New Map of Debris Around the Milky Way

Image credit: University of Virginia

A new survey of the stars surrounding the Milky Way has produced a detailed map of how streams of stars and debris are being added to our galaxy. Researchers from the University of Virginia used data from the 2MASS sky survey to map out the Sagittarius galaxy which wraps around the Milky Way in a long stream of stars. They were able to distinguish between galaxies because a certain class of stars, called M giants, are much more common in Sagittarius – when they tuned their search to just look for these stars, Sagittarius “popped into view”.

Thousands of stars stripped from the nearby Sagittarius dwarf galaxy are streaming through our vicinity of the Milky Way galaxy, according to a new view of the local universe constructed by a team of astronomers from the University of Virginia and the University of Massachusetts.

Using volumes of data from the Two-Micron All Sky Survey (2MASS), a major project to survey the sky in infrared light led by the University of Massachusetts, the astronomers are answering questions that have baffled scientists for decades and proving that our own Milky Way is consuming one of its neighbors in a dramatic display of ongoing galactic cannibalism. The study, to be published in the Dec. 20 issue of the Astrophysical Journal, is the first to map the full extent of the Sagittarius galaxy and show in visually vivid detail how its debris wraps around and passes through our Milky Way. Sagittarius is 10,000 times smaller in mass than the Milky Way, so it is getting stretched out, torn apart and gobbled up by the bigger Milky Way.

“It’s clear who’s the bully in the interaction,” said Steven Majewski, U.Va. professor of astronomy and lead author on the paper describing the results.

In model images made to show the interaction in 3-D, available at, the Milky Way appears as a flattened disk with spiral arms, while Sagittarius is visible as a long flourish of stars swirling first under and then over and onto the Milky Way disk.

“If people had infrared-sensitive eyes, the entrails of Sagittarius would be a prominent fixture sweeping across our sky,” Majewski said. “But at human, visual wavelengths, they become buried among countless intervening stars and obscuring dust. The great expanse of the Sagittarius system has been hidden from view.”

Not any more. By using infrared maps, the astronomers filtered away millions of foreground stars to focus on a type of star called an M giant. These large, infrared-bright stars are populous in the Sagittarius galaxy but uncommon in the outer Milky Way. The 2MASS infrared map of M giant stars analyzed by Majewski and collaborators is the first to give a complete view of our galaxy’s meal of Sagittarius stars, now wrapping like a spaghetti noodle around the Milky Way. Prior to this work, astronomers had detected only a few scattered pieces of the disrupted Sagittarius dwarf. Even the existence of Sagittarius was unknown until the heart of this nearest satellite galaxy of the Milky Way was discovered by a British team of astronomers in 1994.

“We sifted several thousand interesting stars from a catalog of half a billion,” said co-author Michael Skrutskie, U.Va. professor of astronomy and principal investigator for the 2MASS project. “By tuning our maps of the sky to the ‘right’ kind of star, the Sagittarius system jumped into view.”

“This first full-sky map of Sagittarius shows its extensive interaction with the Milky Way,” Majewski said. “Both stars and star clusters now in the outer parts of the Milky Way have been ‘stolen’ from Sagittarius as the gravitational forces of the Milky Way nibbled away at its dwarf companion. This one vivid example shows that the Milky Way grows by eating its smaller neighbors.”

“Astronomers used to view galaxy formation as an event that happened in the distant past,” noted David Spergel, a professor of astrophysics at Princeton University after viewing the new finding. “These observations reinforce the idea that galaxy formation is not an event, but an ongoing process.”

The study’s map of M giants depicts 2 billion years of Sagittarius stripping by the Milky Way, and suggests that Sagittarius has reached a critical phase in what had been a slow dance of death.

“After slow, continuous gnawing by the Milky Way, Sagittarius has been whittled down to the point that it cannot hold itself together much longer,” said 2MASS Science Team member and study co-author Martin Weinberg of the University of Massachusetts. “We are seeing Sagittarius at the very end of its life as an intact system.”

Does this mean we are at a unique moment in the life of our galaxy? Yes and no.

“Whenever possible, astronomers appeal to the principle that we are not at a special time or place in the universe,” Majewski said. “Because over the 14 billion-year history of the Milky Way it is unlikely that we would just happen to catch a brief event like the death of Sagittarius, we infer that such events must be common in the life of big spiral galaxies like our own. The Milky Way probably dined on a number of dwarf galaxy snacks in the past.”

On the other hand, Majewski and his colleagues have been surprised by the Earth’s proximity to a portion of the Sagittarius debris.

