New Nova Sagittarii 2012 #4 is located just above the star Delta in the “spout” of the Teapot constellation of Sagittarius. Sagittarius is east or left of the Scorpion with its bright fiery star Antares. The map shows the sky facing south around 11:15 p.m. Maps created with Stellarium.
Novas are popping up like daisies in the constellation Sagittarius this year. To date, four “new stars” have been discovered in the Teapot, enough to keep its contents at a steady boil.
Earlier yesterday (July 7) Koichi Nishiyama and Fujio Kabashima of Japan found the most recent nova – Nova Sagittarii 2012 #4 – on exposures made with a camera and 105 mm lens. Shining at magnitude 7.7 at the time of discovery, the nova was bright enough to see in binoculars and small telescopes. It still is. Last night I saw it from my driveway at the identical brightness through my 8x40s.
Use this zoomed-in map with a pair of binoculars or small telescope to hunt down the new nova. Center your scope on the naked-eye star Delta in Sagittarius, then move about 1 degree north to find a bright triangle of 6th magnitude stars. Nova Sgr #4 is about 1/2 further north just south of the magnitude 7.2 star.
Typical 40mm and larger binoculars can reach 8th magnitude or fainter; with a good locator map, you should be able to see the nova for yourself in the coming nights, especially since the moon is rapidly departing the evening sky.
As we learned a few days ago in the case of Nova Persei, novas occur in close binary stars, where a small but extremely dense and massive (for its size) white dwarf grabs hydrogen gas from its closely orbiting companion. The gas swirls down to the dwarf’s 150,000 degree F surface, where it’s compacted by the gravity and heated until detonating like a gazillion thermonuclear bombs. Suddenly, a faint star that wasn’t on anyone’s radar vaults a dozen magnitudes to become a standout “new star”, one bright enough for a pair of Japanese amateurs to snag it in a 40-second exposure.
Model of a nova in the making. A white dwarf star pulls matter from its bloated red giant companion into a whirling disk. Material funnels to the surface where it later explodes. Credit: NASA/CXC/M. Weiss
Novae can rise in brightness from 7 to 16 magnitudes, the equivalent of 50,000 to 100,000 times brighter than the sun, in just a few days. Meanwhile the gas they expel in the blast travels away from the binary at up to 2,000 miles per second. This is one big firecracker!
Depending on the particulars of the explosion, including distance and whether or not there’s a significant amount cosmic dust between us and the star, novae can be bright or faint.
Some, like Nova Cygni 1975 (in the Northern Cross) reached magnitude 1.7 in late August that year. I remember how its presence “distorted” the outline of that familiar constellation. Other novae are too faint for small instruments or brighten and fade so quickly, if there’s a cloudy spell, you might miss it.
An imaginary view of a nova explosive seen close up. The blast is not powerful enough to eject the companion star. Credit: Emanuele Feronato, Bob King
Sagittarius – and nearby Scorpius and Ophiuchus also – are familiar discovery grounds for novae because that’s where most of the stars of the Milky Way are concentrated. Why? Because we’re facing the center of the galaxy when we direct our gaze toward these star groups. The more stars in your line of sight, the better the chance that one of the many billions will flare into nova-hood.
The best time to see Nova Sgr 2012 #4 is between about 10:30 p.m. and 3 a.m. Optimum time is around midnight when Sagittarius, always low in the southern sky from northern latitudes, reaches its highest point above the horizon. Use the maps to star-step your way to the nova. For those familiar with celestial coordinates, its exact position is: R.A. 18 h 20′ 27.3″, Dec. -27 degrees 44′ 26″.
You can also get a nice printable chart at the American Association of Variable Star Observers (AAVSO) website. In the Star Finder box, type in PNV J18202726-2744263, the temporary name for the new nova, and click the Create a finder chart link. Your chart will have north at top. If you want to print out a different orientation or a more customized version, just click the blue Return and Replot link.
How bright the nova will be tonight is anybody’s guess. Maybe the same as last night, but it could also be fainter or brighter. Good luck spotting one of nature’s more explosive creatures!
