Posted on by Fraser Cain

I’m Looking for More Writers

As you’ve probably noticed, I’ve got a solid group of freelance writers working with me to help update Universe Today. There are a lot of stories that we just don’t have time to cover, though, so I’m looking to get more writers involved. If you’re a freelance science journalist, or want to become one and you have writing experience, please drop me an email with some of your writing samples. I’m especially looking for people with experience in space exploration news (NASA, Hubble, etc) as opposed to astronomy news (we’ve got lots of people for that).

And yes, I actually pay for articles I publish (thanks to all your donations).

Thanks!

Fraser Cain
Publisher
Universe Today

Posted on by Mark Mortimer

Book Review: Space Tourism – Adventures in Earth Orbit and Beyond

Space tourism seems as obtainable to us as the sun was to Icarus. We struggle to maintain and inhabit a man made structure in the safety of low Earth orbit. Yet, we read about hotels that will allow honeymooners to gaze at the sun setting every 90 minutes. This may be a bit of a stretch, but space tourism can solidly generate revenue for some entrepreneur. As Van Pelt notes, two people have already paid significant amounts, $20 million each, to visit space. Further, as the attraction would easily better any other on planet Earth, all that’s needed is a price low enough. With this, hundreds of people each year would spend their annual vacations in orbit. It is an extreme engineering challenge if there ever was one. Still, from Van Pelt’s perspective, it’s quite obtainable.

Through the book, Van Pelt discusses the technical issues of space flight and pleasant issues of leisure time in space. In a neutral, analytical view, he considers technical issues, starting with the history of space activities, the progressive development of launch vehicles, existing state of the art capabilities and the steps needed to enable the space tourism industry. Practicalities like radiation dosimetres, pressure suits to counter g forces, pre-flight training and group interactions also get attention. These and other technical details are faithfully extended from current or historically established technology. However, launcher reusability is favoured without much supporting justification. Also, some of the later discussion about warp drives, transporters and faster than light travel seem a little out of place and add an incredulous tone to an otherwise rational and even presentation.

Van Pelt has much more fun with the leisure time activities. Using a first person perspective, he places the reader on a three day vacation to an orbiting hotel. The novelty of training, safety lessons and equipment fit-out comes through like any tourist getting ready to embark on some adventurous voyage to the big unknown. Continual comparisons to today’s commercial aeroplane flights enhance the nearness of this opportunity. Further chapters on the launch, ascent and commencement of microgravity quickly distance this trip from any commercial flight. The prose really puts the reader’s feet in the shoes of the starry eyed guest. The descent and landing give the pleasant denouement that would leave the space flyer, and presumably the reader, earnestly desiring another flight. Van Pelt also forays into predicting voyage highlights by imagining sports, games, trysts, and dancing in the realm of microgravity. He ably amplifies how common activities can take on exhilarating dimensions in the confines of a space hotel or on distant surfaces such as the 1/6’th gravity of the moon. There certainly shouldn’t be any lack of fun should his views come to pass.

To aid the reader, the two aspects of the book, the technical and first person view, come in their own chapters. Each follows along logically from the predecessor. For example, first the technical chapter discusses launch vehicles. Then, the first person view places the reader in the eyes of a person as they are launched. Despite these two aspects, the prose remains complimentary, the technical part not being too dry nor the first person view being too qualitative.

As well, the imagination and optimism shown in this book makes for an enjoyable and quick read. Quotes from science fiction writers shows how reality keeps catching up to the earlier imagination of writers from many years ago. Sometimes the optimism gets a bit much though. Van Pelt would have us believe that only a few different decisions at various stages in the United States’ space program would have had people on Mars by now. Also, the discussions about travelling to Mars and further distant planets or stars again raise incredulity rather than support the perceived industry. To build credence and optimism, these parts of the book should have been balanced with more details on means and methods of constructing the infrastructure.

Reality keeps catching up with science fiction. Scientists labour in labs while engineers construct in the field in order to bring the future a little closer to today. However, even they will need to rest and recharge. Michel Van Pelt describes the perfect travel location for recharging in his book, Space Tourism and shows what we need to get there and what may happen once we arrive.

Read more reviews online or purchase a copy from Amazon.com.

Review by Mark Mortimer.

