a website hosted by the Atmospheric Science Data Center at NASA’s Langley Research Center, Hampton, Virginia. All images are in the public domain.
NASA uses the vantage point of space to increase our understanding of our home planet, improve lives, and safeguard our future. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.