March 2008. The
plot at right is a transit light curve of the extra-solar planet
XO-1b
observed at IRT on March 14, 2008 (0.025 mag eclipse depth, about 2%).
Of the dozen known stars with eclipsing planets, XO-1 is the most
similar to the Sun (spectral type G1V, distance 600 light yrs). The
transiting planet is also remarkably similar to Jupiter, with a radius
1.0x -1.3x Jupiter). However the planet is only 0.05 AU from its parent
star,
about 100x closer than Jupiter is to the Sun. This results in a 'year'
[orbital period] on XO-1b of only 3.9 Earth days. Although the mass and
size of the planet are very similar to Jupiter, the surface temperature
is much
higher than Jupiter (1,100 K = 1,520 F, vs. 110 K =
-264 F) because it is so close to its parent star. An
artist's conception of the
transit can be seen here.
The light curve was
created from 360 images using an R (red) filter with 40 sec exposures.
The data points have been median averaged with a smoothing window of 7
minutes. More details about the discovery of this system can be found here. | 
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April 2008. The
images at right are of the planetary nebula NGC 1501. The left-hand
image is a pseudo-color radio image taken on April 29, 2008 at the Very Large Array
by students in the course Radio
Astronomy, while the right-hand image is an optical tri-color
magnified image take at the IRO in January 2008. The
nebula's central ionizing star [visible in the optical image] is an
extremely hot Wolf-Rayet of spectral type WC4 with a surface
temperature of 110,00K. It has a large stellar wind with a
mass-loss rate of one solar mass every 10 million years. It's distance
is uncertain but is thought to be ~4,00 light years, with an age of
10,000 yrs. For a large-scale image of the NGC 1501 field, click here.
Although the nebula appears nearly uniform in density, current models
indicate that the nebula is shell-like, and that the ionizing gas
results from the interaction of the stellar wind with the surrounding
interstellar medium. By comparing the radio and optical data, we hope
to map the temperature distribution of the ionized gas. | 
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