“For only a few percent of its 240 million-year orbit around the Milky Way galaxy does our Solar System pass through the path of Sagittarius debris,” Majewski said. “Remarkably, stars from Sagittarius are now raining down onto our present position in the Milky Way. Stars from an alien galaxy are relatively near us. We have to re-think our assumptions about the Milky Way galaxy to account for this contamination.”

The new findings will help astronomers measure the total mass of the Milky Way and Sagittarius galaxies, and probe the quantity and distribution of the invisible dark matter in these systems.

“The shape of the Sagittarius debris trail shows us that the Milky Way’s unseen dark matter is in a spherical distribution, a result that is quite unexpected,” Weinberg said.

“The observations provide new insights into the nature of the mysterious dark matter,” said Princeton’s Spergel. “Either our galaxy is unusual or the dark matter has richer properties than postulated by conventional models.”

2MASS was a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology. The National Aeronautics and Space Administration, and the National Science Foundation funded the project. Additional funding for the Sagittarius study with 2MASS came from the David and Lucile Packard Foundation and the Research Corporation.

Original Source: University of Virginia News Release

A Few Small Changes

I made a couple of improvements to Universe Today yesterday, including “Printer-friendly pages”. At the bottom of any article on the site now is a link to a printer version of the article. I’ve done a couple of tests and it looks pretty good on my laser printer. Please let me know if you have any problems with it.

A bigger change, however, is that I’m going to be moving the site to a dedicated server in the next few days. It’s a pretty big time commitment, so there might be some delays.

Oh, and I removed that black background on the newsletter – it was making it difficult for people to just reply to the newsletter if they wanted to send me an email. And I like to receive email. 🙂


Fraser Cain
Universe Today

Small Telescope Helps Make Observations on Titan

Image credit: NASA

Sarah Horst, a planetary sciences major at Caltech, helped astronomers track cloud formations on Saturn’s moon Titan using only a fourteen inch telescope – in Los Angeles. Researchers needed a way to track Titan night after night for several months, but no large observatory could provide this much time to carry out detailed observations. Horst set up an old teaching telescope to track the intensity of light coming from Titan. Whenever something unusual happened, her associates would contact Keck for detailed photographs.

Meet Sarah Horst, throwback. The planetary science major, a senior at the California Institute of Technology, spent six months engaged in a bit of old-time telescope observing. The work led to some breakthrough research about Saturn’s moon Titan, and indirectly led to funding for a new telescope at Caltech’s Palomar Observatory.

Horst, 21, was looking for a part-time job in the summer of her sophomore year, and was hired by Mike Brown, an associate professor of planetary astronomy. Brown and graduate student Antonin Bouchez knew there had been previous evidence of “weather” on Titan in the form of clouds. But that evidence was elusive. “Someone would look one year and think they saw a cloud, then look the next year and not see a cloud,” explains Brown. “What we were after was a way to look at Titan, night after night after night.”

The problem, of course, is that all of the large telescopes like Keck are incredibly busy, booked by astronomers from around the world who use the precious time for their own line of research. So Brown and Bouchez knew that obtaining large amounts of time for a single project like this was not going to happen.

The solution: Use an old teaching telescope–the hoary 14-inch Celestron telescope located on top of Caltech’s Robinson Lab–to do cutting edge science that couldn’t be done at the largest telescopes in the world, in Hawaii.

Though the power of the Robinson telescope is weak, and light pollution from Pasadena strong, which prevents imaging the actual clouds, the light reflecting from clouds could be imaged (the more clouds, the more light that’s reflected). All that was needed was someone who could come night after night and take multiple images.

Enter Horst, the self-described “lowly undergraduate.” For months, Horst spent her evenings in Robinson. “I did the setup, which involved a wheel that contained four light filters,” she explains. Each filter would capture a different wavelength of light. Software switched the filters; all she had to do, says Horst, was to orientate and focus the telescope.

Now, modern-day astronomers have it relatively easy when using their telescope time. Sure they’re up all night, but they sit on a comfortable chair in a warm room, hot coffee close at hand, and do their observing through a computer monitor that’s connected to a telescope.

Not Horst. She did it the old way, in discomfort. “A lot of times in December or January I’d go in late at night, and it would be freezing,” says Horst, who runs the 800-meter for the Caltech track team. “I’d wrap myself up in blankets.” Horst spent hours in the dark, since the old dome itself had to be dark. “I couldn’t even study,” she says, “although sometimes I tried to read by the light of the moon.”

A software program written by Bouchez plotted the light intensity from each image on a graph. When a particular image looked promising, Bouchez contacted Brown. As a frequent user of the Keck Observatory, which is powerful enough to take an image of the actual clouds, Brown was able to call colleagues who were using the Keck that night and quickly convince them that something exciting was going on. “It only took about ten minutes to get a quick image of Titan,” says Brown. “The funny part was having to explain to them that we knew there were clouds because we had seen the evidence in our 14-inch telescope in the middle of the L.A. basin.”