Posted on by Fraser Cain

Solar Astronomers Getting Better at Predicting Solar Wind

SOHO image of the Sun that shows magnetic fields (yellow lines) and the solar wind (red arrows). Image credit: NASA/ESA. Click to enlarge.
A layer deep in the solar atmosphere can be used to estimate the speed of the solar wind, a stream of electrified gas that constantly blows from the Sun. Estimating the speed of the solar wind will improve space weather forecasts, which will aid human exploration of the planets.

The solar wind flows from the Sun’s hot, thin, outer atmosphere, the “corona”. The researchers were surprised to discover that the structure of the Sun’s cooler, dense lower atmosphere, called the chromosphere, could be used to estimate the speed of the solar wind.

This was unexpected because the solar wind is a phenomenon of the corona, and the chromosphere is so deep — it’s the layer just above the Sun’s visible surface. “It’s like discovering that the source of the river Nile is another 500 miles inland,” said Dr. Scott McIntosh of the Southwest Research Institute, Boulder, Colo., lead author of a paper on this research published May 10 in the Astrophysical Journal.

The new work promises to increase the accuracy of space radiation forecasts. The Sun occasionally launches billion-ton blasts of electrified gas, called coronal mass ejections (CMEs), into space at millions of miles (kilometers) per hour. If a fast CME is plowing through slow solar wind, a shock builds up in front of the CME that accelerates the electrically charged solar wind particles. These fast particles can disrupt satellites and are hazardous to unprotected astronauts.

“Just as knowing more details about the atmosphere helps to predict the intensity of a hurricane, knowing the speed of the solar wind helps to determine the intensity of space radiation storms from CMEs,” said co-author Dr. Robert Leamon of L-3 Government Services at NASA’s Goddard Space Flight Center, Greenbelt, Md.

Like wind on Earth, the solar wind is gusty, ranging in speed from about 750,000 miles per hour (approximately 350 km/second) to 1.5 million miles per hour (700 km/second).

Since the solar wind is made up of electrically-charged particles, it responds to magnetic fields that permeate the solar atmosphere. Solar wind particles flow along invisible lines of magnetic force like cars on a highway. When the magnetic field lines bend straight out into space, as they do in “coronal hole” regions, the solar wind acts like cars on a drag strip, racing along at high speed. When the magnetic field lines bend sharply back to the solar surface, like the pattern of iron filings around a bar magnet, the solar wind acts like cars in city traffic and emerges relatively slowly. Scientists have known this for over thirty years and used it to give a crude estimate for the speed of the solar wind — either fast or slow.

In the new work, the team has tied the speed of the solar wind as it blows past Earth to variations deeper in the solar atmosphere than had previously been detected (or even expected). By measuring the time taken for a sound wave to travel between two heights in the chromosphere, they were able to determine that the chromosphere is effectively “stretched thin” below coronal holes with their open magnetic fields, but compressed below magnetically closed regions.

The team used the observation to derive a continuous range of solar wind speeds from the structure of the chromosphere. The wider the chromospheric layer is, the more it is being allowed to expand by open magnetic fields and the faster the solar wind will blow. This new method is more precise than the old “fast or slow” estimate.

NASA’s Transition Region and Coronal Explorer (TRACE) spacecraft was used to measure the speed of sound waves in the chromosphere, and NASA’s Advanced Composition Explorer (ACE) spacecraft was used to take measurements of the solar wind speed as it blew by the Earth. Comparing the data from the two spacecraft gave the connection.

“Prior to this discovery, we could only determine solar wind speed from spacecraft that were roughly in line between the Earth and the Sun, like ACE, WIND, and the Solar and Heliospheric Observatory. This spacecraft fleet was placed along the Earth-Sun line because we need to know about the space weather coming our way. However, compared to the size of our solar system, this is a very narrow range; it’s like looking through a soda straw. With this discovery, we can use TRACE to build up images that can predict the solar wind speed throughout half the solar system,” said Dr. Joe Gurman, a solar researcher at NASA Goddard.

