Cosmic Curiosity Reveals Ghostly Glow Of Dead Quasar

The green Voorwerp in the foreground remains illuminated by light emitted up to 70,000 years ago by a quasar in the center of the background galaxy, which has since died out. (Photo: WIYN/William Keel/Anna Manning)

by Staff Writers

New Haven CT (SPX) Nov 04, 2010

While sorting through hundreds of galaxy images as part of the Galaxy Zoo citizen science project two years ago, Dutch schoolteacher and volunteer astronomer Hanny van Arkel stumbled upon a strange-looking object that baffled professional astronomers.

Two years later, a team led by Yale University researchers has discovered that the unique object represents a snapshot in time that reveals surprising clues about the life cycle of black holes.

In a new study, the team has confirmed that the unusual object, known as Hanny's Voorwerp (Hanny's "object" in Dutch), is a large cloud of glowing gas illuminated by the light from a quasar-an extremely energetic galaxy with a supermassive black hole at its center.

The twist, described online in the Astrophysical Journal Letters, is that the quasar lighting up the gas has since burned out almost entirely, even though the light it emitted in the past continues to travel through space, illuminating the gas cloud and producing a sort of "light echo" of the dead quasar.

"This system really is like the Rosetta Stone of quasars," said Yale astronomer Kevin Schawinski, a co-founder of Galaxy Zoo and lead author of the study. "The amazing thing is that if it wasn't for the Voorwerp being illuminated nearby, the galaxy never would have piqued anyone's interest."

The team calculated that the light from the dead quasar, which is the nearest known galaxy to have hosted a quasar, took up to 70,000 years to travel through space and illuminate the Voorwerp-meaning the quasar must have shut down sometime within the past 70,000 years.

Until now, it was assumed that supermassive black holes took millions of years to die down after reaching their peak energy output.

However, the Voorwerp suggests that the supermassive black holes that fuel quasars shut down much more quickly than previously thought.

"This has huge implications for our understanding of how galaxies and black holes co-evolve," Schawinski said.

"The time scale on which quasars shut down their prodigious energy output is almost entirely unknown," said Meg Urry, director of the Yale Center for Astronomy and Astrophysics and a co-author of the paper.

"That's why the Voorwerp is such an intriguing-and potentially critical-case study for understanding the end of black hole growth in quasars."

Although the galaxy no longer shines brightly in X-ray light as a quasar, it is still radiating at radio wavelengths. Whether this radio jet played a role in shutting down the central black hole is just one of several possibilities Schawinski and the team will investigate next.

"We've solved the mystery of the Voorwerp," he said. "But this discovery has raised a whole bunch of new questions."

Other authors of the paper include Shanil Virani, Priyamvada Natarajan, Paolo Coppi (all of Yale University); Daniel Evans (Massachusetts Institute of Technology, Harvard-Smithsonian Center for Astrophysics and Elon University); William Keel and Anna Manning (University of Alabama and Kitt Peak National Observatory); Chris Lintott (University of Oxford and Adler Planetarium); Sugata Kaviraj (University of Oxford and Imperial College London); Steven Bamford (University of Nottingham); Gyula Jozsa (Netherlands Institute for Radio Astronomy and Argelander-Institut fur Astronomie); Michael Garrett (Netherlands Institute for Radio Astronomy, Leiden Observatory and Swinburne University of Technology); Hanny van Arkel (Netherlands Institute for Radio Astronomy); Pamela Gay (Southern Illinois University Edwardsville); and Lucy Fortson (University of Minnesota). Citation: Kevin Schawinski et al 2010 ApJ 724 L30 DOI: 10.1088/2041-8205/724/1/L30

spacedaily.com

Electrical malfunction delays Discovery launch to Thursday

by Staff Writers
Cape Canaveral, Florida (AFP)
An electrical malfunction has forced the US space agency to delay until Thursday the shuttle Discovery's final mission to the International Space Station, NASA said.

"Space shuttle Discovery's launch on the STS-133 mission has been delayed until no earlier than Thursday," NASA said in a statement.

The mission, initially scheduled for Monday, has been postponed three times.

