The M82 supernova is at peak brightness: How to see it
By Brian Dodson
January 31, 2014
A cloudy night in London led to the discovery of the 21st Century's brightest supernova to date. The new supernova 2014J, the brightest since 1993, is located in the galaxy M82. This Type-Ia supernova has just reached its peak brightness of magnitude 10.6. M82 lies at a distance of only about 12 million light years, which explains the brightness of 2014J in our skies. 2014J is bright enough to be seen in small telescopes or perhaps in (very) large binoculars. We'll tell you how to find it.
On the night of January 21, 2014, a group of astronomy students at University College London were scheduled to learn how to use a campus telescope as part of a practical astronomy class. The telescope is a Celestron C14, a 14 inch (355 mm) catadioptric telescope which is normally considered an upper-end amateur scope.
Noticing that clouds were rapidly closing in, The instructor, teaching fellow Dr. Steve Fossey, decided to scrub the formal introduction and simply show the students how a CCD camera is used to image a celestial object. The students chose M82, a galaxy which is a well-known showpiece in the northern skies. Ten minutes later, the group had discovered the new supernova. The photo above shows M82 prior to the supernova on the left, and a photo taken after the supernova appeared on the right.
Astronomers the world over quickly recorded spectral information that showed 2014J to be a Type-Ia supernova. This is a supernova that results when a white dwarf star in a binary stellar system continually collects additional material from its partner. The usual type of white dwarf is a star that has completely fused its stocks of hydrogen and helium. As a result, the white dwarf is mainly composed of carbon and oxygen.
Carbon-oxygen white dwarf stars must have a mass smaller than 1.44 solar masses, after which they are no longer able to support their own mass, and collapse into a neutron star. Before they reach this point, however, the increased pressure and temperature at the core is thought to trigger fusion of the carbon and oxygen, resulting in the very rapid conversion of a few parts in 10,000 of the mass of the white dwarf into energy. It is this energy that powers the supernova.
Spectra taken of 2014J show distinct reddening of the light coming therefrom, indicating that the light is being scattered by interstellar and intergalactic dust, losing about two magnitudes of brightness in the process. Still, we are left with a magnitude 10.6 supernova to look at, an enticing prospect for amateur astronomers north of the Equator. (M82 is in the far northern skies, so observing the supernova becomes more and more difficult to the south.)
M82 itself is a rather bright (magnitude 8.4) irregularly shaped galaxy, about eight times brighter than 2014J. It is intrinsically some five times brighter than the Milky Way galaxy, even though it has only one-twenty-fifth of the Milky Way's mass. It is a starburst galaxy, so named because it is undergoing a phase in which star formation is taking place at an extremely rapid rate.
This is likely the result of a close encounter within the past few hundred million years with its larger neighbor galaxy M81 (magnitude 6.9, about two-thirds of a degree south of M82). In the process, a great deal of interstellar gas was transferred into M82, and also gas transport within the smaller galaxy increased considerably, thereby driving the very rapid rate of star birth observed today.
If you have a telescope with an aperture larger than 6 inches (150 mm), seeing the new supernova will be relatively easy from any reasonable observing site. But how can you get a look at Supernova 2014J in small scopes?
What about binoculars?I'm assuming that you are observing in dark skies, and are not expert in viewing stars and nebulae. Although M81 can be seen even in the smallest binoculars, M82 is a bit more elusive. Based on numerous reports, it seems likely that M82 won't be visible in any binoculars you are likely to have hanging around the house – 15x70 binos seem to be the smallest size at which most people can see M82. There are tricks, such as using averted vision and moving the field, but learning these in the next couple of days would be difficult.
Similarly, Supernova 2014J should barely be visible in 15x70 binoculars. Also, at this level of magnification a mount of some type will be needed to hold your binoculars steady. If you happen to have a pair of 20x80 or larger binoculars, go ahead and try, but anything smaller will be a crap shoot.
Part of the reason binoculars have trouble seeing both M82 and 2014J is that they brighten the background light of the sky as well as the objects you want to observe. The apparent intensity of the background light fades as the magnification increases, so that for this game telescopes have an extra card to play. Keep in mind, however, that the surface brightness of M82 will also decrease with magnification, so a balance will have to be set to see both objects at once.