Original Source: SWRI News Release

Posted on by Fraser Cain

Enceladus Above Saturn’s Rings

Saturn’s icy moon Enceladus above the rings. Image credit: NASA/JPL/SSI. Click to enlarge.
Saturn’s icy moon Enceladus hovers above Saturn’s exquisite rings in this color view from Cassini. The rings, made of nearly pure water ice, have also become somewhat contaminated by meteoritic dust during their history, which may span several hundred million years. Enceladus shares the rings’ nearly pure water ice composition, but appears to have eluded dust contamination through resurfacing processes that scientists are still trying to understand. Enceladus is 505 kilometers (314 miles) across.

Dust affects the rings’ color, while differences in brightness are attributable to varying particle sizes and concentrations.

The images for this natural color view were taken with the Cassini spacecraft narrow-angle camera on April 5, 2005, at a distance of approximately 2.2 million kilometers (1.4 million miles) from Saturn through red, green and blue spectral filters. The image scale is 13 kilometers (8 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . For additional images visit the Cassini imaging team homepage http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Weather Satellite Launches After Several Delays

Artist interpretation of the NOAA-18 satellite in orbit. Image credit: NOAA. Click to enlarge.
NASA successfully launched a new environmental satellite today for the National Oceanic and Atmospheric Administration (NOAA). It will improve weather forecasting and monitor environmental events around the world.

The NOAA-18 (N) spacecraft lifted off at 6:22 a.m. EDT from Vandenberg Air Force Base, Calif., on a Boeing Delta II 7320-10 expendable launch vehicle. Approximately 65 minutes later, the spacecraft separated from the Delta II second stage.

“The satellite is in orbit and all indications are that we have a healthy spacecraft,” said Karen Halterman, the NASA Polar-orbiting Operational Environmental Satellites (POES) Project Manager, Goddard Space Flight Center (GSFC), Greenbelt, Md. “NASA is proud of our partnership with NOAA in continuing this vital environmental mission,” she added.

Flight controllers tracked the launch vehicle’s progress using real-time telemetry data relayed through NASA’s Tracking and Date Relay Satellite System (TDRSS) starting about five minutes after launch. Approximately 26 minutes after launch, controllers acquired the spacecraft through the McMurdo Sound ground station, Antarctica, while the spacecraft was still attached to the Delta II. Spacecraft separation was monitored by the TDRSS.

The solar array boom and antennas were successfully deployed, and the spacecraft was placed in a near-perfect orbit. The satellite was acquired by the NOAA Fairbanks Station, Alaska, 86 minutes after launch and deployments, and a nominal spacecraft power system was confirmed. NOAA-N was renamed NOAA-18 after achieving orbit.

NOAA-18 will collect data about the Earth’s surface and atmosphere. The data are input to NOAA’s long-range climate and seasonal outlooks, including forecasts for El Nino and La Nina. NOAA-18 is the fourth in a series of five Polar-orbiting Operational Environmental Satellites with instruments that provide improved imaging and sounding capabilities.

NOAA-18 has instruments used in the international Search and Rescue Satellite-Aided Tracking System, called COSPAS-SARSAT, which was established in 1982. NOAA polar-orbiting satellites detect emergency beacon distress signals and relay their location to ground stations, so rescue can be dispatched. SARSAT is credited with saving approximately 5,000 lives in the U.S. and more than 18,000 worldwide.

Twenty-one days after spacecraft launch, NASA will transfer operational control of NOAA-18 to NOAA. NASA’s comprehensive on-orbit verification period is expected to last approximately 45 days.

NOAA manages the POES program and establishes requirements, provides all funding and distributes environmental satellite data for the United States. GSFC procures and manages the development and launch of the satellites for NOAA on a cost-reimbursable basis.

NASA’s Kennedy Space Center, Fla., was responsible for the countdown management and launch of the Delta II, which was provided by Boeing Expendable Launch Systems, Huntington Beach, Calif.

Original Source: NASA News Release

Posted on by Fraser Cain

NASA Competition to Get Air from Lunar Soil

Astronauts in a lunar base will need a lot of air. Image credit: NASA. Click to enlarge.
NASA, in collaboration with the Florida Space Research Institute (FSRI), today announced a new Centennial Challenges prize competition.

The MoonROx (Moon Regolith Oxygen) challenge will award $250,000 to the first team that can extract breathable oxygen from simulated lunar soil before the prize expires on June 1, 2008.

For the MoonROx challenge, teams must develop hardware within mass and power limits that can extract at least five kilograms of breathable oxygen from simulated lunar soil during an eight-hour period. The soil simulant, called JSC-1, is derived from volcanic ash. The oxygen production goals represent technologies that are beyond existing state-of-the-art.