Earlier delays were announced so that Kennedy Space Center technicians could repair quick-disconnect fittings in the system used to pressurize one of Discovery's orbital maneuvering rocket engines.

earlier related report
Shuttle Discovery counts down to final space voyage
Washington (AFP) Oct 31, 2010 - Discovery, the oldest space shuttle in NASA's fleet, is readying for its final mission Wednesday following repairs to leaks in a pressurization system that has twice delayed the launch.

"Work is on schedule. We completed flight pressurization and all went well. That is behind us now," Steve Payne, NASA test director, told reporters as the countdown to launch kicked off at 2:00 pm (1800 GMT) Sunday.

The mission, initially scheduled for Monday, was postponed so Kennedy Space Center technicians could repair quick-disconnect fittings in the system used to pressurize one of Discovery's orbital maneuvering rocket engines.

Discovery and its six American astronauts will now launch from Florida's Kennedy Space Center at 3:52 pm (1952 GMT) Wednesday bound for the International Space Station (ISS).

The weather forecast remains 70 percent for favorable conditions, Kathy Winters, Cape Canaveral's senior meteorologist, said at a press briefing, adding that there were slight concerns of possible rain and clouds in the launch area.

The flight to the orbiting ISS is the fourth and final shuttle flight of the year, and the last scheduled for Discovery, the oldest in the three-shuttle fleet that is being retired in 2011.

Discovery has been the busiest shuttle in history, with a record 38 trips into space since its first launch in 1984. According to NASA, it has traveled over 142 million miles (228 million kilometers) during that time, involving 5,628 orbits of the Earth over 351 days.

NASA has long relied on the Discovery spacecraft at key points along its 26-year career -- the launch of the Hubble Space Telescope in 1990, the first ever female shuttle pilot Eileen Collins in 1995, and in 1998 it carried US space icon John Glenn to become the oldest human to fly in space at age 77.

Its all-American crew on this voyage, including female mission specialist Nicole Stott, will deliver a pressurized logistics module called Leonardo, which will be permanently attached to the space station to give it more storage space.

The shuttle will also bring Robonaut 2, the first human-like robot in space, and a permanent addition to the orbiting space station, as well as spare parts.

Two space walks, for maintenance work and component installation, are scheduled.

The three US shuttles -- the other two are Atlantis and Endeavour -- are due to be sent off to become museum pieces after a final shuttle mission to the space station in late February.

That means Russian Soyuz spacecraft, a modernized version of which recently dropped off three fresh crew members to the ISS, doubling the crew to six, will for several years be the only vehicle for transporting humans into space.

However, NASA's recently approved 2011 budget has left the door open to an additional shuttle flight in June.

space-travel.com

China Goes To Mars

Mars Orbital Insertion will be a significant achievement for China's growing space science program.

by Morris Jones
Sydney, Australia (SPX) Oct 31, 2010
As China's second Moon probe continues its mission, more information is being disclosed about China's ambitions for worlds beyond. China has made no secret of its plans to explore Mars, but we are getting a firmer indication of what to expect.

Vague statements in the Chinese media have suggested that China could launch a mission to Mars in 2013. This is an interesting suggestion for a program that's still largely unknown to us. How does this add to our knowledge of China's Mars program?

China's first planned step to Mars is very well known. In 2011, the Yinghuo 1 orbiter will be launched to Mars in tandem with Russia's Phobos-Grunt mission. We know a lot about Yinghuo 1 already, thanks to some fairly open publicity about the mission. Yinghuo 1 is a small orbiter, which will enter a highly elliptical orbit around Mars.

Its main role is to study the tenuous Martian atmosphere, and help to answer one of the greatest mysteries surrounding the planet. Long ago, the atmosphere of Mars was much thicker, helping to produce almost Earthlike conditions on the surface. Why did Mars change into the barren world of today, and why did most of the atmosphere disappear?

Roughly two years after Yinghuo 1 is launched, a new "launch window" will open between Earth and Mars, as the position of the planets becomes favourable again. NASA plans to send an orbiter during this window, and it will also study the Martian atmosphere. Could China be ready to fly again so soon?

