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Kullat Nunu
2004-Apr-16, 05:19 PM
Two new transiting planet canditates detected by the OGLE Survey have been confirmed by radial velocity measurements: OGLE-TR-113 (http://www.obspm.fr/encycl/OGLE-TR-113.html) and OGLE-TR-132 (http://www.obspm.fr/encycl/OGLE-TR-132.html). Both are so-called "very hot Jupiters" and their orbital periods are about one-and-half days for both. Their masses are a bit over one Jupiter, and they lie about 5000 light years away, and their parent stars are solar-like. Now known transiting planet count rises to four.

Third planet was detected by gravitational lensing by both OGLE and MOA projects. OGLE 2003-BLG-235 (http://www.obspm.fr/encycl/OGLE235-MOA53.html) aka MOA 2003-BLG-53 planet is 1.5 or 2.5 Jupiter masses and orbits its parent star at distance of 3 or 2.8 AUs. It is located in Sagittarius about 17,000 light years away. Its planet star is a dim red dwarf. In fact, the star and planet both were discovered simultaneously! More at BBC (http://news.bbc.co.uk/2/hi/science/nature/3631889.stm) and Space.com (http://www.space.com/scienceastronomy/exoplanet_new_0404015.html). It is the first definitive planet discovery by the gravitational lensing method.

And finally, I managed to spot this in the latest HST Daily Report (#3593):


NIC2 9845

NICMOS Confirmation of a Young Planetary-Mass Companion

We have recently discovered a strong candidate for a planetary-mass
{~10 Mjup} companion to a young Sun-like star, based on near-IR
imaging and spectroscopy with the Keck and Subaru adaptive optics {AO}
systems. While the ground-based data strongly suggest that the
candidate has a very low effective temperature, and hence a very low
mass, they are not definitive. We propose to obtain NICMOS
coronagraphy to measure the companion's 1.9um water-band absorption.
This feature is a distinct signature of very cool objects and is
unobservable from the ground. The combined ground-based and
space-based data set will determine whether the companion has a very
low temperature, and hence if it is the lowest mass companion found to
date by direct imaging.

Hopefully it will be proven to be a planet. :o

ToSeek
2004-Apr-16, 05:27 PM
JPL press release (http://www.jpl.nasa.gov/releases/2004/103.cfm)

Kullat Nunu
2004-Apr-16, 05:43 PM
I forgot the SuperWASP (http://www.superwasp.org) photometric survey which become operational today.
It is expected to find in next few years thousands of transiting planets!
See PPARC press release (http://www.pparc.ac.uk/Nw/superwasp.asp).

JohnOwens
2004-Apr-16, 08:16 PM
Just curious, anyone know what they use for a gravitational lens at those distances? I'm used to hearing about lensing around galaxies, but obviously that won't work for something a "measly" 17,000 ly away. Was it a regular star (seems difficult due to brightness of the would-be lensing star), a neutron star, or a chance occultation by a planet/moon/asteroid?

Added: Or, I could just read as far as the second paragraph of one of the linked stories. :roll: In case I got anyone else wondering, it was a star in between us and the planet's system.

Rain Dog
2004-Apr-16, 11:51 PM
Just curious, anyone know what they use for a gravitational lens at those distances? I'm used to hearing about lensing around galaxies, but obviously that won't work for something a "measly" 17,000 ly away. Was it a regular star (seems difficult due to brightness of the would-be lensing star), a neutron star, or a chance occultation by a planet/moon/asteroid?

Added: Or, I could just read as far as the second paragraph of one of the linked stories. :roll: In case I got anyone else wondering, it was a star in between us and the planet's system.

I think it's the planetary system itself that's acting as a lens. The observations are taken of a more distant object and and the variations in the lensing effect allow one to infer the existence of a planet in the system that's creating the lens.

-RD

JohnOwens
2004-Apr-17, 01:02 AM
I think it's the planetary system itself that's acting as a lens. The observations are taken of a more distant object and and the variations in the lensing effect allow one to infer the existence of a planet in the system that's creating the lens.
Oops! You're right; thanks for pointing that out. :) Guess the Bad Newbie can still teach the Bad Grad a thing or two. :wink: :oops:

Kullat Nunu
2004-Apr-18, 08:39 AM
The microlensing search method seems to be quite powerful, as it can reveal Earth-sized planets even with current instrumentation. Problem is, microlensing events are unique so we cannot get more information from the lensing planet - unless it passes over another star, event that is extremely unlikely. Microlensing is still very useful determining frequencies of different planets.

AK
2004-Apr-18, 11:09 AM
Both are so-called "very hot Jupiters" and their orbital periods are about one-and-half days for both.


It goes all the way around the star in 1.5 days? :o How close are these planets to their parent star? Wouldn't it have to be proportionately extremely close for such a small orbital period?

Kullat Nunu
2004-Apr-18, 11:49 AM
Both are so-called "very hot Jupiters" and their orbital periods are about one-and-half days for both.


It goes all the way around the star in 1.5 days? :o How close are these planets to their parent star? Wouldn't it have to be proportionately extremely close for such a small orbital period?

OGLE-TR-113 planet has a semimajor axis of 0.0228 AUs (~ 3,400,000 km) and OGLE-TR-132 planet 0.0306 AUs (~ 4,600,000 km). They still don't beat OGLE-TR-56 with distance of 0.0225 AUs. If their parent stars have about the same diameter as the Sun (1,400,000 km) they orbit at ~4.9-6.6 stellar radii!

shash
2004-Apr-18, 02:08 PM
Then the orbital period is of the order of... tens of days?

Kullat Nunu
2004-Apr-18, 03:12 PM
Then the orbital period is of the order of... tens of days?

Why so? Gravity decreases in inverse square, so objects very near star orbit much faster than further out.