The result was “Direct Detection of Variable Tropospheric Clouds Near Titan’s South Pole,” which appeared in the December 19 journal Nature. It included this acknowledgement: “We thank . . . S. Horst for many nights of monitoring Titan in the cold.”

The paper has helped Brown obtain the funding to build a new 24-inch custom-built telescope. It will be placed in its own building atop Palomar Mountain, on the grounds of Caltech’s existing observatory. It’s also roboticized; Brown will control the scope from Pasadena via a computer program he has written.

He’ll use it for further observation of Titan and for other imaging, as well, such as fast-moving comets. “Most astronomy is big,” notes Brown; “big scopes looking at big, unchanging things, like galaxies. I like to look at changing things, which led to this telescope.”

What really made this project unique, though, according to Brown, is the Robinson scope. “Sarah was able to do something with this little telescope in Pasadena that no one in the world, on any of their larger professional telescopes on high, dark mountaintops, had been able to do,” he says. “Sometimes a good idea and stubbornness are better than the largest telescope in town.”

For Horst, while the work wasn’t intellectually challenging–“a trained monkey could have done it,” she says with a laugh–it was, nonetheless, “a cool project. Everything here is so theoretical and tedious, and so classroom orientated. So in that way it was a nice experience and reminded me what real science was about.”

Original Source: Caltech News Release

Sea Launch Heads Out for Next Launch

Image credit: Sea Launch

The Sea Launch Commander and the Odyssey launch platform headed out to sea on Monday, beginning the journey to reach the equator in the Pacific Ocean. This time around, Sea Launch will be launching the Galaxy XIII/Horizons-1 satellite on board a three-stage Zenit 3SL rocket. The launch window begins at 0403 GMT October 1 (12:03 am EDT). Once it reaches geosynchronous orbit, the satellite will provide digital video, Internet and data services to North America.

The Odyssey Launch Platform and the Sea Launch Commander have embarked on their transit to the Equator for the launch of the Galaxy XIII/Horizons-1 satellite for PanAmSat Corporation and JSAT Corporation. Liftoff is scheduled for September 30, during a 39-minute launch window that opens at 9:03 pm PDT (4:03:00 GMT, October 1).

The Sea Launch vessels are sailing from Sea Launch Home Port, in the Port of Long Beach, Calif., to the launch site on the Equator at 154? West Longitude. Upon arrival, the launch team will initiate a 72-hour countdown, ballasting the Launch Platform to launch depth and performing final tests on the rocket and spacecraft. The three-stage Zenit-3SL rocket will lift the 4090 kg (9,081 lb) Galaxy XIII/Horizons-1 satellite to geosynchronous transfer orbit. This is the third mission Sea Launch is executing for PanAmSat, having previously launched PAS-9 in July 2000 and Galaxy IIIC in June 2002.

The Boeing-built 601 HP spacecraft is designed to offer a variety of digital video, Internet and data services to North America, Central America, Alaska and Hawaii. The spacecraft’s Ku-band payload, designated Horizons-1, supports the Horizons joint venture of PanAmSat and JSAT. This venture provides expanded Ku-band services in North America and extended services to Japan and Asia via a Hawaii-based relay station. The C-band portion is known as Galaxy XIII and will be operated separately as part of PanAmSat’s Galaxy cable neighborhood, which serves the U.S. cable industry.

Sea Launch Company, LLC, headquartered in Long Beach, Calif., is a world leader in providing heavy-lift commercial launch services. This multinational partnership offers the most direct and cost-effective route to geostationary orbit. With the advantage of a launch site on the Equator, the reliable Zenit-3SL rocket can lift a heavier spacecraft mass or provide longer life on orbit, offering best value plus schedule assurance. Sea Launch has a current backlog of 15 firm launch contracts. For additional information and live coverage of this mission, visit the Sea Launch website at:

Note to editors: Sea Launch will carry a live satellite feed and streaming video of the entire mission on the day of launch. We will post transponder coordinates as well as additional information and high resolution images on a media site at:

Original Source: Boeing News Release

Orbital Space Plane Review Completed

NASA’s Orbital Space Plane program reached an important milestone this week with the completion of its Level 1 requirements review. The review evaluated designs from several contractors for a spacecraft which will provide crew rescue and transfer of personnel to and from the International Space Station. This review was to ensure the proposed vehicles are safe, reliable, affordable, and can be maintained. The review team has also put forth their Level 2 requirements, which are much detailed and describe many features that the proposed designs must include.

