Nova Delphini 2013

Nova Delphini 2013 was discovered on August 14th in 2013, peaked two days later at magnitude 4.4, and by November 10th was down to magnitude 11.2. It has been quite red. See this preliminary light curve from the AAVSO.
Nova discovered in Delphinus August 14, 2013
The new nova is in the northwest corner of Delphinus, near the border with Sagitta and Vulpecula. Click on the image above for a full-page printable PDF.
Sky & Telescope
The field of the nova is easy to locate north of the familiar star pattern of Delphinus. To its west, Sagitta, the Arrow, points toward it.

Use the chart at right, or sky chart, which is a slightly modified version of page 64 from Sky & Telescope's Pocket Sky Atlas.

Here's a 10°-wide comparison-star chart from the American Association of Variable Star Observers (AAVSO). The nova is the cross at center. As the nova dims, make an appropriate new chart with the comparison-chart maker starting on the a href="" target="new_window">AAVSO home page. The AAVSO's comparison-star magnitudes are the ones to use, so that everyone's estimates will be made consistently.

Nova Delphini 2013 on morning of Aug 16th
S&T: Dennis di Cicco

Discovery of Nova Delphini 2013

The nova was discovered by Koichi Itagaki of Yamagata, Japan, in an image taken at 14hh Universal Time (2 p.m. EDT) on August 14th. It was not present in a photo that he took the previous day. Here is the announcement from the IAU's Central Bureau for Astronomical Telegrams. Nova Delphini 2013 was apparently 17th magnitude before erupting, so it brightened roughly 100,000-fold to its peak on August 16th.

What Is A Nova?

A classical nova happens in a special kind of tightly-orbiting binary star system: one where a relatively normal star pours a stream of hydrogen onto the surface of a companion white dwarf. When the layer of fresh hydrogen on the white dwarf's surface grows thick and dense enough, the bottom of the layer explodes in a runaway hydrogen-fusion reaction — a hydrogen bomb in the shape of a thin shell roughly the size of Earth. The underlying white dwarf remains intact, and as new hydrogen builds up, the process may repeat in a few years to tens of thousands of years.

37 thoughts on “Nova Delphini 2013

  1. Taras Wertelecki

    Despite milky and light polluted skies in my local area, I quickly located the nova once I found NGC-6905 with a 10-inch Dob. When I checked my Sky & Telescope Pocket Sky Atlas, the nova immediately stood out. It appears to be brighter than 6th magnitude, I thought I might have glimpsed it with the unaided eye. Through the 10-inch with a 24mm Explore Scientific 82 degree eyepiece, the planetary nebula and nova fit nicely into the field of view, the nova shining a somewhat yellowish white in color. Normally I do not look for novae, since most are faint but this one is very obvious in any small telescope or pair of binoculars, and well worth the effort to look at.

  2. Babak Tafreshi

    Thanks for the timely post Tony. Just looked at my images from Aug. 14 morning, around 4:00 UT, nearly 14 hours before the discovery, and I see NO sign of the nova down to magnitude 9, as far I can easily detect in the wide-field shots.

  3. Peter

    It’s a silly story, but now I have to post it. 11 hours prior to discovery, (I think!) at 10 pm PST, my son and I were out looking for meteors. We’re in central Seattle, facing northeast, and I saw no meteors in our light polluted skies. But I did comment on a flash of blue light to the east that I caught out of the corner of my eye. it was quick but bright, getting about ask bright as Vega. There was no movement. My assumption was that my eye caught some portion of a meteor, but I’m a longtime sky watcher and the event was weird enough that I tried to rule out other causes– a flash of reflected light from a satellite for example. I only have my star maps to suggest that it occurred in roughly the right place. However, I assume there were thousands of people out looking for meteors and that many others would have seen what I saw. Can the initial blast of a nova appear and disappear so quickly? At any rate, in case, if I am one of thousands, I figured I’d report it. Bat me down gently, please!

  4. Gabriel Murawski

    I couldn’t find Nova on my photos taken 24 hours before it reached 6.5 mag. It was fainter than 10.2 mag. at that time, so it rapidly grow up. I can’t wait to see this Nova Star on this night.

