Atmosphere of Exoplanets Sunday, Feb 25 2007 

From a NASA press release this week

NASA’s Spitzer Space Telescope has captured for the first time enough light from planets outside our solar system, known as exoplanets, to identify molecules in their atmospheres….

Spitzer, a space-based infrared telescope, obtained the detailed data, called spectra, for two different gas exoplanets. Called HD 209458b and HD 189733b, these so-called “hot Jupiters” are, like Jupiter, made of gas, but orbit much closer to their suns.

The data indicate the two planets are drier and cloudier than predicted. Theorists thought hot Jupiters would have lots of water in their atmospheres, but surprisingly none was found around HD 209458b and HD 189733b. According to astronomers, the water might be present but buried under a thick blanket of high, waterless clouds.

Those clouds might be filled with dust. One of the planets, HD 209458b, showed hints of tiny sand grains, called silicates, in its atmosphere. This could mean the planet’s skies are filled with high, dusty clouds unlike anything seen around planets in our own solar system…

The ‘More Info’ page on the press release links to two papers “A Spectrum of an Extrasolar Planet”
by L. Jeremy Richardson et.al.
and A Spitzer Spectrum of the Exoplanet HD 189733b by C. J. Grillmair et.al. apart from some podcasts.

And via BA Blog, we are reminded that “Twenty years ago, astronomers witnessed one of the brightest stellar explosions in more than 400 years. The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery on 23 Feb., 1987.” Of course, the article doesn’t quite spell it out that the neutrino detectors were telling us something interesting three hours before the explosion was seen ! (See this link too – via Backreaction blog .)

sn1987.jpg
‘Rings’ left by the Supernova Explosion

Advertisements

Physics Blogspeak : Part II Sunday, Jan 14 2007 

COSMOS Reveals the Cosmos (from Cosmic Variance by Sean)

The internet works so that we don’t have to! This week is the big annual meeting of the American Astronomical Society in Seattle, so expect to see a series of astro-news stories pop up all through the week. The first one concerns a new result from the Cosmological Evolution Survey (COSMOS) — they’ve used weak lensing to reconstruct a three-dimensional image of where the dark matter is.


AAS Report #3: Things that go boom! (From Bad Astronomy Blog)

It’s a fact of life that some stars explode. Actually, it’s a good thing: when stars explode they create and scatter the heavy elements that create us. The iron in your blood and the calcium in your bones were created in a supernova! So it’s important to study these objects, so we can better understand our origins.

But it’s also fun! Stars explode! Bang! Cool!

Today there were three press releases about supernovae. All three were surprising to me, and pretty interesting.

1) Kepler’s Supernova was a Type Ia

OK, so that title doesn’t thrill you. But that simple statement is actually the answer to a long-standing mystery. Ready for this? OK, sit back…

The AAS : a Nerd’s Eye View (from Galactic Interactions)

I’m in Seattle at the moment. I flew in yesterday; it’s cold, windy, and rainy. In fact, the rain was looking kinda slushy last night. While my wife from Minnesota might scoff at my calling this cold (it was just below freezing), in Nashville it’s been March-like temperatures.

I’m here for the 209th meeting of the American Astronomical Society. I’m going to try an experiment. I’ve never done the “live blogging” thing before, and indeed it’s entirely possible that I’m not using the term properly. It is my intention to post several posts this week inspired by things I see at the AAS. I can’t tell you what they will be yet, because they haven’t happened…. I’m hoping mostly to focus on interesting science and such, but anything that inspires me to blather is fair game as far as I’m concerned….

(Other posts in this series.)

Come On In, the Methane’s Fine (from Uncertain Principles by Chad Orzel)

The Times has an article announcing the discovery of methane lakes on Titan:

CDF’s New Results : W Boson Mass and Top quark Mass (From Quantum Diaries)

1)And the W mass is …
2) A summary Mw-Mt plot for Christmas 2006
3) More thoughts on the W mass
4) A new precise top mass measurement with jets
5) The new number

Happy Perihelion ! Wednesday, Jan 3 2007 

Via Bad Astronomy Blog, we are informed that

Today, January 3, on or about 20:00 Universal Time (2:00 p.m. Pacific time), the Earth will reach perihelion, its closest approach to the Sun. The distance from the Sun to the Earth will be roughly 147,093,600 kilometers (I have found several different distances on different sites, and this is an eyeball average).

with a statutory warning that

Remember, our distance from the Sun doesn’t affect our seasons (much).

So, Happy Perihelion ! 🙂

Don’t miss the The Top Ten Astronomy Images of 2006.

Now, last but not the least, via the same blog, I came across a treasure-trove for those who are interested in astronomy – What’s Up 2007 – 365 Days of Skywatching , a superb online book !

If somebody knows the present Astro-club co-ordinators, do pass on.

“Life of a Star” – KITP Blackboard Lunch Monday, Nov 20 2006 

Am just listening/seeing one of the “Blackboard Lunches” from (Kavli Institute of Theoretical Physics) .