Hi Bob,
The clearing sky last night caught me off guard. I made use of it to check
any obstructions of Sagittarius by my southerly trees in preparation.
I plan on losing some sleep tonight (7/10) to image the nova. If I all goes well (my
southern sky is kind of bright) I’ll send you a pic!
Clear skies,
Bill in Massachusetts
Hi Bill,
I hope it’s clear for you tonight. Please do send a pic – I’d love to use when I update the nova’s activity in the blog tomorrow. Its H-alpha emission is on the increase which means it might start showing a reddish color on your exposures. Good luck!
Good morning Bob,
Clouds were a problem again last night. A beautiful clear spot opened around
1130hrs local time so I lugged the equipment out with high hopes, even though
radar showed I was in a hole, so the clear sky wasn’t going to last.
I’m a die-hard star hopper, a boast that’s getting a little “old” as my 62 year-old-body gets a little older! The point being, if I could have just punched in coordinates and started shooting, I may have been showing you an image today.
I also thought I had my star maps in order but got disoriented right off, slowing the process. New maps are in order for tonight. “Lost in Space” made a good TV show, but is a sad experience to a seasoned observer!!
Images were made of the field I had in the scope (about a half degree from the nova, it turns out) and it is clear that the nova will show up easily once I get my act together.
One more excuse: I had a 12 to 15 degree window between two southerly trees
through which to observe! Boy, does the Earth turn fast under these conditions!
Finally, the clouds arrived.
“From time to time, while looking at the moon, clouds come
to give rest.” – Chinese Proverb
We’ll see what happens tonight.
Bill in Massachusetts
Hi Bill,
Things like this happen to all of us. Sounds like you’ve got a good sense of humor. The nova will be there tonight, too. Last night it was still fairly bright at magnitude 8.4. Love the Chinese proverb.
Hi Bob,
Totally clouded out last night (7/11). Thought for sure I would bag it with my
newly generated maps and a tweak of my finder aim.
I’m not going to jinx myself by revealing tonight’s plan.
Did you get a mag estimate last night?
Bill
Hi Bill,
Holding steady at 8.4 magnitude last night. Good luck tonight.
Hi Bob,
I know you’re busy with the fantastic auroral displays happening in your sky.
Incredible images!!
I’m experimenting sending images to you. This is the Nova caught on 7/12-13.
You probably recognize the star field (if the images show). No. 4 is near the center.
I’ll keep experimenting if the images don’t show.
[IMG]http://imageshack.us/a/img96/8484/novano4sagittsqarecropd.jpg[/IMG]
This is just before the tree blocked me and ended observing.
[IMG]http://imageshack.us/a/img266/9370/novano4saggittreesdsc00.jpg[/IMG]
Hi Bill,
Great – you got it dead center. Thanks for sending. I’ll try to use one when I do my next update.
Thanks Bob! I got worried because I couldn’t see the images on my screen.
The shots were taken through a 152mm Antares refractor afocally with a 40mm
eyepiece. The camera is, conforming to my unconventional ways, a Sony DSC F-707,
30 seconds @ ISO400. Tungsten white balance to counteract the heavy orange cast light pollution. Orion EQG mount. Single frames, no stacking.
The background sky (color and brightness) is as it appeared to the naked eye.
Good luck with the aurora tonight!
Bill
Good morning Bob,
I hope you got to see SOME aurorae last night. It looked like it wasn’t going
to reach over New England and was subsiding, so I crashed. Very bright hazy sky
for me anyway.
I was fooling around with PS and was so proud I figured out how to imbed an arrow in my nova No. 4 image that I’m sending it to you. It’s just that I don’t know many people who would appreciate such a thing!
Congrats again on your wonderful aurora imagery!!
Bill
[IMG]http://imageshack.us/a/img84/8963/novano4sagittsqarearrow.jpg[/IMG]
Hi Bill,
Thanks for the congrats! I saw the nova last night at mag. 9.0. Will update tomorrow. Super busy at the moment.
Received. I understand, Bob. I was a photojournalist and columnist for well over 20 years.
Bill