NASA’s Centennial Challenges promotes technical innovation through a novel program of prize competitions. It is designed to tap the nation’s ingenuity to make revolutionary advances to support the Vision for Space Exploration and NASA goals.

“The use of resources on other worlds is a key element of the Vision for Space Exploration,” said NASA’s Associate Administrator for the Exploration Systems Mission Directorate, Craig Steidle. “This challenge will reach out to inventors who can help us achieve the Vision sooner,” he added.

“This is our third prize competition, and the Centennial Challenges program is getting more and more exciting with each new announcement. The innovations from this competition will help support long-duration, human and robotic exploration of the moon and other worlds,” said Brant Sponberg, NASA’s Centennial Challenges program manager.

“Oxygen extraction technologies will be critical for both robotic and human missions to the moon,” said FSRI Executive Director Sam Durrance. “Like other space-focused prize competitions, the MoonROx challenge will encourage a broad community of innovators to develop technologies that expand our capabilities,” he added.

The Centennial Challenges program is managed by NASA’s Exploration Systems Mission Directorate. FSRI is a state-wide center for space research. It was established by Florida’s governor and legislature in 1999.

For more information about Centennial Challenges on the Internet, visit: http://centennialchallenges.nasa.gov

For more information about NASA and agency programs on the Internet, visit: http://www.nasa.gov/home/index.html

For information about the Florida Space Research Institute on the Internet, visit: http://www.fsri.org

Original Source: NASA News Release

Posted on by Fraser Cain

Cosmic Rays Cause the Brightest Radio Flashes

Low-frequency radio sky at the time of a cosmic ray hit. Image credit: MPIFR. Click to enlarge.
Using the LOPES experiment, a prototype of the new high-tech radio telescope LOFAR to detect ultra-high energy cosmic ray particles, a group of astrophysicists, in collaboration of Max-Planck-Gesellschaft and Helmholtz-Gemeinschaft, has recorded the brightest and fastest radio blasts ever seen on the sky. The blasts, whose detection are reported in this week’s issue of the journal Nature, are dramatic flashes of radio light that appear more than 1000 times brighter than the sun and almost a million times faster than normal lightning. For a very short moment these flashes – which had gone largely unnoticed so far – become the brightest light on the sky with a diameter twice the size of the moon.

The experiment showed that the radio flashes are produced in the Earth atmosphere, caused by the impact of the most energetic particles produced in the cosmos. These particles are called ultra-high energy cosmic rays and their origin is an ongoing puzzle. The astrophysicists now hope that their finding will shed new light on the mystery of these particles.

The scientists used an array of radio antennas and the large array of particle detectors of the KASCADE-Grande experiment at Forschungszentrum Karlsruhe. They showed that whenever a very energetic cosmic particle hit the Earth atmosphere a corresponding radio pulse was recorded from the direction of the incoming particle. Using imaging techniques from radio astronomy the group even produced digital film sequences of these events, yielding the fastest movies ever produced in radio astronomy. The particle detectors provided them with basic information about the incoming cosmic rays.

The researchers were able to show that the strength of the emitted radio signal was a direct measure of the cosmic ray energy. “It is amazing that with simple FM radio antennas we can measure the energy of particles coming from the cosmos” says Prof. Heino Falcke from the Netherlands Foundation for Research in Astronomy (ASTRON) who is the spokesperson of the LOPES collaboration. “If we had sensitive radio eyes, we would see the sky sparkle with radio flashes”, he adds.

The scientists used pairs of antennas similar to those used in ordinary FM radio receivers. “The main difference to normal radios is the digital electronics and the broad-band receivers, which allow us to listen to many frequencies at once”, explains Dipl. Phys. Andreas Horneffer, a graduate student of the University of Bonn and the International Max-Planck Research School (IMPRS), who installed the antennas as part of his PhD project.

In principle some of the detected radio flashes are in fact strong enough to wipe out conventional radio or TV reception for a short time. To demonstrate this effect the group has converted their radio reception of a cosmic ray event into a sound track (see below). However, since the flashes only last for some 20-30 nanoseconds and bright signals happen only once a day, they would be hardly recognisable in everyday life.

