Newly released Hubble Space Telescope images of a vast debris disk encircling the
nearby star Fomalhaut, and of a mysterious planet circling it, may provide forensic
evidence of a titanic planetary disruption in the system. Astronomers are surprised
to find that the debris belt is wider than previously known, spanning a gulf of space
from 14 billion miles to nearly 20 billion miles from the star. Even more surprisingly,
the latest Hubble images have allowed a team of astronomers to calculate that the
planet follows an unusual elliptical orbit that carries it on a potentially destructive
path through the vast dust ring.
The planet, called Fomalhaut b, swings as close to its star as 4.6
billion miles, and the
outermost point of its orbit is 27 billion miles away from the star. The
orbit was re-calculated from the newest Hubble observation made in
2012. The Fomalhaut team
led by Paul Kalas (University of California, Berkeley) considers this
circumstantial
evidence that there may be other planet-like bodies in the system that
gravitationally disrupted Fomalhaut b to place it in such a highly
eccentric orbit. His
team is presenting their finding today at the 221st meeting of the
American
Astronomical Society in Long Beach, Calif.
The diagram compares the planets of the inner solar system to Kepler-62, a five-planet system about 1,200 light-years from Earth in the constellation Lyra. The five planets of Kepler-62 orbit a star classified as a K2 dwarf, measuring just two thirds the size of the sun and only one fifth as bright. At seven billion years old, the star is somewhat older than the sun. Much like our solar system, Kepler-62 is home to two habitable zone worlds, Kepler-62f and Kepler-62e. Kepler-62f orbits every 267 days and is only 40 percent larger than Earth, making it the smallest exoplanet known in the habitable zone of another star. The other habitable zone planet, Kepler-62e, orbits every 122 days and is roughly 60 percent larger than Earth. The size of Kepler-62f is known, but its mass and composition are not. However, based on previous exoplanet discoveries of similar size that are rocky, scientists are able to determine its mass by association. The two habitable zone worlds orbiting Kepler-62 have three interior companions, two larger than the size of Earth and one about the size of Mars. Kepler-62b, Kepler-62c and Kepler-62d, orbit every five, 12, and 18 days, respectively, making them very hot and inhospitable for life as we know it. The artistic concepts of the Kepler-62 planets are the result of scientists and artists collaborating to help imagine the appearance of these distant worlds. The Kepler space telescope, which simultaneously and continuously measures the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun. Image credit: NASA Ames/JPL-Caltech Mission: Kepler
GJ 504b orbits at least 44 Earth-Sun distances from
its host star, similar to Pluto's average distance from the Sun. The
light from the host star has been suppressed in this image, revealing a
tiny blue-white companion in the upper right corner. Click on the image
to see two side-by-side observations of the speck which distinguish it
from background noise.
One year ago tonight, I asked my Dad to take me to Space Center Houston to watch the Mars landing. I know, it sounds like a 10 year old kid asking. But the excitement was enough to make you feel like a kid again.
It was a last minute idea. I had not planned on going. The landing was scheduled to happen after midnight. I could have stayed home and watched the coverage on NASA TV. But I wanted to be there, to experience the excitement of the mission with other people.
The landing was labeled "Curiosity's 7 minutes of Terror!". From the top of the Martian atmosphere to its landing zone in Gale Crater, would take 7 minutes. For Curiosity to sent a signal to Earth takes 14 minutes. So by the time we would hear that Curiosity had entered the atmosphere, it would have already landed or crashed. I will let these guys explain it: http://www.youtube.com/watch?v=Ki_Af_o9Q9s Scary right?
My Dad and I arrived shortly after 10pm. There was already a good crowd. Admission was free. There were Astronauts signing autographs, games for the kids to play, things to build, plus free access to all the cool space artifacts there. After looking around we decided to take a seat in the cafe area where the main activities were going on. They had two big screens and in between them a podium where Astronauts and scientists were talking about mars science.
