NASA’S HUBBLE FINDS SUPERNOVA STAR SYSTEM LINKED TO POTENTIAL ‘ZOMBIE STAR’
From the FMS Global News Desk of Jeanne Hambleton Released: 6-Aug-2014 -Space Telescope Science Institute Citations Nature, August-2014
Using NASA’s Hubble Space Telescope, a team of astronomers has spotted a star system that could have left behind a “zombie star” after an unusually weak supernova explosion.
A supernova typically obliterates the exploding white dwarf, or dying star. On this occasion, scientists believe this faint supernova may have left behind a surviving portion of the dwarf star — a sort of zombie star.
While examining Hubble images taken years before the stellar explosion, astronomers identified a blue companion star feeding energy to a white dwarf, a process that ignited a nuclear reaction and released this weak supernova blast.
This supernova, Type Iax, is less common than its brighter cousin, Type Ia. Astronomers have identified more than 30 of these mini-supernovas that may leave behind a surviving white dwarf.
“Astronomers have been searching for decades for the star systems that produce Type Ia supernova explosions,” said scientist Saurabh Jha of Rutgers University in Piscataway, New Jersey.
“Type Ia’s are important because they’re used to measure vast cosmic distances and the expansion of the universe. But we have very few constraints on how any white dwarf explodes. The similarities between Type Iax’s and normal Type Ia’s make understanding Type Iax progenitors important, especially because no Type Ia progenitor has been conclusively identified. This discovery shows us one way that you can get a white dwarf explosion.”
The team’s results will appear in the Thursday, Aug. 7 edition of the journal Nature.
The weak supernova, dubbed SN 2012Z, resides in the host galaxy NGC 1309 which is 110 million light-years away.
It was discovered in the Lick Observatory Supernova Search in January 2012. Luckily, Hubble’s Advanced Camera for Surveys also observed NGC 1309 for several years prior the supernova outburst, which allowed scientists to compare before-and-after images.
Curtis McCully, a graduate student at Rutgers and lead author of the team’s paper, sharpened the Hubble pre-explosion images and noticed a peculiar object near the location of the supernova.
“I was very surprised to see anything at the location of the supernova. We expected the progenitor system would be too faint to see, like in previous searches for normal Type Ia supernova progenitors. It is exciting when nature surprises us,” McCully said.
After studying the object’s colors and comparing with computer simulations of possible Type Iax progenitor systems, the team concluded they were seeing the light of a star that had lost its outer hydrogen envelope, revealing its helium core.
The team plans to use Hubble again in 2015 to observe the area, giving time for the supernova’s light to dim enough to reveal any possible zombie star and helium companion to confirm their hypothesis.
“Back in 2009, when we were just starting to understand this class, we predicted these supernovae were produced by a white dwarf and helium star binary system,” said team member Ryan Foley of the University of Illinois at Urbana-Champaign, who helped identify Type Iax supernovae as a new class.
“There’s still a little uncertainty in this study, but it is essentially validation of our claim.”
One possible explanation for the unusual nature of SN 2012Z is that a game of seesaw ensued between the bigger and smaller of the star pair.
The more massive star evolved more quickly to expand and dump its hydrogen and helium onto the smaller star. The rapidly evolving star became a white dwarf. The smaller star bulked up, grew larger and engulfed the white dwarf.
The outer layers of this combined star were ejected, leaving behind the white dwarf and the helium core of the companion star. The white dwarf siphoned matter from the companion star until it became unstable and exploded as a mini-supernova, leaving behind a surviving zombie star.
Astronomers already have located the aftermath of another Type Iax supernova blast. Images were taken with Hubble in January 2013 of supernova 2008ha, located 69 million light-years away in the galaxy UGC 12682, in more than four years after it exploded.
The images show an object in the area of the supernova that could be the zombie star or the companion. The findings will be published in The Astrophysical Journal.
“SN 2012Z is one of the more powerful Type Iax supernovae and SN 2008ha is one of the weakest of the class, showing that Type Iax systems are very diverse,” explained Foley, lead author of the paper on SN 2008ha.
“And perhaps that diversity is related to how each of these stars explodes. Because these supernovae don’t destroy the white dwarf completely, we surmise that some of these explosions eject a little bit and some eject a whole lot.”
The astronomers hope their new findings will spur the development of improved models for these white dwarf explosions and a more complete understanding of the relationship between Type Iax and normal Type Ia supernovae and their corresponding star systems.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope.
The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
ASTRONOMERS FIND STREAM OF GAS–2.6 MILLION LIGHT YEARS LONG
From the FMS Global News Desk of Jeanne Hambleton Posted 07 August 2014 Royal Astronomical Society
Astronomers and students have found a bridge of atomic hydrogen gas 2.6 million light years long between galaxies 500 million light years away. They detected the gas using the William E. Gordon Telescope at the Arecibo Observatory, a radio astronomy facility of the US National Science Foundation sited in Puerto Rico. The team publish their results today in a paper in Monthly Notices of the Royal Astronomical Society.