NASA’s Orbital Space Plane program has successfully completed its Systems Requirements Review to evaluate the concept design of the nation?s next space vehicle ? aimed at providing crew rescue and transfer for the International Space Station. In addition, the review set Level II requirements ? guidelines that further narrow the scope of the system design.

NASA’s Orbital Space Plane (OSP) program is one step closer to becoming the nation’s next space vehicle with the successful completion of its Systems Requirements Review. The review evaluated the vehicle’s concept design for providing crew rescue and transfer for the International Space Station.

The NASA-led review evaluated contractor designs based on the primary design criteria, or Level 1 requirements, set by the agency in February. The contractor teams designing the OSP, The Boeing Company, Seal Beach, Calif.; Lockheed Martin, Denver; and a team including Orbital Sciences Corp., Dulles, Va., and Northrop Grumman, El Segundo, Calif., have been working to develop system specifications, including systems analysis, trade studies, and concept feasibility in preparation for the review.

The System Requirements Review includes analysis of requirements and supporting technical documentation to ensure the system is safe, reliable, maintainable and affordable. It is one in a series of reviews that occurs before the Orbital Space Plane system is built.

In addition, the review set Level 2 requirements, guidelines that further narrow the scope and add a level of detail to the system design. The Level 2 requirements address guidelines for safety, launch, emergency-return and crew-transfer missions, mission frequency, on-orbit mission duration, contingency cargo requirements, and docking and interfacing with the Space Station. The requirements also include limits on the gravitational loads on the crew, health monitoring of the crew, communications with the Space Station and mission control on Earth, reliability, system lifetime, and logistics. Each level of requirements provides a narrower parameter for the design of the vehicle system.

“This review is a critical step in making the Orbital Space Plane a reality,” said Dennis Smith, Orbital Space Plane program manager. “These requirements are the instruction manual for designing the entire system that will provide safe, reliable access to and from the International Space Station,” he said.

The Level 2 requirements are contained in a package of technical documents and plans, which include the Orbital Space Plane Systems Requirements Document, the International Space Station Interface Requirements Document, the Orbital Space Plane to Expendable Launch Vehicle Interface Definition Document, and the Orbital Space Plane Human Rating Plan, along with other reference and guidance documentation. An executive summary of the Level 2 requirements is on the OSP Web site. Following review of the documentation for export-control and security issues, the Level 2 documentation also will be available online.

A System Definition Review is scheduled for November 2003. It will include a further, more focused evaluation of the concept design including risk reduction and breakdown of the functional elements of the system based on the Level 2 requirements. The review also will set Level 3 requirements for the Orbital Space Plane system based on evaluation of the program objectives and contractor feedback.

The program is scheduled to issue a request for proposal to the three contractor teams in November 2003. A decision to develop a full-scale vehicle system is expected in 2004.

For the executive summary and other information about the Orbital Space Plane, visit:

Original Source: NASA News Release

New Areas in the Forum

I’ve added a couple of new areas to the Universe Today Forums which I think will be pretty helpful. The first is a Totally Off-Topic area where people can yack about stuff that has nothing to do with space and astronomy. Hopefully that will keep the rest of the forums purely about space.

A more useful area, however, is “Questions and Answers“. If you’ve got a nagging question about space or a current mission, go ahead and ask it here. People in the forum will try and help you out, and I’ll also be submitting the really tough questions to experts in space and astronomy so we can help get to the bottom of this for you.

Come and join us!

Fraser Cain
Universe Today

P.S. Thanks to the overwhelming number of you who replied to my last email. There’s definitely an email delay to some of you. I’m working with my hosting provider to get to the bottom of this.

Madhavan Nair Selected as New Chairman of ISRO

Image credit: ISRO

Mr. G Madhavan Nair has been appointed as the new Chairman of the Indian Space Research Organization (ISRO). Previous to this new position, Nair was the Director of Vikram Sarabhai Space Centre, and has been involved in the agency since 1967 when he was first hired at the Thumba Equatorial Rocket Launching Station. His predecessor, Dr K Kasturirangan, left the position after he was nominated for India’s Upper House of Parliament.

The Appointments Committee of the Cabinet has appointed Mr G Madhavan Nair as Secretary, Department of Space, Chairman Space Commission and Chairman, ISRO. Mr Madhavan Nair, who was Director, Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, was holding additional charge of these posts since September 1, 2003 after Dr K Kasturirangan relinquished the office consequent to the President of India nominating him as Member of Rajya Sabha (Upper House of Parliament).