  5. Frank ReedFrank Reed

    Hi Peter, You reported observing a "bright flash" some 11 hours prior to discovery of the nova. Quick brilliant flashes like this have not been confirmed in association with real novae, and they wouldn’t make much sense in terms of the theoretical models that we have of how novae work. You can probably rule out any connection. You yourself proposed a very probable explanation for what you saw: "a flash of reflected light from a satellite". If you can pin down the time and the direction in the sky a little better, it might even be possible to make a reasonable guess about which satellite produced the flash. You had implied that you ruled out this possibility (maybe by checking for Iridium flashes?), but only a small fraction of flaring satellite have predictable flashes so there’s no practical way to rule this out. I have seen quite a few of these unpredicted satellite flares over the years, and they can be quite impressive. I would bet good money that’s what you saw! 🙂

  6. Eric

    Another possibility for what you saw was an Earthgrazer from the Perseids. Based on the time Perseus was just rising above the northeastern horizon. Did it appear to move up from the horizon? if so you may have caught yourself a meteor skimming our atmosphere.

  7. Mircea Pteancu

    I found out today about Nova Del 2013 from a colleague on ”60mmtelescopeclub” and quickly forwarded the info to our Romanian forum.
    As a result,until now,the Nova Del was observed by my friend Silviu Constantinescu aka zoth ,using a Kronos 7x50mm binocular and a 90x600mm RFT refractor.
    I was also successful in observing the Nova Del ,using my Fujinon Mariner 7x50mm and my Optus 76x700mm Newtonian.
    Using two comparison stars of 4.8mv and 5.7 mv,I derived for 15 August, at 21:00 UT , a brightness of 4.98 mv.
    The comparison star of 4.8 mv was very dim but visible with naked eyes.I believ I noticed also the Nova Del 2013 with naked eyes but only with averted vision.
    I need to add,I’m not a trained variable star observer so please take my magnitude estimations with a grain of salt.
    Clear sky,Mircea

  8. Clay Sherrod, ASO

    Magnitude, astrometric position and CCD photometry from Arkansas Sky Observatories
    0.51m f/4.9 DK Astrograph.

    C2013 08 15.24387 PNV20 23 30.65 +20 46 02.9
    06.29 R H45

    Dr. P. Clay Sherrod
    Arkansas Sky Observatories
    MPC H45 – Petit Jean Mountain South
    MPC H41 – Petit Jean Mountain
    MPC H43 – Conway West

  9. Peter

    Hey, thanks for your responses about my own personal nova! Yes, "ruling out" wasn’t the right word– "considered" would have been better! But I’ve kept reading about novae today, and I realize there wouldn’t have been a sudden flash. What I saw was quite bright, but immediately disappeared. A reflected flash off a satellite makes good sense, or perhaps my peripheral vision caught part of a meteor trail. What I saw didn’t move, at least in my perception, but it was bright– like Vega appearing and disappearing in a blink. I’m waiting for a clear night to see exactly where it happened, since the window between trees and rooftops is pretty small. Anyway, thanks again– twas fun will it lasted!

  10. bob frybarger

    A meteor on a trajectory coming straight at you would not move on the sky.It would appear as a flash. I would love to think that you saw the begining of the nova however…

  11. Phil Creed

    Quick-strike, "guerrilla astronomy" tactics were used to catch Nova Del in the 1:05 – 1:10 a.m. EDT time frame. The nova was visible to the naked-eye at 1:10 a.m., just prior to the clouds covering it up. Estimated brightness at that time (Aug. 16.215 UTC) was about 4.8, on par with 29 Vulpeculae.

  12. Dave-MitskyDave Mitsky

    Nova Delphini 2013 was very easy to see through my Celestron 8x42s shortly after 1:00 a.m. EDT. It seemed to be just a bit less bright than nearby 29 Vulpeculae (magnitude 4.8).

