Good old moon. It’s back again for another appointment with the planet Venus. Watch them this evening at dusk starting 20-30 minutes after sunset when they’ll light up the southwestern sky like a celestial holiday display.
On Monday Dec. 2 John Seach of Chatsworth Island, New South Wales, Australia, discovered a brand new nova in the constellation Centaurus the Centaur using only a camera with a standard 50mm lens. He photographed the region previously on Nov. 26; when he returned and re-photographed the same piece of sky, he noticed a bright star that wasn’t there before.
At discovery, the nova had already surpassed the naked eye limit at magnitude 5.5. Today, less than a week later, it’s rocketed up to magnitude 3.7; even under suburban skies the nova’s now an easy naked eye object. That’s brighter than Nova Delphini, which was discovered on August 14 this year and widely viewed by skywatchers around the world. Nova Del peaked two days later at 4.4 and has since faded to around 11th magnitude.
The only downside of the new discovery is that it’s only visible from equatorial and southern latitudes. Northern hemisphere skywatchers will have to sit this one out, watching from afar via the Web. But if you live in Australia, the nova stand high in the southeastern sky below the Southern Cross and near the two brilliant stars Beta and Alpha Centauri shortly before the start of dawn.
Likely still rising in brightness, Nova Centauri has already oogled its way into the Top 20 brightest novae ever recorded. I’d love to go down and see it, but my vacation time’s done for the year.
If you’d like to make a map of precisely where to look for the nova, please check out the AAVSO’s Variable Star Plotter. Click the link and type in Nova Cen 2013 and you’ll get a chart showing the star along with magnitudes of other stars you can use to estimate its brightness.
Just as there’s more than one variety of apple, there are different kinds of novae. All involve close binary stars with a compact white dwarf stealing gas from its companion. The gas ultimately funnels down to the surface of the dwarf where it’s compacted by gravity and heated to high temperature on the star’s surface until it ignites in an explosive fireball. This is what you see when you look at a nova – a gigantic bomb going off.
To be clear, a nova doesn’t involve the destruction of the star, only a “shock to the system”. A supernova is a different beast entirely, resulting in the complete annihilation of a white dwarf or supergiant star. If a white dwarf accumulates too much matter from a companion and crosses the Chandrasekhar Limit, it can sidestep the nova stage and go straight to supernova.
You lucky southern folks! Enjoy your new guest and let us northerners know how things are coming along.