August 20th Radio Show Online: More on Extra-Solar Planets

Available here is the August 20th episode of this radio show. In addition to usual Astronomy news and notes, I continue discussing the latest results concerning extrasolar planets - specifically measurements of their physical properties. A more detailed description will come soon, but in the meantime, hope you enjoy!

Description of August 13th Radio Show: Planet Formation and Extrasolar Planets

Below is the detailed description of August 13th edition of this radio show, already available here. On this program, I talked about:

• News: No, Phoenix Mars Lander has not detected life of Mars, even though one of the instruments on the Phoenix Mars Lander did detect a type of salt called perchlorate - a fuel source for some micro-organisms on Earth (link); ice in Martian soil may be preventing soil samples from entering the instruments on Phoenix Mars Lander; Cassini prepares to fly within 30 miles of geysers erupting on the surface of Saturn's moon Enceladus (link), initial data already received; Hubble Space Telescope celebrates its 100,000th orbit around the Earth by taking this image of a star forming region near star cluster NGC 2074 (link); instruments on the Hubble Space Telescope slated for repair during final servicing mission to occur in October (link) - astronauts interviewed August 11th; new book on how the Hubble Space Telescope got built recently published - "The Universe in a Mirror" by Robert Zimmerman; Interstellar Boundary Explorer mission undergoing testing of science instruments prior to its October 5th launch; bizarre object discovered by Dutch school teacher Hanny van Arkel in archived images of the night sky maintained by http://www.galaxyzoo.org (link); David Dunlap Observatory in Toronto sold to a developer; NASA's Aerospace Safety Advisory Panel releases annual report, available here; NASA readjusts time table of Constellation Program - the successor to the space shuttle; NASA awards prized at General Aviation Technology Challenge (link); NASA says farewell to this year's group of high school and college aged INSPIRE interns (link to INSPIRE program); NASA awards space radiobiology grants (link); Arizona students talked with astronaut Greg Chamitoff on International Space Station on August 15th.
• "Wednesday Morning Astronomers": An astronomer's opinion on the Astronomy content in Gregg Easterbrook's weekly column on ESPN's Page 2, available here - yes, it is extremely cheesy that Doritos broadcast an ad towards a nearby star, and I also hope they aren't offended by it. I also find it extremely disturbing that a NASA press release concerning a Spitzer observation of a star similar to that of the Sun was quashed for being "alarmist."
• Calendar of upcoming astronomical and science events in the greater Poughkeepsie/New York City area.
• Planet Formation: As explained previously no this program by Dr. Aki Roberge, planets are believed to form in the gas and dust disks left behind after a star forms. The starlight from the central star has a large effect on the gas and dust in this disk, possibly driving larger icy bodies out to the solar system before gas drag causes to circulate inwards. This can lead to the formation of organic molecules and water in this "proto-planetary" disk, as was recently observed (article). Planets in this disk are expected to grow from dust grains colliding and sticking together to form pebbles, which in turn stick together to from proto-planets, which then form planets. These dust grains and pebbles scatter the light from the central star, and this scattered light has been observed from the proto-planetary disk around KH 15B binary star system. As the planet grows, it carves out a gap in the disk detectable in radio observations of the gas and dust. This has been seen around a very young star, <100000 years old, HL Tau - implying that planets form very rapidly (link), as well as around older star AB Aurigae (link).
• Extra-Solar Planets: Currently, there are three major observational techniques to detect planets around other stars - the radial velocity method, which detects the motion of the central star caused by the gravitational pull of the planet, the transit method - which detects a decrease in the light from the central star caused by the planet passing between the Earth and the star, and microlensing technique - where the gravitational field of the planet bends the light from the star such that its brightness on Earth increases very quickly. All of these techniques require monitoring the properties of many stars at once. An upcoming project to do this using the radial velocity method is MARVELS. The radial velocity method requires precision measurements of the star's spectrum since the planet's signature is a periodic change in the central frequency of spectral lines. This requires very good calibration of the spectrometer, which might be easier and 100x more sensitive thanks to a new laser standard (link). There are many transiting planet searches being conducted on the ground and from space. One such satellite, the COROT mission, has discovered a planet orbiting a Sun-like star, though at an orbit very different from the Earth's (link). NASA has also directed a spacecraft which orbits comets to look for transiting planets in it's spare time, the EPOXI mission (link). A new detector possibly capable of detecting the transit from an Earth-size planet around another star is being developed in the UK called "RISE" (link). The microlensing technique has recently been used to detect a planet just three times the size of the Earth, the smallest extra-solar planet yet. SuperWASP, a transiting planet survey, has recently detecting 10 extra-solar planets with different sizes and orbits (link). A rocky planet has been inferred around another star due to its gravitational effect on a previous detected planet in this "solar system" - it has since been detected using the radial velocity method (link), as have three other Earth-like planets (link). Small planets have also been detected around small stars like brown dwarfs (link). It has been speculated the nearest star to the Sun, Alpha Centauri, might have Earth-like planets around it (link). Last, but not least, even though planetary nebulae have nothing to do with planets, a planet has been discovered inside one (link).