The experiment also showed that the radio emission varied in strength relative to the orientation of the Earth magnetic field. This and other results verified basic predictions that had been made in theoretical calculations earlier by Prof. Falcke and his former PhD student Tim Huege, as well as by calculations of Prof. Peter Gorham from the University of Hawaii.

Cosmic ray particles constantly bombard the earth causing little explosions of elementary particles which form a beam of matter and anti-matter particles rushing through the atmosphere. The lightest charged particles, electrons and positrons, in this beam will be deflected by the geomagnetic field of the Earth which causes them to emit radio emission. This type of radiation is well known from particle accelerators on Earth and is called synchrotron radiation. In analogy, the astrophysicists now speak of “geosynchrotron” radiation due to the interaction with the Earth magnetic field.

The radio flashes were detected by the LOPES antennas installed at the KASCADE-Grande cosmic ray air shower experiment at Forschungszentrum Karlsruhe, Germany. KASCADE-Grande is a leading experiment for measuring cosmic rays. “This shows the strength of having a major astroparticle physics experiment directly in our neighbourhood – this gave us the flexibility to also explore unusual ideas as this one” says Dr. Andreas Haungs, spokesperson of KASCADE-Grande.

The radio telescope LOPES (LOFAR Prototype Experimental Station) uses prototype antennas of the largest radio telescope of the world, LOFAR, to be built after 2006 in the Netherlands and parts of Germany. LOFAR has a radical new design, combining a multitude of cheap low-frequency antennas which collect the radio signals from the entire sky at once. Connected by high-speed internet a supercomputer then has the ability to detect unusual signals and make images of interesting regions on the sky without moving any mechanical parts. “LOPES achieved the first major scientific results of the LOFAR project already in the development phase. This makes us confident that LOFAR will indeed be as revolutionary as we had hoped it will be.” explains Prof. Harvey Butcher, director of the Netherlands Foundation for Research in Astronomy (ASTRON) in Dwingeloo, The Netherlands, where LOFAR is currently being developed.

“This is indeed an unusual combination, where nuclear physicists and radio astronomers work together to create a unique and highly original astroparticle physics experiment”, states Dr. Anton Zensus, director at the Max-Planck-Institut f?r Radioastronomie (MPIfR) in Bonn. “It paves the way for new detection mechanisms in particle physics as well as demonstrating the breathtaking capabilities of the next generation telescopes such as LOFAR and later the Square Kilometer Array (SKA). Suddenly major international experiments in different research areas come together”

As a next step the astrophysicists want to use the upcoming LOFAR array in the Netherlands and Germany for radio astronomy and cosmic ray research. Test are under way to integrate radio antenna into the Pierre Auger Observatory for cosmic rays in Argentina and possibly later in the second Auger Observatory in the Northern hemisphere. “This may be a major breakthrough in detection technology. We hope to use this novel technique for detecting and understanding the nature of the highest energy cosmic rays and also to detect ultra-high energy neutrinos from the cosmos”, says Prof. Johannes Bl?mer, Astroparticle Physics programme director of the Helmholtz Association and at Forschungszentrum Karlsruhe.

The detection has been confirmed in part by a French group using the large radio telescope of the Paris observatory at Nan?ay. Historically, work on radio emission from cosmic rays was first done in the late 1960ies with the first claims of detections. However, no useful information could be extracted with the technology of these days, and the work ceased quickly. The main shortcomings were the lack of imaging capabilities (now implemented by software), the low time resolution, and the lack of a well-calibrated particle detector array. All of this has been overcome with the LOPES experiment.

Original Source: MPI News Release

Posted on by Fraser Cain

Actual Photo of Mars Odyssey in Orbit

Mars Global Surveyor took this image of Mars Odyssey while both spacecraft were in orbit around Mars. Image credit: NASA/JPL. Click to enlarge.
Photographs from NASA’s Mars Global Surveyor spacecraft released today are the first pictures ever taken of a spacecraft orbiting a foreign planet by another spacecraft orbiting that planet.

The new images of the European Space Agency’s Mars Express and NASA’s Mars Odyssey are available on the Internet from NASA at http://www.nasa.gov/vision/universe/solarsystem/mgs-images.html and from Malin Space Science Systems, the San Diego company that built and operates the camera, at http://www.msss.com/mars_images/moc/2005/05/19/index.html.