I’ve already linked to an absolutely great series of talks online at the KITP site. But, I suspect that that one post hasn’t done justice to KITP …

But, this week I came across another set of “Blackboard Lunches” which are great too.

Now, I am seeing this one – The Life of a Star.

The Life of a Star
Dr. Lars Bildsten, KITP

Using only chalk and one figure, I will derive the luminosity, lifetime, and major properties of all stars and explain why their ultimate fate (white dwarf, neutron star or black hole) depends on their mass. After this event, you should be able to explain it to your family and friends.

It’s a great talk (from the first two minutes I gather that even “geologists and string theorists” can understand it 😉 ).

COBE gets the Nobel Tuesday, Oct 3 2006 

The history of science is filled with many a dead theory – theories which couldn’t stand up to the onslaught of experiments. But, once in a while, there comes a theory/a model which is so suceessful, so successful that it is just fun to watch graph after graph, observation after observation fit with what the model predicts.

Our present model of the universe had such a moment when COBE went onto measure anisotropies in cosmic microwave background.And it is this that the Nobel Committee has chosen to immortalise through the 2006 Nobel Physics prize. To quote them

This year the Physics Prize is awarded for work that looks back into the infancy of the Universe and attempts to gain some understanding of the origin of galaxies and stars. It is based on measurements made with the help of the COBE satellite launched by NASA in 1989.

The COBE results provided increased support for the Big Bang scenario for the origin of the Universe, as this is the only scenario that predicts the kind of cosmic microwave background radiation measured by COBE. These measurements also marked the inception of cosmology as a precise science. It was not long before it was followed up, for instance by the WMAP satellite, which yielded even clearer images of the background radiation. Very soon the European Planck satellite will be launched in order to study the radiation in even greater detail.

According to the Big Bang scenario, the cosmic microwave background radiation is a relic of the earliest phase of the Universe. Immediately after the big bang itself, the Universe can be compared to a glowing “body emitting radiation in which the distribution across different wavelengths depends solely on its temperature. The shape of the spectrum of this kind of radiation has a special form known as blackbody radiation. When it was emitted the temperature of the Universe was almost 3,000 degrees Centigrade. Since then, according to the Big Bang scenario, the radiation has gradually cooled as the Universe has expanded. The background radiation we can measure today corresponds to a temperature that is barely 2.7 degrees above absolute zero. The Laureates were able to calculate this temperature thanks to the blackbody spectrum revealed by the COBE measurements.

COBE also had the task of seeking small variations of temperature in different directions (which is what the term ‘anisotropy’ refers to). Extremely small differences of this kind in the temperature of the cosmic background radiation – in the range of a hundred-thousandth of a degree – offer an important clue to how the galaxies came into being. The variations in temperature show us how the matter in the Universe began to “aggregate”. This was necessary if the galaxies, stars and ultimately life like us were to be able to develop. Without this mechanism matter would have taken a completely different form, spread evenly throughout the Universe.

COBE was launched using its own rocket on 18 November 1989. The first results were received after nine minutes of observations: COBE had registered a perfect blackbody spectrum. When the curve was later shown at an astronomy conference the results received a standing ovation.

The success of COBE was the outcome of prodigious team work involving more than 1,000 researchers, engineers and other participants. John Mather coordinated the entire process and also had primary responsibility for the experiment that revealed the blackbody form of the microwave background radiation measured by COBE. George Smoot had main responsibility for measuring the small variations in the temperature of the radiation.
Read more about this year’s prize
Information for the Public(pdf)
Advanced Information (pdf)

You can find the telephone interviews of the winners here and here.Here is the link to the official wesite of the COBE and here are the links to various posts in physics blogsphere and around the web .

firas_spectrum.jpg
(Click to magnify)
From NASA site

Cosmic Microwave Background (CMB) spectrum plotted in waves per centimeter vs. intensity. The solid curve shows the expected intensity from a single temperature blackbody spectrum, as predicted by the hot Big Bang theory. A blackbody is a hypothetical body that absorbs all electromagnetic radiation falling on it and reflects none whatsoever. The FIRAS data were taken at 34 positions equally spaced along this curve. The FIRAS data match the curve so exactly, with error uncertainties less than the width of the blackbody curve, that it is impossible to distinguish the data from the theoretical curve. These precise CMB measurements show that 99.97% of the radiant energy of the Universe was released within the first year after the Big Bang itself. All theories that attempt to explain the origin of large scale structure seen in the Universe today must now conform to the constraints imposed by these measurements. The results show that the radiation matches the predictions of the hot Big Bang theory to an extraordinary degree….

The Titan surface – A View from Huygens(video) Saturday, May 6 2006 

Background : Nothing at all. This is a NASA video – and you know it is supposed be for “kids” 😉

cassini.jpg
Link: A View from Huygens

This is a multimedia video from Huygens. It is a bit large(15.4 MB) but it has some good pictures of Titan(one of the moons of Saturn) and is worth watching.

Posted by: Loganayagam.R.