MESSENGER And Vulcanoids; GAMMA Ray Star
Hello, astro-nuts!
It's Wednesday; be sure to check out the latest astronomy video, which covers astronomical events for next week! Our friends at Hubble also have a great video that covers big events throughout February!! Some big news today involves the spacecraft MESSENGER searching for Vulcanoids, and the activity of a Gamma-Ray Flare Star.
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As many of you may know, 2009 has been designated the International Year of Astronomy, and the most anticipated IYA event is the 100 hours of Astronomy, from April 2-5. There are plans on both small and large astronomical scales to celebrate the event, from sidewalk events at the local level, to a 24-hour live observing webcast from the largest telescopes in the world (5am EDT April 3 to 5am EDT April 4). Even before that takes place, NASA, on February 15th will be releasing images from its "great observatories". These observatories include Hubble Space Telescope, Spitzer Space Telescope, and the Chandra X-ray Observatory. More than 100 planetariums, nature centers, museums and schools throughout the U.S. will get to unveil a 9-square-foot image of Messier 101, the "Pinwheel Galaxy", which combines the optical view from Hubble, the infrared view from Spitzer, and the X-ray view from Chandra. Smaller whole images of the galaxy taken by each observatory will also be displayed. February 15th was chosen because it is Galileo Galilei's birthday, and I will talk more about him in Friday's posting. Speaking of Hubble, I mentioned in a previous posting that the group is looking to the public to vote for which celestial object Hubble should study next. Head to the website to cast your vote; before March 1; the winning image will be released during the 100 Hours of Astronomy. Check out the related video on the Hubble website, too!
Comet Lulin continues to make its way across the early morning sky, and is now heading towards the constellation Virgo. Unfortunately, a nearly full moon is interfering with views of the comet right now. No worries though, the Moon will be out of the way soon enough, and in plenty of time for the best few on the 24th. You can still view the comet, it just will not appear as impressive as it would without the moonlight around.
The sun put on a bit of a show last evening as it released a B1-class flare. B-class flares are considered to be relatively small and unremarkable; however, because solar activity has been pretty minimal lately, this was big news. NASA's STEREO-B spacecraft took some images of the event before and just after the eruption. The source of the eruption appeared to be a collapsing magnetic filament (the filament was not present after the event took place). For perspective, the types of solar flares, from weakest to strongest, are as follows: A, B, C, M, and X.
Astronews!
The MESSENGER spacecraft continues its orbital trek around the inner solar system, and will reach its closest distance from the sun today; 28,816,300 miles! This close proximity to our star provides an excellent opportunity for MESSENGER to be on the look out for small, rocky asteroids that are located in the orbit around Mercury as it in turn orbits the Sun. These asteroids are called Vulcanoids and so far have eluded astronomers. These rocks supposedly exist within the gravitationally stable area between the orbit of Mercury and the Sun. This would mean that any objects that formed there could have remained, even after billions of years. We know that all the other orbital regions in the solar system have some kind of space debris, such as the Kuiper Objects. The area that is in question for existence of Vulcanoids is very difficult to observe from Earth because of the proximity to the Sun. So far, objects 30 miles in diameter have been detected, and the hope is that MESSENGER can find some that are even smaller, perhaps nine or ten. Since February 7th, MESSENGER's Mercury Dual Imaging System has taken over 250 images in areas east and west of the sun. If these elusive rocks are found at all, let alone in greater numbers, it would pretty much confirm that they are the cause for all the craters on Mercury, and that various geological processes occurred earlier than we thought (since it was assumed the craters were formed along the same timelines and by the same bodies as those cratering the Moon and Mars). To date, MESSENGER has traveled more than 3,115,650,000 miles.
A neutron star 30,000 light-years away in the southern constellation Norma has been acting up recently. The star, named SGR J1550-5418, is known as a soft-gamma-ray repeater; only one of six known. These types of stars emit gamma-ray flares in rapid succession, then have periods of quiet. Several of the more intense flares have been emitting more energy at one time than our sun does in 20 years, and has been known to emit 100 flares in 20 minutes! Back in October, "J1550" emitted a few moderate flares, then went quiet until late January, when an intense episode of flare ups occurred. Using an X-ray telescope aboard the Swift spacecraft, the first "light echoes" from a gamma-ray repeater were observed and appeared as expanding halos around the star. As the X-rays interacted with dust clouds nearby, multiple "rings" were observed. A neutron star may be small, around 12 miles across, but there's much more mass within that small area than there is within the entire sun. A neutron star with an especially strong magnetic field is known as a magnetar, and it is thought that J1550 falls under this category. Flares from the star have been detected by NASA's Fermi Gamma-Ray Space Telescope at least 95 times since January 22nd, and the INTEGRAL satellite has also detected them.
Keep your eyes to the sky and enjoy the view! ~Lisa C.
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