Saturn with the Sun behind it and the Earth as one of the little specks of light on the left
Zooming in to the original image we can see Earth as one of the bright dots near the rings.
Earth
Tuesday, May 22, 2007
Beautiful Picture of Saturn with Sun Behind
Every once in a while an image comes from one of our telescopes in space that just blows the mind. Here is one I particularly liked. This is an image taken by Cassini of Saturn with the sun directly behind it.
Saturn with the Sun behind it and the Earth as one of the little specks of light on the left
Zooming in to the original image we can see Earth as one of the bright dots near the rings.
Earth
Saturn with the Sun behind it and the Earth as one of the little specks of light on the left
Zooming in to the original image we can see Earth as one of the bright dots near the rings.
Earth
Sunday, May 20, 2007
SN 2006gy and Pair Instability Supernovae
Like explosions? Well, supernovae are the biggest ones in the whole universe. Some can outshine their entire host galaxy and last week, astronomers observed their biggest one yet, called SN 2006gy.
SN 2006gy is the bright spot on the right. It's entire host galaxy is the darkish green blur one the left.
It came from a star more than 150 times the mass of our sun. It is an example of a very rare type of supernova called a pair instability supernova. In these kinds of supernova a high energy photon (gamma ray) coming from the fusion areas within the star spontaneously forms a particle anti-particle pair and is either deflected in a different direction when the two particles collide or not recreated at all, thus reducing the light pressure on the surface of the star. This allows gravitational forces to win out on the surface of the star, causing it to contract.
An illustration of the mechanisms involved in pair instability supernova.
When the gammas produce pairs of particles, they travel less on average, thus heating the innards of the star, thus causing it to produce more gammas. The process goes on until the core of the star explodes with more force than the gravity that holds the star together. This can only occur in stars with more than 130 times the mass of the sun. In lesser massed stars, the process may even out and lead to a semi-stable, pulsating star. In the big stars though, it can produce what we saw with SN 2006gy, namely, an enormous bang:
SN 2006gy is the bright spot on the right. It's entire host galaxy is the darkish green blur one the left.
It came from a star more than 150 times the mass of our sun. It is an example of a very rare type of supernova called a pair instability supernova. In these kinds of supernova a high energy photon (gamma ray) coming from the fusion areas within the star spontaneously forms a particle anti-particle pair and is either deflected in a different direction when the two particles collide or not recreated at all, thus reducing the light pressure on the surface of the star. This allows gravitational forces to win out on the surface of the star, causing it to contract.
An illustration of the mechanisms involved in pair instability supernova.
When the gammas produce pairs of particles, they travel less on average, thus heating the innards of the star, thus causing it to produce more gammas. The process goes on until the core of the star explodes with more force than the gravity that holds the star together. This can only occur in stars with more than 130 times the mass of the sun. In lesser massed stars, the process may even out and lead to a semi-stable, pulsating star. In the big stars though, it can produce what we saw with SN 2006gy, namely, an enormous bang:
Saturday, May 12, 2007
Gliese 581c Video
Just a good video I found giving a bit more info and some nice pictures about Gliese.
Friday, May 11, 2007
More Planet News
This week the interesting planet news continues. After last week’s massive news about Gliese 581 C, this week’s news seems pretty uneventful but it is still important in understanding the possibilities for extra solar planets. Many people may be left with a human-friendly impression of exoplanets after Gliese but the news about the temperatures on a couple of hot Jupiter planets should quickly bring those people back to the reality that most exoplanets are about as non human-friendly as is possible.
Firstly, the mapping of temperature distribution on HD 189733b shows that this planet ranges between 1200 degrees Fahrenheit on the hemisphere facing away from the star to 1900 on the hemisphere facing the star. The planet is tidally locked to its star, an inconspicuous yellow dwarf like our own star. The fact that the temperatures are not more radically different on the different sides of the planet suggest that there are some pretty ridiculous winds involved to spread the heat around, winds that scientists say could be as fast as 6,000 mi/hr. This is one of the rare times that astronomers have been able to map the full surface of an exoplanet according to temperature variations along its surface. Another interesting thing about the planet is that it goes around its star in only two Earth days and therefore is a close transiting planet. In fact, the HD 189733 system is one of our best resources for learning about close transiting planets like this.
Image of the temperature on the surface of HD 189733b courtesy of NASA
The second planet I want to talk about, HD 149026b, is even more disturbingly anti-humanity. It is one of the hottest planets ever observed with temperatures over 3700 degrees Fahrenheit! It is so hot that it is hotter than some low mass stars. This planet, unlike the other one, probably doesn’t have its heat spread around both sides. It is also pretty small for this type of planet and extremely dense with very intense gravity. Astronomers are proposing that it may be a very dark world because it is so hot. Most of the light and energy from the star is obviously being sucked up into the planet, without much being reflected off of it for us to see. All in all, this chunk of coal is one of the weirdest exoplanets discovered yet.
An artist's conception of HD149026b, the hottest planet ever seen. Courtesy of NASA.
Both discoveries were made by measuring changes in infrared radiation as these planets went behind their stars. The observations were performed with the Spitzer Space Telescope.
Firstly, the mapping of temperature distribution on HD 189733b shows that this planet ranges between 1200 degrees Fahrenheit on the hemisphere facing away from the star to 1900 on the hemisphere facing the star. The planet is tidally locked to its star, an inconspicuous yellow dwarf like our own star. The fact that the temperatures are not more radically different on the different sides of the planet suggest that there are some pretty ridiculous winds involved to spread the heat around, winds that scientists say could be as fast as 6,000 mi/hr. This is one of the rare times that astronomers have been able to map the full surface of an exoplanet according to temperature variations along its surface. Another interesting thing about the planet is that it goes around its star in only two Earth days and therefore is a close transiting planet. In fact, the HD 189733 system is one of our best resources for learning about close transiting planets like this.
Image of the temperature on the surface of HD 189733b courtesy of NASA
The second planet I want to talk about, HD 149026b, is even more disturbingly anti-humanity. It is one of the hottest planets ever observed with temperatures over 3700 degrees Fahrenheit! It is so hot that it is hotter than some low mass stars. This planet, unlike the other one, probably doesn’t have its heat spread around both sides. It is also pretty small for this type of planet and extremely dense with very intense gravity. Astronomers are proposing that it may be a very dark world because it is so hot. Most of the light and energy from the star is obviously being sucked up into the planet, without much being reflected off of it for us to see. All in all, this chunk of coal is one of the weirdest exoplanets discovered yet.
An artist's conception of HD149026b, the hottest planet ever seen. Courtesy of NASA.Both discoveries were made by measuring changes in infrared radiation as these planets went behind their stars. The observations were performed with the Spitzer Space Telescope.
Subscribe to:
Posts (Atom)