Nova Delphini 2013 – a white dwarf with a yearn to burn

The bright nova in Delphinus photographed last night in a 16-inch telescope. Credit: John Chumack

It’s official. The new nova has been christened Nova Delphini 2013. Even better, it’s brightened since discovery. Last night a group of stargazers and I saw the pale yellow star with ease through the telescope. Later, when the moon had set, I was even able to spot the nova faintly with the naked eye at magnitude 5.8.

It’s been years since we’ve had an exploding star of this variety reach naked eye brightness. About¬†6-10 novae are discovered each year, most of them needing at least a small telescope to see. This year novae have popped off in Cepheus, Scorpius and possibly one in Aquila. Amateur astronomers are the nova finders, training cameras on swaths of the Milky Way night after night hoping to catch one in outburst.

The brightest nova ever recorded blew its top in Aquila the Eagle in 1918. V603 Aquilae shot all the up to -1.4 magnitude or nearly as bright as Sirius, the brightest star. You can still see it today in a 6-inch or larger telescope biding its time around magnitude 12 patiently waiting for another chance at nova-hood. Click HERE to get a finder chart.

The Milky Way is the favorite hunting ground for nova hunters. The dense concentration of stars along its band offers the best chance of finding the occasional nova. The galaxy averages about three dozen novae a year of which about a half dozen are discovered. Credit: Bob King

The Milky Way is the most lucrative hunting ground for novae hunting because stars are greatly concentrated along its length; that’s what creates the familiar hazy ribbon of light. You’re much more likely to spot one pointing your camera at millions of stars than at sparsely-strewn star fields outside the Milky Way band. Favorite hunting grounds include the Milky Way-streaked constellations of Scorpius, Sagittarius and Cygnus. I’ve never heard of one being found in the Big Dipper which is located well away from the galactic plane.

Novae occur in close binary systems where one star is a tiny but extremely compact white dwarf star. The dwarf pulls material into a disk around itself, some of which is funneled to the surface and ignites in a nova explosion. Credit: NASA

Just as there’s more than one type of tea, 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.

Just 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.

Looking more closely we discover that novae come in two basic types – fast and slow. Fast ones rise abruptly to maximum brightness, some of them vaulting 10 magnitudes a day. Their decline can be equally swift.

All-sky Milky Way mosaic photo compiled by the 2MASS survey in dust-penetrating infrared light shows the flat disk, home to younger stars and fast novae and the fat central bulge, where more slow novae and older stars are found. Click to full-size version. Credit: 2MASS, J. Carpenter, T.H. Jarrett and R. Hurt.

Slow novae behave as you might expect, sometimes taking several months to reach peak brightness and often lingering for months. Fast novae, which arise from more massive white dwarfs, are concentrated in our galaxy’s flat disk; slow ones from smaller dwarfs are found in the central bulge. I suspect this recent nova is the fast variety.

Nova Delphini is still in the fireball stage engulfed by incandescent hydrogen gas. Astronomers have spectroscopically measured the speed of the ejecta from the blast at 1,250 miles (2,000 km) per second.¬†That’s 4.5 million miles per hour. Think about that for a second. Now picture the scene in your mind’s eye when you see the nova for yourself.

This map shows Delphinus and Sagitta, both of which are near the bright star Altair at the bottom of the Summer Triangle. You can star hop from the top of Delphinus to the star 29 Vulpeculae and from there to the nova. Or you can point your binoculars midway between Eta Sagittae and 29 Vul. Numbers in gold are star magnitudes. Stellarium

I’ve included a fresh map above. The numbers in gold are star magnitudes to help you track the nova’s brightness as it brightens or fades in the coming nights. The larger the number, the fainter the star. Click HERE for a nice explanation of star magnitudes. For more maps, please see my earlier Universe Today post.

Update 8/16: Last night Aug. 15 I saw the nova at magnitude 4.8 and it was even brighter this morning. That means it’s nearly ten times brighter than at discovery a two days ago.

24 Responses

    1. Profile photo of astrobob

      Yes, many times. A couple years back it was near a naked eye star in Aquarius and that served as a great guide. I’ve also seen Vesta during good oppositions.

  1. Edward M. Boll

    If I read the almanac right, the Moon sets about 1:30 AM tomorrow. If the sky is clear I may go out after 1 AM , and try to spot this additional night point of light.

  2. Edward M. Boll

    I was thinking that we rarely ever get a comet that bright that is that well placed . Well on my third son’s 10th birthday, May 6, 2006, Comet 73P/ SW 3 was about as close as it was in 76 years and was excellently placed around magnitude 6. In one week it really moved across the sky.