Sorry for the delay in posting this. Thank you very much for listening, hope you enjoyed it, and any and all feedback will be appreciated.

GLAST Press Conference

NASA's newest astronomical satellite, the currently named Gamma-ray Large Area Space Telescope (GLAST), has been up in space since June 11. It has finished it's engineering check-up and has now started taking science data. Tomorrow, NASA will hold a press conference at 1 PM ET, which will be stream live here. For more info on GLAST, check out this information page for media members, as well as my interviews with Dr. Julie McEnery, Dr. Dave Thompson, and Dr. Charles Meegan on the different instruments and scientific goals of GLAST. Last, but definitely not least, Dr. Steve Ritz - one of the top astronomers on GLAST - maintains a blog available here with the latest updates. Enjoy!

August 13th Radio Show: Planet Formation and Extrasolar Planets

Now available here is the August 13th episode of this radio show. In addition to the usual Astronomy news and notes, and the return of "Wednesday Morning Astronomer", I talked about the latest news and results concerning our understanding of how planets form and the properties of planets detected orbiting other stars. I hope to put a more detailed description online, soon. I promise.

Description of August 6th Radio Show: Star Formation and Brown Dwarfs

I know I already posted the August 6th radio show here, but below is a detailed description of what I actually talked about:

• Mars Phoenix Lander: The Thermal and Evolved Gas-Analyzer (TEGA) instrument detects water in sub-surface Martian ice it analyzed, mission also extended until September 30th (link); Microscopy, Electro-chemistry, and Conductivity Analyzer (MECA) instrument possibly detects perchlorate.
• News: Liquid lake discovered on Titan, believed to be full of ethane; European Space Agency (ESA) spacecraft Mars Express takes highest resolution image of Mars's moon Phobos ever (link); ESA spacecraft Rosetta starts tracking asteroid (2867) Steins in order to rendezvous with it on 5 September; book review in Nature on "The Black Hole War" by Leonard Susskind describing a debate between him and Stephen Hawking on the fate of black holes; NY Times article about new book "The Universe Mirror" by Robert Zimmerman about the challenges in getting the Hubble Space Telescope built and launched; congratulations to Mr. Enrico Saggese for being appointed head of the Italian Space Agency; congrats to Dr. Thomas B. Irvine for being appointed Deputy Associate Administrator of NASA's Aeronautics Research Mission Directorate; congratulation to the winners of NASA's first Aeronautics Scholarship competition - list of winners available here and more about this program available here; NASA unveils this webpage in honor of its 50th anniversary; NASA hosts an international meeting to discuss future lunar science missions, signs partnership agreement with University of Western Ontario; NASA's Lunar Reconnaissance Orbiter undergoes pre-launch testing at Goddard Space Flight Center; Solar Eclipse on morning of August 1 (link); NASA to broadcast highlights of its activity in HD on NASA TV.
• Calendar of upcoming Astronomy/science events in the greater New York City / Poughkeepsie Area.
• Star Formation: As described very well in an interview I did with Dr. Aki Roberge of NASA's Goddard Space Flight Center, stars form by the gravitational collapse of dense clumps (>100 of atoms per cubic cm) of material in molecular clouds, cold regions where atoms can stick together into molecules and dust grains (essentially, very large molecules with 100s of atoms stuck together). Therefore, the chemical composition of these molecular clouds are the building blocks of the chemicals we find in the Sun, Solar System, and on Earth. With radio telescopes, one can see spectral lines from these molecules, and in one molecular cloud, a primitive amino acid (acetonitrile) was discovered, while surveys for identifying other complicated molecules in molecular clouds are currently taking place (link). Miniature diamonds found inside meteorites can also form in these molecular clouds, and can be detected with the Spitzer Space Telescope. To determine how a molecular cloud breaks into dense clumps which will collapse into stars, it is important to know the distribution of material inside the molecular cloud. Since molecular clouds are extremely dense and cold, it is very hard to see into them because they absorb all the optical light behind them and don't emit much optical light of their own. However, molecular clouds scatter infrared light from stars behind them, and this scattered light can be observed, creating an effect called "cloud shine". Since denser