Mr Madhavan Nair is a leading technologist in the field of Rocket Systems. He has made significant contributions to the development of multistage Satellite Launch Vehicles for the Indian space programme. As Director, VSSC, he has led research and development in the area of satellite launch vehicles for orbiting spacecraft for remote sensing and communications.

After graduating in Engineering from Kerala University in 1966, Mr Madhavan Nair underwent training at Bhabha Atomic Research Center (BARC), Mumbai, and joined Thumba Equatorial Rocket Launching Station (TERLS) in 1967. Since then, he has held various positions posting illustrious milestones on his way to the present position. He made impressive contributions to the first Indian Satellite Launch Vehicle, SLV-3. Subsequently, as Project Director, he brought to fruition the development of India’s first operational Satellite Launch Vehicle, PSLV. With six successful launches so far, PSLV has convincingly demonstrated its reliability for not only launching multiple satellites including placing them in different orbits in a single launch but also its capability to place satellites in Geo-synchronous Transfer Orbit (GTO). PSLV is also proposed for launching India’s unmanned lunar craft under Chandrayaan-1 mission. Mr Madhavan Nair, also contributed to the indigenous development of cryogenic technology and as Dire
ctor, Liquid Propulsion Systems Centre during 1995-99, he gave concrete shape for the vital infrastructure for its development.

Mr Madhavan Nair took over as the Director of VSSC in 1999 and in the following two years led the successful flight of GSLV in the very first attempt followed by another successful flight in May 2003. GSLV has since been commissioned into operational service for launching 2000 kg class satellites into GTO.

Mr Madhavan Nair has been the leader of the Indian delegation to the United Nations Committee on Peaceful Uses of Outer Space (UN-COPUOS). He has received several prestigious awards including Shri Om Prakash Bhasin Award, Swadeshi Sastra Puraskar Award, FIE Foundation Award and Vikram Sarabhai Memorial Gold Medal of ISCA. He was conferred ‘Padma Bhushan’ by the President of India in 1998.

The outgoing Chairman of ISRO, Dr K Kasturirangan, saw during his tenure of nearly a decade, the Indian space programme witnessing several major milestones including the commissioning of India’s prestigious launch vehicle, the Polar Satellite Launch Vehicle (PSLV) and more recently, the commissioning of all important Geo-synchronous Satellite Launch Vehicle (GSLV). Further, the world’s best civilian remote sensing satellites, IRS-1C and 1D, experimental remote sensing satellites, IRS-P2 and IRS-P3, besides
an exclusive ocean observation satellite IRS-P4 were launched. A 1-m spatial resolution experimental satellite, TES, was also built and launched during his tenure. He also saw the launching of second generation INSAT satellites that vastly enhanced the capacity of INSAT system for telecommunication, television broadcasting and meteorology. Three satellites under the third generation series, INSAT-3A, INSAT-3B, and INSAT-3C were also launched besides an exclusive meteorological satellite, KALPANA-1. He chaired some of the prestigious international committees, such as, the International Committee on Earth Observation Satellites (CEOS), Panel for Space Research in Developing countries of COSPAR/ICSU, and the committee meeting at senior official level of UN-ESCAP, that led to the adoption of the “Delhi Declaration” by the Ministers of the region (1999-2000).

Dr B N Suresh is the new Director of VSSC. Dr B N Suresh, Outstanding Scientist at ISRO’s Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, has been appointed as the Director of the Centre and he took over charge on September 20, 2003 from Mr Madhavan Nair. Dr Suresh joined ISRO in July 1969 and is an expert in control and guidance systems. He has made significant contributions to the design and development of all satellite launch vehicles of ISRO – SLV-3, ASLV, PSLV and GSLV.

Original Source: ISRO News Release

Brown Dwarf is Actually a Binary System

Image credit: Gemini

Astronomers were searching for planets around nearby star Epsilon Indi when they discovered something unusual. A previously-known brown dwarf star orbiting Epsilon Indi has a companion of its own. This new companion, known as Epsilon Indi Bb, orbits the larger brown dwarf (Epsilon Indi Ba) at a distance of only 2.2 astronomical units. Both objects are part of a new class of stars called T-dwarfs; they have diameters similar to Jupiter but have significantly more mass.

While searching for planet-sized bodies that might accompany the nearby star system Epsilon Indi, astronomers using the Gemini South telescope in Chile made a related but unexpected detection.

Widely observed by telescopes on the ground and in space, Epsilon Indi was known to host an orbiting companion, called Epsilon Indi B, which was discovered last year and is the nearest known specimen of a brown dwarf. Brown dwarfs are very small, cool stars thirty to forty times more massive than Jupiter but of similar size. Despite all the observing, it took the combination of Gemini’s powerful infrared capabilities and the extremely sensitive spectrograph/imager called PHOENIX (without adaptive optics) to reveal the more elusive body.