Mars Global Surveyor has been orbiting Mars since 1997, Mars Odyssey since 2001. Both are managed for NASA by the Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif. Mars Express has been in orbit since late 2003.

Mars Express was passing about 155 miles away when the Mars Orbiter Camera on Mars Global Surveyor photographed it on April 20. The next day, the camera caught Mars Odyssey passing 56 to 84 miles away.

All three spacecraft are moving at almost 7,000 miles per hour, and at 62 miles distance the field-of-view of the Mars Orbiter Camera is only 830 yards across. If timing had been off by only a few seconds, the images would have been blank.

The images were obtained by the Mars Global Surveyor operations teams at Lockheed Martin Space Systems, Denver; JPL and Malin Space Science Systems.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Dark Energy Could be a Breakdown of Einstein’s Theory

Hubble deep field view. Image credit: Hubble. Click to enlarge.
Cosmologists from Princeton University announced a new method to understand why the expansion of the universe is speeding up. The proposed technique will be able to determine if the cosmic acceleration is due to a yet unknown form of Dark Energy in the universe or if it is a signature of a breakdown of Einstein’s theory of General Relativity at very large scales of the universe. The result is being presented today by the principal investigator, Dr. Mustapha Ishak-Boushaki, a research associate at Princeton University in New Jersey, to the Canadian Astronomical Society meeting in Montreal, QC.

“The accelerating expansion of the universe constitutes one of the most intriguing and challenging problems in astrophysics. Moreover, it is related to problems in many other fields of physics. Our research work is focused on constraining different possible causes of this acceleration.” says Dr. Ishak-Boushaki.

During the last 8 years, several independent astronomical observations have demonstrated that the expansion of the universe has entered a phase of acceleration. The discovery of this acceleration came as a surprise to astrophysicists who were expecting to measure a slowing down of the expansion caused by the gravitational attraction of ordinary matter in the universe.

In order to explain the cosmic acceleration, theoretical cosmologists introduced the notion of a new energy component that would constitute two thirds of the entire energy density of the universe and that is gravitationally repulsive rather than attractive. This component has been termed Dark Energy.

Is Dark Energy real? “We don’t know,” comments Professor David Spergel from Princeton. “It could be a whole new form of energy or the observational signature of the failure of Einstein’s theory of General Relativity. Either way, its existence will have profound impact on our understanding of space and time. Our goal is to be able to distinguish the two cases.”

The simplest case of Dark Energy is the cosmological constant that Einstein introduced 80 years ago in order to reconcile his theory of General Relativity with his prejudice that the universe is static. He had to withdraw the cosmological constant a few years later when the expansion of the universe was discovered. The discovery of the cosmic acceleration has revived the debate about the cosmological constant in a new context.

Another fundamentally different possibility is that the cosmic acceleration is a signature of a new theory of gravity that enters at very large scales of the universe rather than the product of Dark Energy. Some of the recently proposed modified gravity models are inspired by Superstring theory and extra dimensional physics.

Could we distinguish between these two possibilities? The proposed procedure shows that the answer is yes. The general idea is as follows. If the acceleration is due to Dark Energy then the expansion history of the universe should be consistent with the rate at which clusters of galaxies grow. Deviations from this consistency would be a signature of the breakdown of General Relativity at very large scales of the universe. The procedure proposed implements this idea by comparing the constraints obtained on Dark Energy from different cosmological probes and allows one to clearly identify any inconsistencies.

As an example, a universe described by a 5-dimensional modified gravity theory was considered in this study and it was shown that the procedure can identify the signature of this theory. Importantly, it was shown that future astronomical experiments can distinguish between modified gravity theories and Dark Energy models.

The research work on the results presented was led by Dr. Mustapha Ishak-Boushaki in collaboration with Professor David Spergel, both from the Department of Astrophysical Sciences at Princeton University, and Amol Upadhye, a graduate student at the Physics Department at Princeton University.