  13. Mark Looper

    Looking through hazy "sucker holes" between clouds, which is about the best I can expect here on the windward side of Oahu, at 3 a.m. 8/16 EDT (9 p.m. 8/15 local time), the main figures of Delphinus and Sagitta were barely naked-eye visible, so limiting magnitude was about 4.0 or so. The nova was easily visible in my quarter-century-old Minolta 8×40 binocs; I concur with Phil Creed and Dave Mitsky that it was about as bright as 29 Vul, and there were no brighter stars closer to it. I’ll find it easy to keep track of it as it fades, between the double (HD194577) to its upper left in the chart above and the little asterism to its lower left, straddling the 20-degree declination line. It looks to me like a little Aquila with the head turned right instead of left, with HD194841 as Altair and HD194616 and HD195479 at the wingtips. The "Eaglet"?

  14. Wheeler Huneycutt

    Saw this last night naked eye just north of Tucson at 4am (1100GMT 2013/8/16). In 8×40 binoculars it was about the same magnitude as 29 Vul (Mag ~ 4.8)

  15. Frank ReedFrank Reed

    The distance can be estimated very roughly from the fact that all common novae are believed to have the same absolute magnitude at various phases (within some range). In other words, they qualify as "standard candles" though not very good standard candles. Based on its peak magnitude, and assuming it has in fact peaked, the distance is probably somewhere in the range from 2500 to 5000 lightyears. Very likely the distance is of that order of magnitude –you can almost certainly rule out distances less than 1000 ly and greater than 10,000 ly. To put it in useful backyard observing terms, this nova is about the same distance as Deneb or somewhat further away.

  16. Harry Hamill

    I observed around 20 Perseids on the night of the 12th-13th August. Among these were a couple of spectacular fireballs leaving long and persistent trails. There were also a couple of extremely short ones. One was identifiable as a Perseid from the short but discernible track but the other was so brief as to be simply ‘a bright flash’. I am pretty certain though that it was just a meteor with a very brief track and would suggest that Peter’s observation was of a similar event.
    Oddly enough I also observed an IRIDIUM (IRIDIUM 69) event visible at around 10. 25 BST from Chelveston, Northamptonshire UK. The flash was extended over about three seconds, quite unlike the meteor.

  17. Frank ReedFrank Reed

    I do recommend this one for casual stargazers (with some experience using binoculars at night). If you can find Delphinus, next locate the brighter stars of Sagitta. Draw a line down the length of Sagitta in the direction of "flight" (of the arrow) and you’ll be right there. Right now the nova is the brightness little star in that patch of sky, so you really can’t miss it. There’s nothing much to it –it’s just a star that shouldn’t be there, but there’s that pleasure in knowing that you’re observing a colossal explosion thousands of lightyears away… As of a few minutes ago, I would estimate its brightness at magnitude 4.8. That’s less than the peak brightness from about twelve hours ago, so it looks like it’s downhill from here…

  18. Michael Boschat

    Nova Delphini from Halifax. I used my 7×50’s and gave an estimate of 4.8, using the stars numbered on the AAVSO star map. I could **just*** see it with adverted vision again.

  19. charley Langley

    1. 20130817 /2 0133 MDT (0733 UT
    2. sky thin clouds. visibility M2.5 alpha, beta, gamma, delta, epsilon in Cygnus. Moderate light pollution. At this site I can usually see down to M350 on a good night.
    3. Using 10X50 Bushnell FALCON binoculars and the Sky and Telescope I was able to find the Nova. I looked for the mid point between beta CYG and alpha AQI (Altair) which allowed the identification of the constellation SAGITTA (The arrow). Scanning beyond gamma SGE the sky angle of SAGITTA located a relatively bright star (compared w/ surrounding stars).
    4. This star was:
    a. brighter than gamma Sge @ M350
    b. dimmer than alpha Aquilla (Altair) @ M075
    c. dimmer than gamma Al @ M270.
    5. My bald face guess would be M30 (Magnitude 3.0) at this time.
    6. Time of observation was 0133 MDT. Given a 6 hour off set from Greenwich that gives 0733 UT.

    Reguardless of how correct my observations were, this was quite a thrill. It is the first time that I have observed a Nova.
    Charley Langley

  20. Charley Langley

    I looked my notes over and found to my dismay that several items of importance had been left out and some of the language was far from clear; following should more readable. CCL Jr.

