September 23, 2014

Astro-Challenge of the Week: Can you Spot the Brightest Quasar?

(Credit: (NASA/CXC/SAO).

(Credit: (NASA/CXC/SAO).

The luminous jet of 3C 273 in X-rays.

   This week, we here at Astroguyz are going to show you how to go after that most elusive of beasts; a quasar. Even seasoned amateurs do not always realize that some of the brighter denizens of this elusive class of beasts are bag-able with a telescope of moderate-sized aperture. Of course, don’t expect to see much; part of the fun of this challenge is the fact you can see it at all, and the wonder of what the object actually is. Our visual prey is 3C 273 is the constellation Virgo. This object was the 273th listed in the 3rd Cambridge Catalog of radio sources, and at a 16% red-shift, stands at “only” about 2 billion light years distant! This also gives it an apparent recessional velocity of 30,000 miles per second. Visually, 3C 273 hovers at about magnitude +12.2, although it has been known to vary by about magnitude 0.5 in either direction. Its coordinates are;

Right Ascension: 12 Hours 29 minutes 6 seconds.

Declination: +02° 03’ 06” N

A good series of finder charts courtesy of the AAVSO may be had here; 3C 273 is about 4.7° NW of the star Gamma Virginis and very near the galaxy NGC 4536.

Now for the mind-blowing part; the absolute magnitude of 3C 273 is about -26; if this object was 10 parsecs distant, it would visually rival our own Sun! Its output also tops our own Milky Way galaxy by a factor of x100! As you can see, writing a post on the topic of quasars demands the extreme over-usage of exclamation points. 3C 273 is a worthy target for aperture 6” or greater, and stands as the farthest object you’ll probably ever lay eyes on. It also serves as a good reply to that common neophyte question heard at star parties; “So, how far can you see with that thing?” And just think, the light left 3C 273 when the Proterozoic era was the newest, greatest thing here on Earth… imaging may even help you grab this beast. Amateurs have even successfully recorded a spectrum of 3C 273 and measured its red-shift, a good reply next time someone asks you; “Yeah, but how do YOU know the universe is expanding?”  As the waning Moon slides out of the evening sky, I invite you add a quasar to your visual athlete-life list!

This week’s astro-word of the week is Quasar. Short for Quasi-Stellar object, this class of amazing objects was not even heard of until the early 1960s. Much controversy raged for decades as to exactly what astronomers were seeing; theories ranged from white holes to anti-matter fueled stars in the early universe. With the advent of accretion disc theory as a massive energy source outlined in the 1970’s a model of quasars slowly emerged; the consensus now is that we are seeing highly energetic galactic nuclei early in their youth. Perhaps the supermassive black hole at the core of our own Milky Way Galaxy was once a quasar itself, gobbling up interstellar matter and emitting massive amounts of x-rays and radio waves before settling down to the relatively placid state we see today. Other classes of objects such as blazars and radio galaxies have further filled in the classification gaps, and the massive amounts of energy we see in some quasars are thought to simply be the result of our viewing angle here on Earth. The brightest quasars devour perhaps 1000 solar masses of material a year, and the most distant recorded is CFHQS J2329-0301 discovered in 2007, with a red-shift of 6.43 and about 13 billion light years distant. This puts it in the realm of the very early universe, which is only 13.7 billion years old!

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  1. [...] This post was mentioned on Twitter by David Dickinson. David Dickinson said: http://bit.ly/9UXJ08 Astro-Challenge of the Week;Can you spot the Brightest Quasar?Never seen one?Astroguyz will show you how. [...]

  2. [...] y los astrónomos incluso utilizaron una serie de ocultaciones de la fuente de radio 3C 273  en 1962 para precisar la posición de la primera [...]

  3. [...] y los astrónomos incluso utilizaron una serie de ocultaciones de la fuente de radio 3C 273  en 1962 para precisar la posición de la primera [...]

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