regions scatter more light, the amount scattered light which one sees gives an estimate of the density. This approach is currently being applied to a large number of molecular clouds with ESO's New Technology Telescope and upcoming VISTA telescope. As clumps in the molecular cloud collapse into stars, these clumps can fragment, and the mass of these fragments are extremely important in determining the mass of the stars which form. Recent computer simulations by Dr. Krumholz and Prof. McKee of Princeton University suggest that, to form the most massive stars, the clump must have column density (density of material through the region, mass per unit area NOT mass per unit volumn) 1 gm / square centimeter, though this number depends on fraction of mass in elements heavier than H and He which are critical in the physics of how the gas increases in density by about a million times to become a star. Replicated this process on a computer is extremely difficult, and recently a new software code called "FEARLESS" has been developed to try and solve many of the problems (link). As the gas collapses into star, it doesn't collapse directly into a star but forms a disk of material which slowly moves inward to for the star. Recent observations of a forming star, DG Tau, has found collimated, fast moving material moving away from the central star which astronomer call a "jet". Many of these "jets" from forming star have been discovered, but the material in this one is so hot it produces X-rays that are absorbed by the material in the disk, possibly changing its chemical composition. Now, stars born at the same time, with the same mass, and out of the same material are expected to have identical properties. However, recent observations of a binary star system where one star passes in front of the other suggest that, despite having the same mass and age, they have different temperatures and radii which is extremely bizarre (link).
• Brown Dwarfs: Brown dwarfs are the least massive stars, only a few times more massive than Jupiter, and are believed to have too little mass to produce a hot core that fuses hydrogen into helium as out Sun does. As mentioned above, stars when they are form are often observed to power jets into their surroundings. Well, brown dwarfs were recently observed to do the same (link). Also, the coldest dwarf ever observed was recently detected, with a surface temperature of 350 Celsius, comparable to a pizza oven, and about 3x times colder than the surface of the Sun (link). Also, the mass and temperature of brown dwarfs orbiting each other have recently been measured, and differ from that predicted by models (link).

Sorry for the delay in posting this, and hope you enjoy. As always, any and all feedback will be very appreciated.

Partial Lunar Eclipse Saturday Night

This Saturday, some of the world has a chance to see a partial lunar eclipse which occurs when the Sun-Earth-Moon form a line, such that the Earth blocks sunlight from hitting the Moon's surface, causing it to go dark. It unfortunately won't be observable everywhere, so go here for more details as to where you can see it. Lunar eclipses can be quite pretty, so if you take any pictures and post them online, please leave the URL below. I'd love to see them!

Want to ask an astronaut a question?

Every week, NASA will be transmitting submitted question to astronaut Greg Chamitoff, currently on the International Space Station, who will record answers and send them back down to Earth. If you have a question for him, go here for details. He hopefully will return safely to Earth in November on the space shuttle Endeavor, so you have to submit you question before then. Good luck!

Perseid Meteor Shower

The Perseid meteor shower peaked last night / early this morning, and spaceweather.com has lots of amazing pictures of this event here. If you have your own pictures, please email me the URL or leave it below - I'd love to see them. And if you missed the meteor shower, don't worry you can still see some meteors for about another week and it should be back next year.

Hubble Space Telescope Competition

In honor of the Hubble Space Telescope completing its 100,000th orbit around the earth, hubblesite.org is sponsoring a raffle for a framing-worthy photography of this image of a star-forming region in the Large Magellanic Cloud taken by Hubble during this orbit. Good luck!

NASA Aeronautics Scholarship Program

Last year, NASA started a new scholarship program for undergraduate and graduate students, the winners of which were recently announced and can be viewed here. Congratulations to those who won, and for those interesting in trying in 2009, keep an eye on this webpage for forms and instructions. Good luck!