“Epsilon Indi Ba is the closest confirmed brown dwarf to our solar system,” says Dr. Gordon Walker (University of British Columbia, Vancouver, Canada), who led the research team that includes Dr. Suzie Ramsay Howat (UK Astronomy Technology Centre, Edinburgh, UK). Dr. Walker explains, “With the detection of Epsilon Indi Bb, we now know that Epsilon Indi Ba has a close companion that appears to be another, even cooler brown dwarf. One certainty is that the Epsilon Indi system is even more interesting than we previously thought.”

The team of scientists who detected Epsilon Indi Bb using the Gemini South Telescope on Cerro Pach?n, Chile, were the first to report this finding, which was published in the IAU Circular Volume 8818. Subsequently, the VLT (Very Large Telescope) announced that scientists had actually observed the object five days earlier (using adaptive optics), and their finding is reported at

“When the target was acquired and we saw that there were clearly two objects close together, we initially thought it must be the wrong object. Epsilon Indi Ba, formerly called Epsilon Indi B, had been observed before and in those observations, no one noticed the companion object. It was a tremendous surprise for us,” says Dr. Kevin Volk (Gemini Observatory, La Serena, Chile) who was actually making the observation at the Gemini South telescope along with Dr. Robert Blum (CTIO, La Serena, Chile).

The serendipitous nature of the detection took the science team–whose members are from Canada, the U.K., the U.S. and Chile–by surprise. Dr. Blum elaborates, “We then found that the companion, named Epsilon Indi Bb, is invisible in the methane band where previous Gemini observations had been taken. The coolest brown dwarfs are very faint and hard to detect, but there may be vast numbers of them–which makes this detection important.”

Epsilon Indi is the fifth brightest star in the southern constellation of Indus and is located about 11.8 light years away from our solar system. The star is similar to but cooler than our sun. The projected separation as seen on the sky between Epsilon Indi and Indi Ba is approximately 1500 AUs (one AU or Astronomical Unit is the average distance between the Earth and the Sun or about 93 million miles/150 million kilometers), and the distance between Epsilon Indi Ba and the newly discovered Epsilon Indi Bb is at least 2.2 AUs.

“Because this system is so close to us, it appears to move quite rapidly in the sky,” says Dr. Volk. “We were able to confirm our detection–and rule out a more distant background object–within a few weeks since we could detect the motion of the system relative to the background stars relatively quickly.”

As the facts surrounding the detection become clearer with additional spectroscopic data, the research team expects that important details about Epsilon Indi Bb will be revealed. “Unfortunately, the window for observing this system is nearly closed for this year, so we will have to wait until early next year when we can see this system again in the morning sky,” says Dr. David Balam (University of Victoria, Canada).

The data recently obtained from Gemini show that Epsilon Indi Bb is cooler and less massive than Epsilon Indi Ba as demonstrated by its significantly lower brightness and deep methane absorption. Methane absorption is a key indicator for low mass objects since gaseous methane can only exist in the lower temperature environments of the atmospheres of brown dwarfs and planets where the gas can exist.

“Methane absorption was the key to the detection,” says Dr. Walker, “because Dr. Volk happened to catch sight of Epsilon Indi Bb through one of the ‘windows’ between the methane absorption bands. Because the absorption bands block longer wavelength infrared light, Epsilon Indi Bb was visible when viewed at shorter infrared wavelengths.”

Epsilon Indi Ba and Bb are members of a recently discovered type of astronomical object–the “T” class brown dwarfs. These T-dwarfs have diameters approximately equal to Jupiter but with more mass. Spectra of Epsilon Indi Ba, taken with PHOENIX by Dr. Verne Smith (University of Texas, El Paso) and collaborators, show the Epsilon Indi Ba has 32 times the mass of Jupiter and a 1500-degree surface temperature. It is spinning about three times faster than Jupiter. Epsilon Indi Bb has less mass, is cooler, but is still much more massive and hotter than Jupiter. Like Jupiter, the T-dwarfs do not have enough mass to make energy the way the sun does from nuclear fusion. Epsilon Indi Ba and Bb are glowing from heat resulting from the mass pushing down on the interior.

PHOENIX, the instrument that is responsible for producing the data, is a near-infrared, high-resolution spectrometer that was built by the National Optical Astronomy Observatory (NOAO) in Tucson, Arizona, and was commissioned on Gemini South in 2001. Dr. Ken Hinkle (NOAO, Tucson, Arizona) said, “PHOENIX was designed for exactly this type of research. It is the first high-resolution infrared spectrograph on a Gemini telescope, and the first high-resolution infrared spectrograph on any southern hemisphere telescope.”