To illustrate this, a four-inch (100 mm) telescope used at its lowest effective power of 15 will allow novice observers to barely see a magnitude 11 star. While this is sufficient to see 2014J, one wouldn't be positive that a star was there. In contrast, if you use 100 power, the limiting magnitude is more like 12.5, meaning that you can see stars about two magnitudes fainter than the supernova. Turning that around, the supernova would appear like a magnitude four star does to your unaided eye. (The dimmer stars in the Little Dipper are about fourth magnitude.)
What size scope?So what size scope is likely to succeed? Nearly any size telescope will suffice to see the supernova. Even a 60 mm (2.4 in) scope operating at 100 power will allow an observer to glimpse it in dark skies and with well-dark-adjusted eyes. The trick will be to tell which star is the object of interest, as this telescope may not show M82 at this magnification. It is likely that a four-inch (100 mm) scope at a magnification of about 50 will reveal both M82 and the supernova. This magnification will also provide a field of view of about a degree, which is useful as it allows both M81 and M82 to be visible, thereby giving another landmark with which to identify 2014J.
Having looked at suitable instruments, let's discuss how to go about observing this object, which is rather difficult for small telescopes. We are fortunate that today is New Moon; for the first few days of February the Moon will set before midnight.
Location, location, locationOnce you have chosen a time, the most important choice is to find an observing location well away from any lights. This means rural locations in most of the US and Europe. Suitable locations will be easier to find north of a city or town than south: If you are south of a city, you will be looking at M82 through the scattered lights of the city. Pristine skies are not needed, but good observation sites for 2014J are probably going to be 5-20 miles (8-32 km) – less if you live in an isolated small town, more if you live in a major city – further outside your town or city than anything reasonably called suburbia.
The second requirement is that you let your eyes adjust to the dark for a good half an hour before seriously looking for the supernova. You will be able to find the M81/82 galaxy pair long before you might see 2014J. Dark does not mean driving in the dark, or reading charts or moving around using a flashlight (unless it has a red filter.) It means sitting down somewhere and letting the skies open to your improving night vision.
How to find it
Here's how you find Supernova 2014J. First, find the Big Dipper in Ursa Major (figure above.) If you follow a path between the two stars of the bowl indicated by an arrow in the figure, and extend that path by another equal interval in the same direction (second arrow), the tip of the second arrow will be slightly south of M81 and M82. M81 will be easily visible in binoculars and small telescopes set to their lowest magnification (preferably 15-25 power).
If you don't see the fuzzy blob of M81 at first, sweep the area slowly with the scope. If you get lost, start over. As it is difficult to miss M81 in binoculars, you might want to use them to get familiar with the surroundings of M81 prior to finding it in your telescope.
Once you have M81 in the field of view of your telescope, take a look about two-thirds of a degree north to see if you can see M82. (If your scope is set for 20 power, the field of view will be roughly 2-3 degrees in size.) Even if you don't see it, center the scope on M81, and switch eyepieces to obtain a magnification of about 50. This makes your field of view about a degree in size.
Now place M81 at the south end of the field of view, so that you are looking at roughly the same region shown in the finder chart below. On the left and center is a finder chart I prepared, while on the right is a NASA astrophoto of the same region. The finder chart shows stars to 12th magnitude, while much fainter stars appear in the astrophoto.
The technique with which to hunt down the supernova is called star hopping. On the chart above you will see that the brightest star in the field is about two-thirds of the way from M81 to M82. The star is magnitude 9.35, and will be quite easy to see in the smallest telescope.
About 15 minutes of arc north and slightly east of this star appears a line of three stars which angles a bit more to the east. At 12th magnitude, you will likely not see the first of these stars, but the second is of magnitude 10.6 (the same as 2014J), and the third is a tenth magnitude star, which should be reasonably easy to see. Supernova 2014J is located about 2.5 minutes of arc further along that same line, slightly less than the separation between the second and third stars in the line.
Finding Supernova 2014J with a telescope 6 inches (150 mm) or smaller in aperture is likely to be a bit of a challenge for a novice observer, but the reward in seeing one of the largest explosions in the Universe by eyesight is immense. Given that supernovae this bright only appear every couple of decades, I urge you to go out and see what you find – and sooner rather than later. The supernova is currently at peak brightness and will be much harder to see in just a week. Not only do Type-Ia supernovae fade more rapidly than any other type, but the waxing moon will begin to cause problems after about February 5th or 6th.
Source: University of London Observatory