Another mystery about stellar evolution may have an answer. A group of astronomers looking at globular clusters think they have figured out the origin of a particular type of star known as a blue straggler. The evidence is not concrete but definitely seems to present a plausible answer to a plaguing mystery.

Globular clusters are tightly bound groups of stars that live on the outskirts of galaxies. They make for interesting places of study since usually most of the stars within a particular cluster formed around the same age, so studying different clusters of different ages gives us information about star’s evolutionary paths. Most globular clusters are quite old though, as opposed to open clusters which are usually much younger, and globular clusters are not producing any new stars. Almost every star in a globular cluster is an older star, at least several billion years old. So herein lay the mystery.

In many globular clusters a certain type of star was observed, blue stragglers. Blue stragglers are very massive hot blue stars. Normally, hot massive blue stars are considered young when they are observed because if it is born that hot and massive it will burn out its fuel generally in several million to a few hundred million years. So the problem with finding them in these globular clusters is that since we know the clusters are much older than a few hundred million years these stars should not exist there. So how is it that these stars are where they are and look how they look??

There were two general theories about how these stars are formed. The first involved collisions between stars. You have two stars of medium mass colliding to make one massive star. The other theory was that of stellar cannibalism, in which one star in a binary system feeds of the mass of the other star. Binary systems are just those that contain two stars orbiting around and interacting with each other.

Researchers set out to answer this question by looking at 56 globular clusters. They found that the predicted number of collisions did not match that which was required to give the number of blue stragglers, thus dispelling that theory. They did, however, notice a correlation between the mass contained within the core of the cluster and the number of blue stragglers. It is known that the more massive the core is the higher numbers of binary systems exist within it. Thus they could infer a relationship between number of binary systems and the number of blue stragglers, seeming to support the second theory. This conclusion is also supported by direct observation of the number of binary systems in cluster cores. All of this points toward stellar cannibalism as the explanation. This would not be the only instance of stellar cannibalism in the galaxy. It has been seen many times in binary systems where one star is massive, usually a red giant, and the other is a white dwarf, or already dead star. The smaller white dwarf accretes matter from its larger partner until nuclear burning reignites on the star causing a nova explosion.

The next step for these researchers is to try and find out some information about the original two stars in the binary system, or the parents of the blue straggler. There must be something special about these binary systems that initiates the cannibalism. Are they mostly isolated, or could dynamical interactions between the system and nearby stars be a factor? It’s interesting that we do know a lot about stellar evolution and dynamics but there is always new and interesting ways in which the universe is trying to stump us.

NASA’s most recent balloon trip has found something new and unexplained, don’t you just love when that happens. The ARCADE balloon mission has uncovered a new radio signal with unknown origin, which may be more of an interesting find than the balloons real mission.

The findings come from NASA’s balloon borne instrument known as Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission, or ARCADE. ARCADE was launched in July of 2006 in Palestine Texas. It flew to an altitude of 37km, 120,000 ft, where the atmosphere thins and begins to give way to space. It took data for about 4 hours before parachuting back to Earth. Balloons like this one are used for this reason, they can get above the interference caused by our atmosphere but are much cheaper to launch and build then a full blown satellite.

ARCADE’s mission was to observe and collect radio data from some of the first stars born in our universe. Since these stars are so distance their light is only observable at radio wavelengths. For the instrument to be sensitive enough to pick up this information it had to be cooled, really cooled. It was sent up with 500 gallons of liquid helium to keep it at a frosty 2.5 degrees Celsius above absolute zero. So it was all poised and ready but the data it was sent to collect was lost in a powerful radio signal of unknown origin.

This background radio signal was about 6 times larger than what they had expected to find. It was too strong, or loud, to be coming from the distant stars, and even too loud to be coming from known radio sources like gas from the halo of our galaxy. All galaxies give off some radio noise, usually just a hiss, except for those which are radio loud, usually quasars. But even with all these radio loud galaxies there isn’t enough of them to account for this noise, for the noise to be coming from just galaxies there’d have to be so many radio galaxies they’d be packed in like sardines, one right next to another, which just isn’t the case.

So obviously there’s something that we are missing, something loud making this racket that we don’t even know about; and that’s exciting. This is a great example of why astronomy is so exciting. This routine type mission that was supposed to just give a few details on a particular type of star and then BAM! There’s a mystery with possible far reaching implications. Is this a new object all together? Is it an evolutionary stage of galaxies that we didn’t know about? NASA hasn’t yet mentioned any planned follow up to try and dig deeper into this mystery but I’m sure that it is coming, I mean everyone loves a good mystery.

On Friday the 13th, of April 2029 an asteroid approximately 330 meters in diameter will transverse the Earth’s orbit, coming nearer to the Earth than any other known asteroid in recorded history. Apophis was discovered in 2004 and after six months of optical and radar observations it was concluded that this asteroid will pass within 35700 km of the Earth, which is an altitude less than that of our satellites in geocentric orbit. Apophis will once again return on 2036, and astronomers say that if the asteroid’s center of mass passes through a small gravitational keyhole in the Earth’s atmosphere in 2029, Apophis’2 2036 orbit could be redirected into the Earth. Astronomers currently rank this asteroid has having little chance of impact, and is 0 on the Torino Scale.

