Exoplanetology

I know that the various methods of planet detection can be "mashed-up", such as how the transit method used in combination with radial velocity (if the plane of the extrasolar system is tilted enough to allow it) to gather more details about exoplanets. However, today is the first time i learned that the transit method can also be used in tandem with the gravitational microlensing method.

In an arXiv paper published today, Japanese scientists detail their observations regarding 'spikes' of the light curves "just before and after the transit, which is a peculiar feature of the gravitational lensing."

Basically, the gravitational lensing effect happens during transit, wherein the extrasolar planet plays the role of the lens. But the lensing effect becomes significant only when the orbital radius of the planet becomes larger than 10 AU. At such distances, they say that it is harder to obtain more information about the exoplanet because the orbital velocity and/or orbital period are difficult to measure.

But that difficulty is where the advantage of the observable lensing effect comes in. They claim that the rising spike, the sharp rise just before the ingress (or after the egress) of the transit, could be an excellent probe for finding planet parameters. They conclude that "it could be a novel observable for determining the physical parameters" of exoplanets.

Head on to this direct PDF link for more goodness and nice-looking geometric charts.

 

Last year, astronomers discovered a link between a star's lithium content and the presence of planets around it. The amount of lithium in Sun-like stars depends on whether or not they have planets. This discovery has partly been fueled by the research to solve the mystery behind the low levels of Lithium in the Sun, as compared to other solar-like stars. To which Garik Israelian declares, "The Sun lacks lithium because it has planets".
Applying this finding to planet-hunting makes it easy for us to find out whether a solar-type star is likely to have planets around it based on the star's lithium content.

Now, another fact is uncovered: that the star temperature is linked to the tilt of the planet's orbit close to it. Giant planets with "wonky" orbits mostly circle blistering-hot stars. Some of the orbits of these "hot jupiters" is so tilted that they orbit backwards in relation to the spin of their host star (which reminds me of the Kozai Mechanism).

With this new finding, I will never look at an exoplanet database the same way again. Seeing the orbital eccentricity of an exoplanet would render me to glance at it’s host star’s temperature, because there is a relationship between the two. Finally, looking at a table of exoplanets and stars is not so boring anymore. Patterns exist between the host stars and their planets. And it is indeed very exciting to uncover hidden links within these ever-growing data on stars and exoplanets.

Links:
http://www.eurekalert.org/pub_releases/2009-11/e-ect110909.php
http://www.wired.com/wiredscience/2010/06/giant-tilted-exoplanets-like-it-hot/

I came across The Interplanetary Transport Network (ITN) and wondered if there's an equivalent Exoplanetary Transport Network (ETN) to take interstellar probes to exoplanets. After a quick search on the internet, I came across a recent article over at Centauri Dreams about an interstellar context of the ITN. Paul Gilster makes reference to Karl Schroeder's essay about an idea called "Cyclers", a way to travel across the stars.
In my mind i was looking for some mapping of the motion of nearby stars and where they would be after a certain amount of time. Kind of similar to the "tubes" of the ITN pictured above, would there be equivalent interstellar pathways for probes that we'd like to send to Alpha Centauri, or Epsilon Eridani? This kind of planning and mapping spans hundreds, thousands, or perhaps millions of years into the future. Since stars are in constant motion as they bob their way up and down around the Milky Way (for example, see Barnard's Star), most of them will not be in the same spot that we know of within 500 years from now. Some of them may not be "close" enough to us after a thousand years. But some might eventually become good targets for interstellar probes thousands of years from now.
I wish someone, or some organization, would start and maintain an Interstellar Route Map (IRM) and update it according to the motion of the stars relative to our Sun. With this map one can propose new interstellar routes according to new findings, such as the potential discovery of nearby Brown Dwarfs by WISE, which might be nearer to us than Alpha Centauri. The IRM will also be updated in relation to the technological and economic capabilities of mankind at a projected time of sending probes to extrasolar planets.
The Interstellar Route Map, if ever conceived, would be maintained through generations and handed down to progeny spanning hundreds and thousands of years in the future.

