MessageToEagle.com - Four CfA astronomers, Zachory Berta, David Charbonneau, Jean-Michel Desert, and Jonathan Irwin,
together with six colleagues, used the Hubble Space Telescope to probe the atmosphere around the transiting super-Earth known
This exoplanet has a mass of 6.5 Earth-masses and a radius of 2.7 Earth-radii, and it orbits a small M-dwarf star (its
diameter is only 21% of the Sun's).
They used the Hubble infrared spectrometer to observe the planet as it transited
across the face of the star; as it did so, the planet's atmosphere absorbed light from the star, thus subtly altering
the star's intrinsic spectrum as we observe it.
Artist's impression of exoplanet with water
The intrinsic spectrum itself was carefully measured and subtracted after the transit.
A "super-Earth" is an exoplanet (a planet around another star) whose mass is between about two and ten Earth-masses.
Planets larger than this are closer to Uranus and Neptune in size (and perhaps in other physical properties as well).
The category of "super-Earth" currently refers only to the mass of the object, and not to its radius, its orbital distance
from the star, its surface temperature, or its atmospheric properties, although naturally astronomers are working hard to
identify super-Earths that might offer clues about the Earth in these features.
Of the 576 exoplanets whose basic parameters are currently approximately known, there are 36 in the super-Earth category.
Earlier models tried to predict what the atmosphere of this super-Earth might contain, based on ground-based
transit spectra of it and on our current knowledge of the atmospheres of the planets in the solar system.
For example, an atmosphere dominated by molecular hydrogen is one possibility; this is the situation in Jupiter.
But measurements made in three separate transits found no evidence for this scenario - nor were they consistent
with an equilibrium atmosphere composed of elements whose relative abundances are those of the average solar system.
Instead, the astronomers concluded that, unless the atmosphere has a thick top layer of clouds obscuring our view,
its probable composition includes abundant water vapor.
Probing the atmosphere around a planet orbiting a star 42 light-years away is a remarkable achievement and
an early step.
The infrared spectrum of the super-Earth GJ1214b. The circles show the measured intensity at each wavelength;
the bars show the uncertainties. Also plotted are some proposed model atmospheres - the best fitting ones contain water vapor.
Credit: Zachory Berta, 2012
Future observations of this and other transiting exoplanets will tell us more about the
atmospheres of exoplanets, and lead to a better understanding of how atmospheres
form, evolve, and behave under a wide range of physical conditions.
Abnormal Star Discovered In The 'Forbidden Zone'
A team of astrophysicists from Germany, France and Italy have discovered in the constellation Leo is an old star.
The star's existence raised at once many questions for scientists.
The object is definitely not as its "contemporaries" that appeared immediately after the Big Bang event.
Astrophysicist Resolves Paradox With Radio Millisecond Pulsars
Celestial objects known as pulsars are still full of secrets. It is takes time and many efforts to learn all their secrets. Previous studies reached
the paradoxical conclusion that some millisecond pulsars are even older than the universe itself. It was time to resolve this paradox.
The Eyes Of A Future Alien Astronomer - What Will They See?
Have you ever wondered what the Universe will look like for a future alien astronomer?
It will in fact be entirely different from what it is today.
One trillion years from now, an alien astronomer in our galaxy will have great difficulties figuring out how the universe began.
The Milky Way will have merged with the Andromeda galaxy to form the Milkomeda galaxy. Many of its stars, including our Sun, will have burned out.
Violent Dragon Clash Billions Of Years Ago
NGC 5907 is sometimes called the "Splinter" or Knife Edge Galaxy because of its unusual appearance.
It is a spiral galaxy lying in the Dragon constellation,
about 40 million light-years from Earth that could have been formed through a gigantic collision of galaxies, 8 to 9 billion years ago.