The Torino scale is a scale from 0 to 10 that indicates the threat level of Near Earth Objects (NEO). A zero indicates that there is either no threat of impact, or that the object is too small to penetrate the atmosphere. A ten indicates that the object is likely to impact catastrophically. A NEO is assigned an integer value on the 0 to 10 scale based on impact probability and its kinetic energy. On December 23, 2004, Apophis had been given 1 in 233 chance of impact and a 2 on the Torino scale (Apophis is the first asteroid to have a value larger than 1 on the Torino scale). Later that day the odds of impact were increased to 1 in 64 with a 4 on the Torino scale. By 2006 the chance of impact has been reduced to 1 in 45,000 with a zero on the Torino scale.

In April 2008, a thirteen year old from Germany calculated the chances of collision to be 1 in 450 by factoring changes in the Asteroid’s orbit due to collisions with one or more geosynchronous satellites. To eliminate rumors that NASA and the ESA confirmed these calculations, NASA released a statement saying that the angle of approach relative to Earths equator, and the relatively small size of the satellites leave little or no chance of a satellite-asteroid collision.

Even though NASA has placed a low probability of impact, the threat is real enough that NASA plans on somehow deflecting the asteroid away from the tiny keyhole to prevent a future impact scenario. Some of these plans include nuking the asteroid, painting one half of it white, or by tugging it away using the gravitational pull of a probe. Nuking the asteroid has basically been ruled out because that may just result in showering us with several asteroid segments instead of one large one. Painting half of the asteroid white would result in the painted half of the asteroid reflecting more photons and thus pushing the asteroid in the desired direction, but this solution is impractical. Even if a good plan is developed it will do little good without precise and accurate details and calculations of the asteroid.

In 2008 the Planetary Society developed a $50,000 competition for the best mission designed to track the asteroid, and perform trajectory calculations for a year with an unmanned probe. The goal of the competition is to help Earth’s governments decide whether or not the probe should be deflected. The Planetary Society received 37 entries from 20 countries. The winning entry was designed by an Atlanta based company called Spaceworks Engineering. This plan called ‘foresight’ is planned to launch in 2012, after 5 months of travel it will rendezvous with Apophis, orbit it for one month while taking measurements with a multi-spectral imager. Once the orbiting phase is complete, the probe will follow Apophis around the sun for 10 months while it takes careful measurements of the asteroids orbit.

On Friday the 13th, in April of 2029, Apophis will be observable with the naked eye as it passes over the Earth at a distance of approximately 1/10 that of the moon. If you happen to be watching as the large asteroid come closer to the Earth than any other large asteroid in human history, remember one thing: even though calculus is perfect, the people who use it are not.

The Kepler Spacecraft is one step closer to launch. The Kepler spacecraft is set to launch in March of 2009, and its now packed up and ready to ship off to Cape Canaveral.

The launch of the Kepler Spacecraft will be an exciting one for planet hunters. It is named for the Dutch astronomer/mathematician Johannes Kepler who back in the 1500s derived some very important empirical laws describing planetary orbits. This spacecraft will be the most advanced piece of technology in the ever-growing arsenal used to detect exosolar planets. Kepler will monitor more than 100,000 stars simultaneously for signatures of planets of all sizes and orbital distances including earth sized planets. It will have the ability to detect rocky planets like Earth and ones that are located in the habitable zone of a star. For those unaware, the habitable zone is the area surrounding a star where the temperature i.e. distance from the star is such that life is possible. So in our solar system the habitable zone is more or less where Earth is and out to Mar’s orbit. So Kepler is not only expected to be the first to measure a Earth sized planet around a similar star but hopefully it should be able to tell us if they are rare or common, and thus whether possible life is rare or common.

Kepler is currently at the Ball Aerospace & Technology Corporation in Colorado, ready to leave for Florida. It hasp assed all its environmental tests and its pre-ship review. It will be launched atop a Delta 2 rocket and sent into an earth trailing solar orbit. It will be a solar orbit as opposed to the usual earth orbit so that earth will not obstruct its view of the stars since it will need considerably long exposure time to see such small planets. The telescope will be pointed at Cygnus, which is outside the elliptic of the solar system, which will prevent sunlight from obstructing the view of outside stars. Looking at Cygnus will also keep objects form the Kuiper Belt and asteroid belt from obstructing the starlight. The telescope will have a 1.4-meter mirror on it, the largest of any space based telescopes yet.

So with any hope the mission will launch as scheduled on March 5th. It has already been delayed several times due to budget issues (it was originally scheduled to launch in 2006 and is costing an estimated $467 million dollars). NASA other original mission to hopefully find earth-sized planets, the Terrestrial Planet Finder, was cancelled due to budget issues. But I think that this is one area in astronomy right now that has the most public support, so the most chance to receive funding. The general public may not be so concerned with something like WMAP (a spacecraft used to study the cosmic microwave background radiation) but the general public knows about finding other planets, about finding life outside of here; that is something easy to understand and still very exciting. So hopefully if Kepler is successful it will not only renew some lost passion for astronomy by the general public but also generate funding for future projects.