  3. Pete

    Hi AstroBob, this is my first post to you. I am extremely interested in astronomy on quite a novice scale, partly due to owning a 6inch telescope, and I often find your articles very interesting and easy to understand. I want to find this nova using my telescope. Can you answer a few burning questions for me?
    1. Is this nova a southern hemisphere object?
    2. Are you a southern hemisphere observer? If so, that’s great, me too!!
    3. I can’t get my head around the fact the southern hemisphere won’t be able to see comet Ison in the evenings, because if it rounds the sun then everyone should be able to see it.

    Thank you for your time, Pete.

    1. Profile photo of astrobob

      Hi Pete,
      Glad to help.
      1. The nova is visible from the southern hemisphere. In central Australia for instance you’ll find it about 20-30 degrees high in the northern sky during the evening hours.
      2. I’m in the northern U.S. though I’ve had one opportunity to observe the sky south of the equator in Peru. You guys definitely have the edge on planets and the Milky Way.
      3. Comet ISON rounds the sun heading sharply north and soon becomes poorly placed for the southern hemisphere but well positioned for northern hemisphere viewers. If it were heading south instead, you’d have a better view over northerners.

  4. Pete

    Wow, thank you so much. Move to Australia will you, we need your internet presence in the southern hemisphere to help people like me. you are right, sometimes I don’t know where to look in the vast and bright southern hemisphere, I suppose you guys can have box seat for the comet then!

  5. Richard Keen

    Bob, the AAVSO light curve plotter has our Nova fading a half magnitude in the last few hours. Easy come, easy go – glad we caught it last night!
    Here’s the link – not sure if it will work with updates:

    1. Profile photo of astrobob

      Ah, so soon do they fade! I suspected this would be a fast nova. Still, novae can have plenty of fits and starts on the way up and down, so it will be fun to follow it.

      1. Richard Keen

        It’s fun tracking the Nova’s progress on the AAVSO site. It seems to have stabilized at magnitude 4.7, so who knows, maybe it will brighten up again! All the more reason to go out again tonight – and every night.
        Did you see Nova Cygni back in ’75? Now that was a fast nova – fast up, and fast down. No bumps or indecision on that one.

  6. Bob,

    First time poster. Just finished viewing (1:30 AM Rockport, MA) and it seemed pretty even with Vul 29 which is mag 4.8.

    Question which I cannot find out there. How many light years away is this nova? Always nice to know when the nova has actually occurred

    thanks, Paul.

    1. Profile photo of astrobob

      Hi Paul,
      Thanks for sharing your observation. I’m not sure anyone knows yet how far away. I’ve not seen a distance yet for it. Probably at least 1,000 light years as the progenitor star is very dim.

  7. Garrett

    Hi Bob,

    Nice article. Spotted it with the naked eye on two separate nights, once at peak brightness of magnitude ~4.5. Something I’ve been wondering is does anyone know what star this was from or will we find out once it starts to settle down?

    1. Profile photo of astrobob

      Hi Garrett,
      Cool you got to see it at max. That earlier blog was my attempt to explain what you were seeing. Essentially you’re witnessing a powerful explosion on the surface of a white dwarf star.

  8. Ignorant

    “In 1999, U.K. and U.S. astronomers independently reported finding evidence that one or more large planets or brown dwarfs gravitationally bound to our Sun, Sol may be perturbing the orbits of two different groups of long-period comets at the outer reaches of the Oort Cloud into the inner Solar System with the assistance of galactic tidal forces. Calculations in 1999 by John B. Murray of the United Kingdom focus on a smaller region centered around Constellation Delphinus at an estimated distance of 32,000 AUs (John B. Murray, 1999). The U.S. team (led by John J. Matese) most recently estimated that the substellar object (proposed to be named Tyche, the sister of Nemesis) may have a mass around one to four Jupiter-masses in the innermost region of the outer Oort Cloud, possibly orbiting Sol at around 10,000 to 30,000 AUs depending on its actual mass (Matese et al, 2010; and Lisa Grossman, Wired Science, November 29, 2010). While some astronomers have speculated that Matese and Murray are being misled by random statistical fluctuations or the past gravitational effects of passing stars, Matese believes that confirmation through direct observation can be achieved by NASA with its Wide-field Infrared Survey Explorer (WISE) satellite. On May 25, 2011, at the 218th American Astronomical Society Meeting, Ned (Edward L.) Wright, principal investigator of the WISE Mission, noted that Tyche might be detectable as a “possible low-mass brown [dwarf]” in observational data already collected by WISE (now being processed) if it has at least two Jupiter-masses (AAS presentation abstract by Lissauer et al, 2011; and John Matson, blog at Scientific American, May 27, 2011).”
    From: http://www.solstation.com/stars/oort.htm

    1. Profile photo of astrobob

      To date no brown dwarfs or large planets have been found either by ground-based or WISE observations at solar system distances. That doesn’t mean nothing’s out there, but there is no evidence … yet.

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