Dr. Phil Puxley, Associate Director of Gemini South, adds, “Gemini’s infrared optimization makes the 8-meter twin telescopes ideal for capturing such serendipitous discoveries. Finds like this are exactly what Gemini is designed to do and this sort of exciting work demonstrates the potential of Gemini’s science.”

Epsilon Indi is visible with the naked eye from June to December in the southern hemisphere. It can be detected with the locator map available at, which also contains other images and illustrations.

The Gemini Observatory is an international collaboration that has built two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located at Mauna Kea, Hawai`i (Gemini North) and the other telescope at Cerro Pach?n in central Chile (Gemini South), and hence provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in each partner country with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the Canadian National Research Council (NRC), the Chilean Comisi?n Nacional de Investigaci?n Cientifica y Tecnol?gica (CONICYT), the Australian Research Council (ARC), the Argentinean Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) and the Brazilian Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq). The Observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

Original Source: Gemini News Release

Galileo Plunges Into Jupiter

Image credit: NASA/JPL

NASA’s Galileo spacecraft was intentionally crashed into Jupiter on Sunday, ending 14 years of service to science and exploration. The spacecraft entered Jupiter’s thick atmosphere and disintegrated at 1857 GMT (2:57pm EDT), but the last signals arrived at Earth nearly an hour later because of the great distance to Jupiter. At the end of its mission, Galileo lacked the fuel to escape the Jovian system so scientists decided to crash it into Jupiter to avoid contaminating any potential life on Europa, which is believed to have liquid water oceans under a thick sheet of ice.

The Galileo spacecraft’s 14-year odyssey came to an end on Sunday, Sept. 21, when the spacecraft passed into Jupiter’s shadow then disintegrated in the planet’s dense atmosphere at 11:57 a.m. Pacific Daylight Time. The Deep Space Network tracking station in Goldstone, Calif., received the last signal at 12:43:14 PDT. The delay is due to the time it takes for the signal to travel to Earth.

Hundreds of former Galileo project members and their families were present at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., for a celebration to bid the spacecraft goodbye.

“We learned mind-boggling things. This mission was worth its weight in gold,” said Dr. Claudia Alexander, Galileo project manager.

Having traveled approximately 4.6 billion kilometers (about 2.8 billion miles), the hardy spacecraft endured more than four times the cumulative dose of harmful jovian radiation it was designed to withstand. During a previous flyby of the moon Amalthea in November 2002, flashes of light were seen by the star scanner that indicated the presence of rocky debris circling Jupiter in the vicinity of the small moon. Another measurement of this area was taken today during Galileo’s final pass. Further analysis may help confirm or constrain the existence of a ring at Amalthea’s orbit.

“We haven’t lost a spacecraft, we’ve gained a steppingstone into the future of space exploration,” said Dr. Torrance Johnson, Galileo project scientist.

The spacecraft was purposely put on a collision course with Jupiter because the onboard propellant was nearly depleted and to eliminate any chance of an unwanted impact between the spacecraft and Jupiter’s moon Europa, which Galileo discovered is likely to have a subsurface ocean. Without propellant, the spacecraft would not be able to point its antenna toward Earth or adjust its trajectory, so controlling the spacecraft would no longer be possible. The possibility of life existing on Europa is so compelling and has raised so many unanswered questions that it is prompting plans for future spacecraft to return to the icy moon.

Galileo was launched from the cargo bay of Space Shuttle Atlantis in 1989. The exciting list of discoveries started even before Galileo got a glimpse of Jupiter. As it crossed the asteroid belt in October 1991, Galileo snapped images of Gaspra, returning the first ever close-up image of an asteroid. Less then a year later, the spacecraft got up close to yet another asteroid, Ida, revealing it had its own little “moon,” Dactyl, the first known moon of an asteroid. In 1994 the spacecraft made the only direct observation of a comet impacting a planet– comet Shoemaker-Levy 9’s collision with Jupiter.

The descent probe made the first in-place studies of the planet’s clouds and winds, and it furthered scientists’ understanding of how Jupiter evolved. The probe also made composition measurements designed to assess the degree of evolution of Jupiter compared to the Sun.

Galileo made the first observation of ammonia clouds in another planet’s atmosphere. It also observed numerous large thunderstorms on Jupiter many times larger than those on Earth, with lightning strikes up to 1,000 times more powerful than on Earth. It was the first spacecraft to dwell in a giant planet’s magnetosphere long enough to identify its global structure and to investigate the dynamics of Jupiter’s magnetic field. Galileo determined that Jupiter’s ring system is formed by dust kicked up as interplanetary meteoroids smash into the planet’s four small inner moons. Galileo data showed that Jupiter’s outermost ring is actually two rings, one embedded within the other.