Finally the moment came. Curiosity entered the Martian atmosphere. The 7 minute countdown had begun. On one of the screens the Live Feed from NASA TV was on. The other screen had a simulation graphically showing the landing. As you will see in the video below, we were sitting in front of the screen showing the simulation. The entry proceeded normally. The folks at JPL were reading off the data as it came in. The crowd was mostly silent during the entry, occasionally cheering as some of the major events went by. Then the moment of truth came. The Skycrane was deployed! Some applause broke out when the simulation showed touchdown. But it was running a few seconds ahead of the live data. Finally the words everyone was waiting for "Touchdown Confirmed!". Cheering and clapping broke out in the crowd. On the screen we could see the Curiosity team jumping for joy. Minutes later the first picture was beamed back to Earth.
The next day the Houston Chronicle posted a photo from the event. After carefully scanning all the faces in the crowd, I was able to spot me and my Dad!
Photo Courtesy of the Houston Chronicle
The excitement from that night is still with me. When i watch the video again I feel like I am there all over again. I can't believe its already been 1 year.
Congratulations to the Curiosity team for 1 Year on Mars!
Researchers using data from NASA's Kepler space telescope have shown that migrating planets stop their inward journey before reaching their stars, as illustrated in this artist's concept. Jupiter-like planets, called "hot Jupiters" are known to migrate from their star's frigid outer reaches in toward the star and its blistering heat. Dozens of hot Jupiters have been discovered orbiting closely to their stars, whipping around in just days.
Until now, it was not clear whether these massive planets remain in stable orbits close to their stars or keep marching in closer and closer until they are ultimately consumed. The new work not only demonstrates that the planets stop their migration inward, but also shows how. The tidal, or gravitational, forces acting to circularize the orbits of the planets cause them to cease their inbound travels once they have hit the stable orbits.
This graphic depicts HD 189733b, the first exoplanet caught passing in front of its parent star in X-rays. As described in our press release , NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM Newton Observatory have been used to observe a dip in X-ray intensity as HD 189733b transits its parent star.
The main figure is an artist’s impression showing the HD 189733 system, containing a Sun-like star orbited by HD 189733b, an exoplanet about the size of Jupiter. This “hot Jupiter” is over 30 times closer to its star than Earth is to the Sun and goes around the star once every 2.2 days, as determined from previous observations. Also in the illustration is a faint red companion star, which was detected for the first time in X-rays with these observations. This star orbits the main star about once every 3,200 years.
The inset contains the Chandra image of HD 189733. The source in the middle is the main star and the source in the lower right is the faint companion star. The source at the bottom of the image is a background object not contained in the HD 189733 system.
The exoplanet itself cannot be seen in the Chandra image, as the transits involve measuring small decreases in X-ray emission from the main star. The authors estimate that the percentage decrease in X-ray light during the transits is about three times greater than the corresponding decrease in optical light. This tells them that the region blocking X-rays from the star is substantially larger than the region blocking optical light from the star, helping to determine the size of the planet's atmosphere. The extended atmosphere implied by these results is shown by the light blue color around the planet. Recent observations of HD 189733b with the Hubble Space Telescope have confirmed that the lower atmosphere of the planet has a deep blue color, due to the preferential scattering of blue light by silicate particles in its atmosphere.
For about a decade astronomers have known that ultraviolet and X-ray radiation from the main star in HD 189733 are evaporating the atmosphere of its closely orbiting planet over time. The authors of the new study estimate that HD 189733b is losing between 100 million and 600 million kilograms per second. This rate is about 25% to 65% higher than it would be if the planet's atmosphere were not extended.
At a distance of just 63 light years, HD 189733b is the closest hot Jupiter to Earth, which makes it a prime target for astronomers who want to learn more about this type of exoplanet and the atmosphere around it.
Chandra was used to make observations of six transits by HD 189733b and the team also used archival data from XMM-Newton for one transit. These results are available online and will appear in the August 10th issue of The Astrophysical Journal.