There are plenty of reasons to believe that China could do it. Consider recent events. China has successfully carried out a long mission in deep space. The Chang'e 1 mission was China's first lunar orbiter. Launched in 2007, the spacecraft performed well in mapping the entire Moon.

China has followed this with the launch of Chang'e 2 just a few weeks ago. This spacecraft is essentially a copy of Chang'e 1, with different instruments and some improvements to its sub-systems. Chang'e 2 is performing very well, and has navigated successfully into a low lunar orbit. Chinese space engineers must feel pleased. They've developed a generic spacecraft design and proven that it works well, on two flights out of two.

China has also openly discussed the possibility of sending Chang'e 2 beyond the Moon once its primary mission is complete. While the spacecraft will not be sent to Mars, it has been suggested that Chang'e 2 could be sent into heliocentric orbit, to test communications and control at vast distances from Earth. This is another hint at what China is planning.

This author suggests that the basic spacecraft bus used for the Chang'e lunar orbiters could be modified for use as a Chinese Mars probe. The Chang'e bus, or main spacecraft body, is itself derived from a geostationary communications satellite. Engineers love evolution, taking something that works and modifying it for other purposes. From Earth orbit, to the Moon, to Mars, is the steady path of this robust spacecraft design.

A dedicated Mars mission would require further modifications to the design of the spacecraft. There would need to be changes to the antennas and telemetry systems used, to compensate for the greater distance. One of the changes in Chang'e 2 over its predecessor is the use of a new, advanced radio system with different frequencies. Could this be a precursor of something designed to work at Mars?

Flying to the Moon is, technically speaking, a trip into deep space. But a flight all the way to Mars could expose a spacecraft to even more hazards. The spacecraft could probably use some additional hardening of some of its key components, even if this is just placing extra cosmic ray shielding on the computer.

Getting to Mars requires more energy than a mission to the Moon. China used the Long March 3A for the first Chang'e launch, and then switched to the more powerful Long March 3C for the second. But even this rocket would struggle to send a Chang'e-type probe to Mars.

It's entirely possible, however, that the Long March 3B could do it. Despite its lower alphabetical rank, this rocket is more powerful than the 3A or 3C, and draws much of its extra force from the use of four strap-on rocket boosters. If China really wanted a big boost, it could use the stretched variant of this rocket, the Long March 3B/E.

Right now, this is the most powerful booster in China's fleet. More powerful boosters will be available to China when the Long March 5 family of boosters makes its debut, but this is unlikely to happen before 2014. If China wants to fly to Mars in 2013, the well-tested Long March 3B will be the best choice.

So, we have a rocket that can reach Mars and a spacecraft design that can fly there. What else needs to be addressed? China has a large stable of scientific instruments at its disposal. Some have been tested on the Chang'e missions. Some are already going to Mars on board Yinghuo.

A large Mars orbiter will need a high-resolution camera (currently on Chang'e 2), spectrometers (Chang'e 1 and 2) and some particles and fields instruments (Yinghuo 1 and various Chinese scientific satellites). China just needs to pick and choose.

Then there's the tracking and support. China has already demonstrated the ability to track and communicate with spacecraft at the Moon. Through its co-operation with the European Space Agency, it has access to a global deep space network, and can also tap European experience in tracking planetary missions. Control and navigation of both Chang'e missions was impressive.

When all the recent progress in China's unmanned space program is considered, the idea of launching an advanced Mars mission within three years does not sound farfetched. But China could elect to wait for another launch window, and refine some of its mission goals and hardware.

There are also ambitious feats in the works for China's lunar program, with a robot lunar landing expected in 2012. China is also planning its first small manned space laboratory, which should also receive its first crew in 2012. There's plenty of activity in the near future without going to Mars.

Even if China does not launch its second Mars mission in 2013, the very fact that it can be considered is instructive. It points to a growing confidence in China's spaceflight capabilities, and also gives hints to the type of hardware that would probably be used. As usual, time will reveal the answers to these questions.

www.spacedaily.com