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Friday, 31 January 2014

Supernova in M82 Peaks

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Alan MacRobert
OBSERVING BLOG by Alan MacRobert

Supernova in M82 Reaches Its Peak

Supernova 2014J in M82 has finally stopped brightening, at about magnitude 10.5. The galaxy and supernova are visible in amateur telescopes in the northeast during evening.

Last updated January 31st

Supernova in Messier 82
The supernova in M82 as imaged by Leonid Elenin (Lyubertsy, Russia) and I. Molotov (Moscow, Russia) on Jan. 22.396. It's located at right ascension 9h 55m 42.2s, declination +69° 40′ 26″. It was V magnitude 11.7 at the time.
Leonid Elenin
On January 21st a group of astronomy students spotted a supernova in M82, the famous nearby irregular galaxy in Ursa Major. It continues to swell, becoming easier to see in smaller and smaller telescopes, and now seems to be peaking at about V magnitude 10.5 (as of January 31st). Here's a preliminary light curve, right up to date, from the American Association of Variable Star Observers (AAVSO). The supernova is still showing its same orange tint due to reddening by dust within M82.

Shortly after its discovery, Yi Cao and colleagues at Caltech took a spectrum that suggested it was two weeks away from reaching its peak brightness in the first few days of February. This and other spectra showed it to be a Type Ia supernova — an exploded white dwarf — with debris expanding at up to 20,000 kilometers per second. Because it appears reddened, it must also be dimmed by dust along our line of sight. By one estimate, it would be two magnitudes brighter if we were seeing it in the clear.

Supernova in Messier 82
Before and after. The supernova image, taken remotely by Ernesto Guido, Nick Howes, and Martino Nicolini on January 22.3, shows the exploded star at unfiltered CCD magnitude 11.3. Their website.
Ernesto Guido / Nick Howes / Martino Nicolini
M82 is a near neighbor as galaxies go, at a distance of 11 or 12 million light-years. It's a favorite for amateur astronomers and researchers alike with its thick dust bands, sprays of hydrogen gas, and bright center undergoing massive star formation. The supernova is not in the central star-forming region but off to one side, 58 arcseconds to the west-southwest.

Remarkably, the supernova went undiscovered for nearly a week as it brightened. Prediscovery unfiltered CCD images by Koichi Itagaki of Yamagata, Japan, show nothing at its location to as faint as magnitude 17.0 through January 14.5. But it was magnitude 14.4 on January 15.6, 13.9 on January 16th, 13.3 on January 17th, 12.2 on January 19th, and 11.9 on January 20th. (Images.) So the actual explosion occurred (from Earth's viewpoint) late on January 14th or early on the 15th Universal Time.

It received the name Supernova 2014J once its nature was confirmed. It originally went by the preliminary designation PSN J09554214+6940260.

The M81-M82 galaxy pair, 23° apart, lie in a dim region of Ursa Major off the Big Dipper. They're detectable in a large finderscope in a dark sky. Once you've recognized the general area, you'll probably need this more detailed finder chart.
Sky & Telescope diagram
Where to Look

M82 is well up in the northeast by 7 or 8 p.m. (for observers at mid-northern latitudes). The waxing crescent Moon begins to light the evening sky noticeably after about February 2nd or 3rd, so don't wait.

Here's a comparison-star chart from the AAVSO. On the chart north is up, east is left, and the field is ½° wide; star magnitudes are given to the nearest tenth with the decimal point omitted. The galaxy shows up as an elongated swarm of faint dots. (If you want other parameters, you can make your own chart using the AAVSO Variable Star Plotter; for star name enter SN 2014J.)

Here's the preliminary AAVSO light curve with photometry in the B, V, and R bands (blue, "visual," and red light) as well as eyeball estimates (shown black). So far the light curve is developing just as expected for a reddened Type Ia supernova.

Italian observer Gianluca Masi hosted an online supernova-imaging session with his Virtual Telescope Project on January 25th. Click on the link to see a replay of the hour-long event.

Here's a wide-field view of M81 and M82 including the supernova, for a broader perspective.

Supernova in M82
S&T senior editor Dennis di Cicco captured M82's supernova on the evening of January 23rd with an Officina Stellare 12-inch f/7.9 RiDK 305 astrograph.
S&T: Dennis di Cicco & Sean Walker

A Flukey Find

The first people to recognize the supernova were a group of students — Ben Cooke, Tom Wright, Matthew Wilde and Guy Pollack, assisted by teaching fellow Stephen J. Fossey — taking a quick image at the University of London Observatory (within the London city limits!) on the evening of January 21st at 19:20 UT.

"The discovery was a fluke," says a university press release,

—a 10-minute telescope workshop for undergraduate students that led to a global scramble to acquire confirming images and spectra.

"The weather was closing in, with increasing cloud," Fossey says. "So instead of the planned practical astronomy class, I gave the students an introductory demonstration of how to use the CCD camera on one of the observatory’s automated 0.35-meter telescopes."

The students chose M82, a bright and photogenic galaxy, as their target, as it was in one of the shrinking patches of clear sky. While adjusting the telescope’s position, Fossey noticed a star overlaid on the galaxy which he did not recognise from previous observations.

They inspected online archive images of the galaxy, and it became apparent that there was indeed a new starlike object in M82. With clouds closing in, they switched to taking a rapid series of 1- and 2-minute exposures through different colour filters to check that the object persisted, and to be able to measure its brightness and colour.

