A Naked-Eye Nova in Centaurus

[Sky Watch]

A bright nova popped  last week in the southern constellation Centaurus.   Formally called Nova Centauri 2013 (or Nova Cen 2013), it was discovered December 3 by nova hunter John Seach in New South Wales Australia when it was already magnitude 5.5, just bright enough to see without optics.  The nova has brightened to magnitude 3.5 in the past two days, which makes it one of the brightest novae of the past century. 

An animation showing a comparison between the constellation Centaurus before and after a nova eruption. Credit and copyright: Ernesto Guido, Nick Howes and Martino Nicolini/Remanzacco Observatory. 

While it’s starting to slowly fade, the nova remains quite obvious as an interloping star in Centaurus not far from the bright stars known as the “Southern Pointers”, α Centauri (Rigil Kent) and β Centauri (Hadar).  This excellent image published at APOD shows you where to look.

(The image at the top of the page was taken remotely by Ernesto Guido, Nick Howes & Martino Nicolini at the Remanzacco Observatory in Italy).

This time of year, you need to wait late into the evening for these stars to rise high enough above the southern horizon.  The Southern Pointers are directly below Crux.  The nova is visible only to observers in the southern hemisphere, or at least well south of the Tropic of Cancer.  Observers in the deep-southern hemisphere… South America, South Africa, Australia, and New Zealand will get the best view.

The sudden brightening of a classical nova such as Nova Cen 2013 results when hydrogen gas from one star falls onto a nearby white-dwarf companion star.  When enough mass builds on the surface of the hot white dwarf, the hydrogen explodes in a sudden spasm of nuclear fusion, causing the star to brighten thousands of times.  Neither star is destroyed, however, and the process may repeat itself in hundreds or thousands of years.

A nova such as this is not particularly rare.  There was another bright nova in the constellation Delphinus earlier this year.  But it is unusual for a nova to brighten to naked-eye visibility.  Nova Cen 2013 is so far the brightest nova of this young millenium.

The brightest nova in recorded history flared in 1918 in the constellation Aquila.  Called V603 Aquilae, this star brightened to magnitude -1.4 and rivaled Sirius, the brightest star in the sky.

- See more at: http://oneminuteastronomer.com/9368/nova-centaurus-2013/#sthash.olo...

So, who can see Nova Cen 2013, and who’s left out?

Well, the coordinates for the nova are:

Right Ascension: 13 Hours 54’ 45”      Declination: -59°S 09’ 04”

That puts it deep in the southern celestial hemisphere sky where the constellation Centaurus meets up with the constellations of Circinus, Musca and the Crux. Located within three degrees of the +0.6^th magnitude star Hadar — also named Beta Centauri — it would be possible to capture the southern deep sky objects of the Coal Sack and Omega Centauri with Nova Cen 2013 in the same wide field of view.

The field of view of Nova Centauri 2013 with a five degree Telrad “bullseye” added for scale. Note that magnitude for selected comparison stars are quoted, minus the decimal points. (Created using Stellarium).

Though Nova Cen 2013 technically peeks above the southern horizon from the extreme southern United States, the viewing circumstances aren’t great. In fact, the nova only rises just before the Sun as seen from Miami in December, at 25 degrees north latitude. The Centaurus region is much better placed in northern hemisphere during the springtime, when many southern tier states can actually glimpse the celestial jewels that lie south, such as Omega Centauri.

But the situation gets better, the farther south you go. From Guayaquil, Ecuador just below the equator, the nova rises to the southeast at about 3 AM local, and sits 20 degrees above the horizon at sunrise.

11PM local, from latitude 40 degrees south looking to the southeast. (Created by the author using Starry Night Education Software).

The nova will be circumpolar for observers south of -30 degrees latitude, including cities of Buenos Aires, Cape Town, Sydney and Auckland. Remember, its springtime currently in the southern hemisphere, as we head towards the solstice on December 21^st and the start of southern hemisphere summer. We’ve been south of the equator about a half dozen times and it’s a unique experience – for northern star gazers, at least – to see familiar northern constellations such as Orion and Leo hang “upside down” as strange a wonderful new constellations beckon the eye to the south. Also, though the Sun still rises to the east, it transits to the north as you get deep into the southern hemisphere, a fun effect to note!

Latitudes, such as those on par with New Zealand, will get the best views of Nova Cen 2013. Based near latitude 40 degrees south, observers will see the nova about 10 degrees above the southern horizon at lower culmination at a few hour after sunset, headed towards 40 degrees above the southeastern horizon at sunrise.

Read more: http://www.universetoday.com/106932/a-naked-eye-nova-erupts-in-cent...

[1yrns4vean19o]

Astrophoto: Nova Centauri 2013 Turns Pink

This image taken on Dec. 28, 2013 from New Zealand shows Nova Centauri 2013, a bright naked eye nova in the Southern constellation of Centaurus. The nova appears pink because of emissions from ionised hydrogen. Credit and copyright: Rolf Wahl Olsen.

A recent naked-eye visible nova that erupted the first week in December 2013 is still showing its stuff, and this new “hot off the press” image from Rolf Wahl Olsen in New Zealand reveals its unusual color. “I managed to grab a close-up of Nova Centauri 2013 with my new 12.5″ f/4 scope,” Rolf said via email to Universe Today. “Curiously, I have only so far seen wide field images of this nova, and none that actually show it’s very unusual strong pink colour.”

Why is it pink?

“The nova appears pink because we are really viewing the light from an expanding shell of ionized hydrogen which emits strongly in both the red and blue part of the optical spectrum,” Rolf explained. “These emissions give the nova its strong pinkish colour, similar to emission nebulae which are also predominantly pink/magenta in hue.”

A nova is the result of a thermonuclear explosion on the surface of a white dwarf star in a tight binary system. The white dwarf accretes matter from its nearby companion and eventually the pressure from nuclear fusion blows off the accreted layers from the surface of the white dwarf. Contrary to a supernova where the star itself is blown apart and ceases to exist, a nova does not result in the destruction of the host star. The white dwarf may continue to accrete matter from its companion and the process may repeat itself sometime in the future.

Read more: http://www.universetoday.com/107522/astrophoto-nova-centauri-2013-t...

[Carmen Elsa Irarragorri Wyland]

Ah, the Southern sky!

Yes, of course!

I have never seen it in this lifetime, but I dream of it all the time!

 

Thanks for the photos., this way I do not have t travel yet to the Southern Hemispehere!

(Even though I would not like something better than just do that)

[1yrns4vean19o]

Thanks Carmen! I have yet to see the southern sky either....let's take a trip :)

[Carmen Elsa Irarragorri Wyland]

I am with you on that one, Samael, it would be wonderful to see that skly, I dream of it so much!