This truly is a wonderful post from Greg Laughlin of Systemic. These are the kinds of discoveries that make my heart jump and my jaw drop from the awesome nature of our universe. Greg starts by mentioning that "the Galilean satellites of Jupiter constitute the original exoplanetary system." As a matter of fact, Jupiter is like a "mini-solar system" which provides plenty of resonant insights even for Astronomers studying extrasolar systems. With that thought, I am hooked to read the rest of the article. It gives a Sensawunda with a glimpse on the Fractal Nature of our universe.

Links:
http://oklo.org/2010/06/23/a-second-laplace-resonance/

So far, there are two known exoplanets with raging storms: HD
209458 b and HD 80606 b. But the former is making waves in the news
right now.
New observations show that this gas giant HD 209458 b has superstorms
with toxic winds of 5,000 to 10,000 km per hour.
But here's the scoop: HD 80606 b beats HD 209458 b's storm-windspeed
by a large factor. The raging storm on HD 80606 b is faster than the
speed of sound: 3 miles per second!
The excellent thing is that the storm on HD 209458 b has been observed
by an actual scientific instrument, VLT's spectrograph. While that on
HD 80606 b has simply been predicted by computer models, based on it's
highly eccentric orbit--where wild variations in its weather cause
"shock wave storms". Of course that can't be beaten by HD 209458 b,
except for one thing: It has a cool nickname. Osiris.

Links:
http://news.bbc.co.uk/2/hi/science_and_environment/10393633.stm
http://www.scientificamerican.com/article.cfm?id=extrasolar-doppler-winds
http://news.discovery.com/space/exoplanet-storm-winds.html
http://www.labspaces.net/104638/VLT_detects_first_superstorm_on_exoplanet

Astronomers released today a paper about the discovery of a Uranus-like planet orbiting GJ 876, a red dwarf star. This is the 4th planet to be discovered in the GJ 876 system which lies in the Aquarius constellation with an apparent magnitude of 10.274. And GJ 876 e is the first example of a giant planet orbiting a low-mass star and so much more. The authors are quite psyched about it. In their words:
“This otherwise unassuming red dwarf has produced the first example of a giant planet orbiting a low-mass star, the first instance of a mean-motion resonance among planets, the first clear-cut astrometric detection of an extrasolar planet, and one of the first examples of a planet in the hitherto unknown mass regime between Earth and Uranus.”

Links: 
The Lick-Carnegie Exoplanet Survey: A Uranus-mass Fourth Planet for GJ 876 in an Extrasolar Laplace Configuration

For an update on the ongoing snafu regarding the public release of Kepler data, I'd like to report that the Kepler team released some data indeed. But not all of them.
So far, i can see that only the lightcurves are being released to the public, but not the actual CCD data.  For example, to grab the lightcurve of the candidate KIC 008394721, simply go to this URL: http://archive.stsci.edu/pub/kepler/lightcurves/0083/008394721/ and you can download the FITS file.
But if you head to the MAST website to search for the CCD data of the new candidates, the result would be empty.
For me, that is OK. I understand and I can wait. I have a feeling that the floodgates to the data will *only* be opened after the first earth-sized planet has been confirmed by the Kepler team. And yes, I would like them to be the one to find it, and announce it. The joy and the privilege of doing such a momentous task of discovering and announcing the first earth-twin belongs to the team that have worked so hard and dedicated their lives to a wonderful mission such as this.

This is definitely the next step in the evolution of transit analysis: Multi-planetary Transits! To date, I believe there is no known transiting exoplanet that is part of a multi-planet system. And thus, it is exciting to look at this arXiv paper which gives nice details on how you can go about analysing transit data to look for transits of multiple planets. If you think 2 planets is quite a challenge, then imagine analyzing for 3 planets! In fact, there is one stellar candidate for that, interestingly named "KOI 152" (Kepler Object of Interest), also known as KIC 8394721. So take a look at the nice charts and graphs and marvel at the challenges that our busy planet-hunters are up against! 
http://arxiv.org/abs/1006.2763

 

http://www.physorg.com/news195720221.html
http://www.ox.ac.uk/media/news_stories/2010/100614.html