Original Source: Princeton News Release

Posted on by Fraser Cain

Planet Forces its Star’s Rotation

ESO image of a completely different star, 2M1207, and its planet. Image credit: ESO. Click to enlarge.
Canadian astronomers using the MOST space telescope have observed a remarkable planetary system where a giant close-in planet is forcing its parent star to rotate in lock-step with the planet’s orbit. “This is truly a stellar story of `tail wags dog’,” according to Dr. Jaymie Matthews of the University of British Columbia, leader of the Canadian Space Agency’s MOST space telescope mission, in an announcement about the exoplanetary system tau Bootis made at the annual meeting of the Canadian Astronomical Society in Montreal today.

“The interactions between the star and the giant planet in the tau Bootis system are unlike anything astronomers have seen before,” elaborates Dr. Matthews. “And they would be undetectable by any instrument on Earth or in space other than MOST.”

The MOST (Microvariability & Oscillations of STars) satellite has revealed that the star tau Bootis is undergoing subtle variations in its light output that are in synch with the orbit of the planet – unimaginatively designated tau Bootis b – in a tight orbit around it. The best explanation is that the planet’s gravity has forced the outer envelope of the star to rotate so it always keeps the same face to the planet – despite the fact that the planet is probably under 1% of the star’s mass.

“It’s no surprise when a star or planet gravitationally forces its smaller companion to spin according to its orbital rhythm, like the Moon always keeping the same face to the Earth,” Dr. Matthews explains. “But for a planet to force a star to do this is very unusual.” In all likelihood, only the surface layers of gas in the star have succumbed to the planet’s influence, just as in the Earth-Moon system, where the Moon has succeeded in causing a bulge in the thin layer of water on the Earth’s surface which results in the ocean tides, but has not forced the massive solid Earth underneath to rotate in step.

The only reason why the planet can lead even part of the star in the tau Bootis system is because it orbits so closely – only 1/20th of the Earth-Sun distance – and because it’s quite big as planets go – at least 4 times the mass of Jupiter, the largest planet in our own Solar System. The planet was discovered in 1997 by American astronomers Paul Butler, Geoff Marcy and colleagues based on the wobbling motions induced in the star by the 3.3-day orbit of an unseen companion. With such a small orbit, you might expect other complicated interactions between the star and planet, and MOST has observed evidence for these as well. There are indirect indications of starspots, tidal distortion, and even magnetic activity on the surface of tau Boo a.

Last year, another team of Canadian scientists, led by Evgenya Shkolnik (an alumna of UBC now at the University of Hawaii) and Gordon Walker (an exoplanet pioneer and MOST Science Team member at UBC), presented evidence in a system similar to tau Boo, HD179949, for a planet heating up the gas in its parent star, which is also behaviour never seen before. This would probably be caused by the entanglement of a magnetic field of the planet with the star’s field. “We may be witnessing another example of this in tau Bootis,” notes Dr. Walker. “The nature of the light variations is different for each of the nine exoplanet orbits monitored by MOST in 2004 and 2005. The explanation for all the variability will have to include intrinsic stellar effects, like rotation, and planet-induced effects, like heating caused by tides and magnetic fields – a complex model, to be sure.”

The theories of the origins and evolution of planetary systems were shaken up a decade ago with the discovery of the first of these giant close-in exoplanets (dubbed “hot Jupiters”) around the Sun-like star, 51 Pegasi. The planet in the tau Bootis system is more massive and closer to its star than the one in 51 Pegasi, and represents a remote laboratory for planetary scientists to test new theories about planet formation that will eventually be applied to our own Solar System. The details revealed by MOST have already excited theorists, and certainly excited the observers on the MOST team. Dr. Rainer Kuschnig, MOST Instrument Scientist (UBC) can barely contain his enthusiasm: “It’s tremendous fun to watch the data on this system come in from the satellite and see something new every day. It’s so cool!”

MOST (Microvariability & Oscillations of STars) is a Canadian Space Agency mission. Dynacon Inc. of Mississauga, Ontario, is the prime contractor for the satellite and its operation, with the University of Toronto Institute for Aerospace Studies (UTIAS) as a major subcontractor. The University of British Columbia (UBC) is the main contractor for the instrument and scientific operations of the MOST mission. MOST is tracked and operated through a global network of ground stations located at UTIAS, UBC and the University of Vienna.

Animations of eta Boo and tau Boo are available at:

http://www.astro.umontreal.ca/~casca/PR/etaBoo2.wmv
http://www.astro.umontreal.ca/~casca/PR/tauBootis3.wmv

Original Source: MOST News Release