The original press release, and a BBC story repeating it, claimed that this is the nearest supernova since Supernova 1987A in the Large Magellanic Cloud. In fact, SN 1993J in M81 was at essentially the same distance within the uncertainties, and two subsequent supernovae, SN 2004am and SN 2008iz (an obscured radio supernova), occurred within M82 itself.

However, this is said to be the nearest Type Ia supernova since 1972. That's the kind so valuable for measuring the size and expansion rate of the universe. Despite the dimming and reddening, astronomers hope that SN 2014J will provide new details about exactly what happens in these "standard-candle" explosions.

Update: Supernova in Another Messier Galaxy

Don't get your hopes up, but another supernova, SN 2014L, has appeared in M99 in Coma Berenices high in the late-night sky. It was only magnitude 15.7 as of January 28.4 UT, way too faint for most amateur scopes, but it was only about magnitude 17.2 when discovered on January 26th. More information and images.

It was still being reported at the same magnitude 15.7 as of January 29.4 UT.

M99 is a spiral galaxy about 50 million light-years away in the Virgo Cluster, four times as far as M82. It has hosted three previous known supernovae (1967H, 1972Q, and 1986I) and the odd lesser outburst PTF 10fqs.

Posted by Alan MacRobert, January 31, 2014
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First comments (from 20)

Backyard astronomy

Posted by Anthony Barreiro January 22, 2014 At 11:08 AM PST
This is very exciting news, thanks. I'm glad I happened to check the S&T website today. Tonight, Wednesday January 22, was already going to be interesting, with Algol at minimum brightness at 2220 PST, Europa and Europa's shadow transiting Jupiter from 2018 to 2352 PST, and Jupiter's great red spot at the central meridian at 2232 PST. We're having a drought here in California, so the weather has been remarkably good for skywatching. I'll add M82's supernova to my list for tonight. By the way, Sky and Telescope used to send out occasional email alerts for special events like supernovae. Do you still do this? Do I need to sign up again?

on-line video of M82 SN

Posted by Ron January 22, 2014 At 11:25 AM PST
Check out this video on youtube. they have the SN live and even talk about (lack of) them in M82 and don't recognize a new star is right there on the image!

Nearest Supernova?

Posted by Jon Hanford January 23, 2014 At 06:18 AM PST
Not only was SN1993J in M81 at about the same distance, two supernovae have appeared in M82 since 1987, SN2004am and SN2008iz(a radio supernova). SN2004am, a Type II-P SN, appeared very close to the position of the current SN: Additional info on these two supernovae in M82 can be found here:

a special supernova

Posted by Paul Vondra January 23, 2014 At 09:23 PM PST
My 86-year-old mother passed away this afternoon, peacefully, at home, after suffering a second stroke on Monday. She never regained consciousness. Unscientific though it is, I will always think of this as her Special Guidelight as she sets sail across that Vast and Unknown Sea. I live in Pittsburgh where it has been cloudy and bitterly cold since I first heard of the supernova yesterday but I intend to set up my scope the first clear chance i get regardless of the temp. to see it. The only other supernova I've ever seen was the one in M101 a year or two back and I'm hoping this one may get a little brighter.

a special supernova

Posted by Bruce Mayfield January 24, 2014 At 05:15 AM PST
Paul, sorry to read of your loss. I lost my mother a few years back. While we know scientifically that astronomical and human events are unrelated, seeing something special at a time of great loss can bring comfort, so I hope you are able to personally observe SN2014J, and may your heart be warmed when you do. But science alone doesn’t offer much hope though. Reflecting on these verses were some of the many that brought me hope and comfort when my mother passed; Job 14:14,15 and Acts 24:15.

Max Mag of M82 SN

Posted by Tom Hoffelder January 24, 2014 At 02:50 PM PST
Happy to see the "very tentative" prediction of mag 10.1 as the maximum. I have seen other sources saying as bright as 8. They must be ignoring the reddening caused by dust.

M82 supernova

Posted by John Mahlberg January 24, 2014 At 06:55 PM PST
I could just barely glimpse the super nova tonight through a 90 MM scope in central Colorado.

M82 Supernova

Posted by mrvair January 25, 2014 At 09:38 AM PST
Events like this supernova remind me of Psalms 19:1.

M82 Supernova

Posted by Bruce January 25, 2014 At 04:15 PM PST
That's one of my favorite verses too Mrvair. I hope to see this, but only have 10x50 binoculars. In a fairly dark sky, what appartent magnatude would this SN have to reach to be detectable?

M82 Supernova in Binoculars

Posted by Hal Lane January 25, 2014 At 07:48 PM PST
Bruce, This PDF: "Limiting Magnitude in Binoculars" answers your question: "what appartent magnatude would this SN have to reach to be detectable [in 10x50 binos]?" -- but you'll have to do a bit of reading to find it... Note that the author of the paper used a tripod and averted vision (looking very slightly away from the object being looked for) for their tests... In the PDF the 3rd page has a list of useful abbreviations used in the paper. Please post whether you were able to see 2014J or not, and the circumstances (sky darkness, etc.) of your attempt! - Hal Lane

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Good Clear Skies
Colin James Watling
Various Voluntary work-Litter Picking for Parish Council (Daytime) and also a friend of Kessingland Beach (Watchman)
Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)

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