    From: "Charley Langley"

  21. Andrew

    From 100 miles east of Seattle, on the dry and darker side of the mountains, at about the same time I saw the bright flash Peter reported. I had just sat down to watch the Perseids and thought the evening was off to a great start. Never thou

  22. Michael-MartinMike Martin

    I’m fascinated by all of the Contributors and their intelligent and informative posts on Nova Delphi.with Waxing Gibbous Moon and the nighttime cloudy skies over the last few days, my observations had the be postponed.As a novice I have two questions.
    First off, does anyone know long the Nova will stay at an observable magnitude and so what will it be when Moon is waning in order to vies at optimal conditions.
    Second, I hope I’m right when I say this was a Binary Star. And if so is there any way of knowing the size and name of the Host Star and its white dwarf companion.
    Thanks everyone and Clear Skies and Great Views
    Mike Martin

  23. Frank ReedFrank Reed

    Mike Martin, common (or "classical") novae like this one can have variable light curves, and there may well be spikes in brightness ahead but you can expect a drop in brightness of a magnitude in a week very roughly. So it may (repeat MAY) be tough to find in binoculars a month from now. But don’t let the bright Moon stop you this week! You can still easily estimate its magnitude even with all that light in the sky since this is still close to naked-eye brightness. You asked for confirmation that this was a binary star. Yes. Almost certainly. That is believed to be the origin of all common novae : a large star, typically a giant or supergiant, in a tight orbit with a white dwarf star, shedding mass onto the white dwarf until that ignites much like a hydrogen bomb. The article here in fact explains the rest quite clearly. As for the size of the larger star, we can only guess at this time. Later analysis may provide some details. It’s quite possible that there is some pre-nova data available. As for its "name", it is relatively unlikely that it had any kind of catalog designation, let alone a name, before it went nova. This was a faint star, a few thousand lightyears away, in an extremely rich star field. It is possible that it was never catalogued before. It certainly has a few names now: it’s "Nova Delphini 2013". Or if you like your names a little more tech-sounding, you can call it "PNV J20233073+2046041". Not exactly euphonic! 🙂

  24. Michael-MartinMike Matin

    Thanks Frank for the valuable info. OK Novice learning time. With the Moon full tonight almost right below Delphinus. Is it possible to use Binos or a Scope. I have the current coordinates from AAVSO. And last Question.what does Anyone think the original magnitude of the white dwarf before it went Nova.

    Thanks All and Clear Skies

  25. Frank ReedFrank Reed

    Mike, sure! Go out and look tonight. I saw it about an hour ago. The Moon will obviously make the sky brighter, and that means less contrast. You’ll certainly see fewer really faint stars near the nova, and it’s definitely fading. But it’s still around magnitude 5.7, and stars that bright can be observed even within a few degrees of the Full Moon. As for the brightness of the white dwarf before it went nova, that’s a little tough because the star itself would have an accretion disk around it much brighter than the white dwarf star in isolation. But let’s consider an average white dwarf without its accretion disk. Most range range in absolute magnitude from about +7 to +13. Let’s go with +10. By definition the absolute magnitude is the same as the apparent magnitude when the star is at a standard distance of 10 parsecs away. This star is (very roughly!!) a thousand parsecs away. That’s 100x further than the standard distance. Each factor of 10 in distance decreases a star’s brightness by a factor of 100 (inverse-square law) which is 5 magnitudes so that means a total of 10 magnitudes fainter implying a pre-explosion magnitude of just about +20. In addition you can expect several magnitudes of absorption so perhaps +23 for the original visual magnitude. The companion star would have been much brighter, easily as bright as magnitude 15. But it’s too early to say.

  26. Paul Kobetz

    We have been imaging the Nova since 8/16/2013.. it had brightened from 6 to 4.5 and now on 8/19/2013 it appears to be dimming down to 6.3. Imaging at Rubicon Observatory, Ukiah, Ca CDK17 0.4m; camera STL11. Imaging note, differences notes as to the level of magnitude when calibrating the Nova due to saturation or linear region of the camera… it was easily overloaded by this amazingly bright object. What a treat!

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