IYA "Live" Telescope Today
Written by Tammy Plotner
Did you get a chance to tune into Galactic TV today? That's right! We had a clear, dark night in Central Victoria and the IYA "Live" Telescope ran non-stop for almost 9 hours. We did it good, folks… And I know a lot of you remembered to look, because several times we topped out on how many were at the virtual eyepiece! Because we just might have clouds again tomorrow, let's just reveal two of our objects for today. Are you ready? Then lets have a look at the Small Magellanic Cloud and M77….
The Small Magellanic Cloud (SMC) is a dwarf galaxy. It contains several hundred million stars. Some speculate that the SMC was once a barred spiral galaxy that was disrupted by the Milky Way to become somewhat irregular. It still contains a central bar structure. At a distance of about 200,000 light-years, it is one of the Milky Way's
nearest neighbors. It is also one of the most distant objects that can be seen with the naked eye. With a mean declination of approximately -73 degrees, it can only be viewed from the Southern Hemisphere and the lower latitudes of the Northern Hemisphere.
It is located in the constellation of Tucana and appears as a hazy, light patch in the night sky about 3 degrees across. It looks like a detached piece of the Milky Way. Since it has a very low surface brightness, it is best viewed from a dark site away from city lights. It forms a pair with the Large Magellanic Cloud (LMC), which lies a further 20 degrees to the east. The Small Magellanic Cloud is a member of the Local Group.
Next up? Ah… A galaxy!
Messier 77 (also known as NGC 1068) is a barred spiral galaxy about 47 million light-years away in the constellation Cetus. Messier 77 is an active galaxy with an Active Galactic Nucleus (AGN), which is obscured from view by astronomical dust at visible wavelengths. The diameter of the molecular disk and hot plasma associated with the obscuring material was first measured at radio wavelengths by the VLBA and VLA. The hot dust around the nucleus was subsequently measured in the mid-infrared by the MIDI instrument at the VLTI. It is the brightest Seyfert galaxy and is of type 2. Messier 77's diameter is a 170,000 light-years. Messier 77 was discovered by Pierre Méchain in 1780, who originally described it as a nebula. Mechain then communicated his discovery to Charles Messier, who subsequently listed the object in his catalog. Both Messier and William Herschel described this galaxy as a star cluster. Today, however, the object is known to be a galaxy… A very active one!
Active galaxies are among the most spectacular objects in the sky. Their compact nuclei (AGN = Active Galaxy Nuclei) are so luminous that they can outshine the entire galaxy; "quasars" constitute extreme cases of this phenomenon. These cosmic objects show many interesting observational characteristics over the whole electromagnetic spectrum, ranging from radio to X-ray emission. There is now much evidence that the ultimate power station of these activities originate in supermassive black holes with masses up to thousands of millions times the mass of our Sun, cf. e.g., ESO PR 04/01. The one in the Milky Way galaxy has only about 3 million solar masses, cf. ESO PR 17/02. The black hole is believed to be fed from a tightly wound accretion disc of gas and dust encircling it. Material that falls towards such black holes will be compressed and heated up to tremendous temperatures. This hot gas radiates an enormous amount of light, causing the active galaxy nucleus to shine so brightly.
NGC 1068 (Cetus A) is among the brightest and most nearby active galaxies. Located in the constellation Cetus (The Whale) at a distance of about 50 million light-years, it looks like a rather normal, barred spiral galaxy. The core of this galaxy, however, is very luminous, not only in optical, but also in ultraviolet and X-ray light. A black hole with a mass equivalent to about 100 million times the mass of our Sun is required to account for the nuclear activity in NGC 1068.
Be sure to stay tuned to Galactic TV! We'll run the IYA Live Telescope whenever the skies are clear and save the video footage to store here in the library. If it's cloudy tomorrow? Hey… I'll show you what else we caught!
Factual Information courtesy of Wikipedia and ESO Outreach
Filed under: IYA 2009, IYA Live Telescope Library
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August 20th, 2009 at 9:10 am
Thanks for those great views, Tammy. While I wish I could sweep my scope across the SMC (and the LMC to boot!), they, of course, are below my horizon from Tampa, FL. M 77, OTOH, is quite a respectable sight through my (smallish) 4.25 inch reflector. I've had several fantastic views of this bright Seyfert through the mighty Warren Rupp reflector in the late 1970's and even a peek at it through the 88 inch(2.1m) Struve reflector at McDonald Observatory in Texas. Again, thanks to all involved in the IYA Live Telescope program and keep 'em coming