The stream of atomic hydrogen gas is the largest known, a million light years longer than a gas tail found in the Virgo Cluster by another Arecibo project a few years ago. Dr Rhys Taylor, a researcher at the Czech Academy of Sciences and lead author of the paper, said “This was totally unexpected. We frequently see gas streams in galaxy clusters, where there are lots of galaxies close together, but to find something this long and not in a cluster is unprecedented.”
It is not just the length of the stream that is surprising but also the amount of gas found in it. Roberto Rodriguez, a 2014 graduate from the University of Puerto Rico in Humacao who worked on the project as an undergraduate, explained “We normally find gas inside galaxies, but here half of the gas – 15 billion times the mass of the Sun – is in the bridge. That is far more than in the Milky Way and Andromeda galaxies combined!”
The team is still investigating the origin of the stream. One notion surmises that the large galaxy at one end of the stream passed close to the group of smaller galaxies at the other end in the past, and that the gas bridge was drawn out as they moved apart. A second notion suggests that the large galaxy plowed straight through the middle of the group, pushing gas out of it. The team plan to use computer simulations to find out which of these ideas can best match the shape of the bridge that is seen with the Arecibo Telescope.
The project involved three undergraduate researchers: Roberto Rodriguez and Clarissa Vazquez from UPR Humacao, and Hanna Herbst, now a graduate student at the University of Florida.
Dr Robert Minchin, a staff astronomer at Arecibo Observatory and the principal investigator on the project, said “Student involvement is very important to us. We are proud to be inspiring the next generation of astronomers, and particularly proud of the involvement of Puerto Rican students.”
The bridge was found in data taken between 2008 and 2011 for the Arecibo Galaxy Environment Survey (AGES), which is using the power of the Arecibo Telescope to survey a large area of sky with a high level of sensitivity.
Astronaut Clayton Anderson inspires, organizes Iowa State workshop on spaceflight ops
From the FMS Global News Desk of Jeanne Hambleton Posted: 5-Aug-2014 Source Newsroom: Iowa State University
AMES, Iowa – The week’s objectives include scuba certification, wilderness survival, skydiving, flight simulation and a virtual visit to the International Space Station.
Those objectives are all part of an Iowa State University prototype workshop designed to give six students a taste of the operational aspects of spaceflight training and Iowa State educators a first look at preparing students for new employment opportunities in commercial spaceflight.
“We turn out excellent graduates at Iowa State in aerospace engineering, but they do not know how to think like an astronaut,” said Clayton Anderson, who retired from NASA in 2013 after two trips to the International Space Station, including a five-month tour of duty and six spacewalks. Anderson earned a master’s degree in aerospace engineering from Iowa State in 1983.
Anderson, now an Iowa State distinguished faculty fellow in aerospace engineering, has worked with Iowa State’s department of aerospace engineering to develop the prototype workshop in spaceflight operations.
The workshop will run seven days, 8 a.m. to 7 p.m., August 4-10. Six undergraduate students have been accepted (from 29 applicants) into the non-credit workshop, five from Iowa State and one from Tuskegee University in Alabama. Four of the students are men, two are women.
Anderson said the workshop will expose students to training programs similar to ones he completed as a NASA astronaut. Scuba diving, for example, will teach students how to work in a hazardous environment, while wilderness survival will teach mission planning, expeditionary behavior and teamwork.
Anderson also wants students to learn lessons in operational thinking. How, for example, could the space industry send tourists to space without requiring them to complete three years of spaceflight training? Or, how could engineers design controls and user interfaces so they are intuitive and easy to learn for a spacefaring neophyte?
Richard Wlezien, a professor and Iowa State’s Vance and Arlene Coffman Endowed Department Chair in Aerospace Engineering, said he is hoping this first workshop can eventually grow into a minor at the university.
Spaceflight, after all, is changing. Private companies are building and launching rockets. They are going to need people trained in spaceflight operations.
“We are at the beginning of commercial spaceflight,” Wlezien said.
“The next spacecraft ferrying cargo and astronauts to the International Space Station will be built, owned and operated by companies. Eventually, it will not be the responsibility of the federal government to train astronauts to fly these vehicles. There will have to be another path.
“We want to start thinking about educating people to be astronauts.”
Wlezien and Anderson said the idea for the spaceflight workshop came from a trip to the basement of Howe Hall, where there is a water tank that is 20 feet wide and 20 feet deep. It was originally designed for nondestructive testing of materials.
With a bit of imagination, the two saw the tank as a possible underwater training facility for would-be astronauts. Before long, Anderson was working with Tor Finseth, a graduate student in aerospace engineering and an aspiring astronaut, to develop a prototype program.
They have planned seven full days of learning, including lessons in the emerging spaceflight industry, decision analysis, leadership, spacecraft subsystems, space physiology and space suits. Plus, there are the lessons in scuba diving, wilderness survival, skydiving, flight simulation and virtual spaceflight.
Anderson already has some ideas to grow the program if it is offered again next summer.
“It is exciting to see the possibilities,” he said. “But we want to walk before we run – although I am ready to run
I will be back tomorrow with my feet on the ground. Jeanne