Galileo extensively investigated the geologic diversity of Jupiter’s four largest moons: Ganymede, Callisto, Io and Europa. Galileo found that Io’s extensive volcanic activity is 100 times greater than that found on Earth. The moon Europa, Galileo unveiled, could be hiding a salty ocean up to 100 kilometers (62 miles) deep underneath its frozen surface containing about twice as much water as all the Earth’s oceans. Data also showed Ganymede and Callisto may have a liquid-saltwater layer. The biggest discovery surrounding Ganymede was the presence of a magnetic field. No other moon of any planet is known to have one.

The prime mission ended six years ago, after two years of orbiting Jupiter. NASA extended the mission three times to continue taking advantage of Galileo’s unique capabilities for accomplishing valuable science. The mission was possible because it drew its power from two long-lasting radioisotope thermoelectric generators provided by the Department of Energy.

“The mission was a testimonial to the persistence of NASA even through tremendous challenges. It was a phenomenal mission,” said Sean O’Keefe, NASA administrator.

Original Source: NASA/JPL News Release

Early Supernovae Seeded the Universe With Elements

Image source: CfA

According to cosmologists, the early Universe only had a mixture of hydrogen, helium and other lighter elements, but none of the heaver elements required for life – like carbon. From the original gasses, giant stars formed – some were 200 times larger than our Sun – lived for a brief time, often just a few million years. These giant stars converted up to 50% of their material into heaver elements, mostly iron, before exploding violently as supernovae. The James Webb telescope, due for launch after 2011 will be so sensitive it should be able to look back to watch these supernovae happening.

The early universe was a barren wasteland of hydrogen, helium, and a touch of lithium, containing none of the elements necessary for life as we know it. From those primordial gases were born giant stars 200 times as massive as the Sun, burning their fuel at such a prodigious rate that they lived for only about 3 million years before exploding. Those explosions spewed elements like carbon, oxygen and iron into the void at tremendous speeds. New simulations by astrophysicists Volker Bromm (Harvard-Smithsonian Center for Astrophysics), Naoki Yoshida (National Astronomical Observatory of Japan) and Lars Hernquist (CfA) show that the first, “greatest generation” of stars spread incredible amounts of such heavy elements across thousands of light-years of space, thereby seeding the cosmos with the stuff of life.

This research is posted online at and will be published in an upcoming issue of The Astrophysical Journal Letters.

“We were surprised by how violent the first supernova explosions were,” says Bromm. “A universe that was in a pristine state of tranquility was rapidly and irreversibly transformed by a colossal input of energy and heavy elements, setting the stage for the long cosmic evolution that eventually led to life and intelligent beings like us.”

Approximately 200 million years after the Big Bang, the universe underwent a dramatic burst of star formation. Those first stars were massive and fast-burning, quickly fusing their hydrogen fuel into heavier elements like carbon and oxygen. Nearing the end of their lives, desperate for energy, those stars burned carbon and oxygen to form heavier and heavier elements until reaching the end of the line with iron. Since iron cannot be fused to create energy, the first stars then exploded as supernovae, blasting the elements that they had formed into space.

Each of those first giant stars converted about half of its mass into heavy elements, much of it iron. As a result, each supernova hurled up to 100 solar masses of iron into the interstellar medium. The death throes of each star added to the interstellar bounty. Hence, by the remarkably young age of 275 million years, the universe was substantially seeded with metals.

That seeding process was aided by the structure of the infant universe, where small protogalaxies less than one-millionth the mass of the Milky Way crammed together like people on a crowded subway car. The small sizes of and distances between those protogalaxies allowed an individual supernova to rapidly seed a significant volume of space.

Supercomputer simulations by Bromm, Yoshida, and Hernquist showed that the most energetic supernova explosions sent out shock waves that flung heavy elements up to 3,000 light-years away. Those shock waves swept huge amounts of gas into intergalactic space, leaving behind hot “bubbles,” and triggered new rounds of star formation.

Supernova expert Robert Kirshner (CfA) says, “Today this is a fascinating theory, based on our best understanding of how the first stars worked. In a few years, when we build the James Webb Space Telescope, the successor to the Hubble Space Telescope, we should be able to see these first supernovae and test Volker’s ideas. Stay tuned!”

Lars Hernquist notes that the second generation of stars contained heavy elements from the first generation – seeds from which rocky planets like Earth could grow. “Without that first, ‘greatest generation’ of stars, our world would not exist.”

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Original Source: CfA News Release