New Supernova In Virgo Bright Enough For Modest Telescopes

Dragon berthed to the Harmony node of the International Space Station. Credit: NASA TV

The hatch between the newly-arrived SpaceX Dragon capsule and the space station was opened early this morning as the crew began today to unload food, clothes and batteries.

Astronaut Don Pettit commented on the “new car smell” and well-designed layout of the ship. They’ll reload the capsule with science equipment and send it back on its way to Earth soon. The commercial craft was designed to be re-useable;  routine flights to the space station are scheduled to begin in August.

Supernova 2012 cg is in the "V" of Virgo west of Epsilon Virginis and not far from Rho and 20 Virginis. Created with Stellarium

On May 17 the automated Lick Supernova Supernova Search (LOSS)  discovered a new supernova in the galaxy NGC 4424 in the constellation Virgo not far from the planet Saturn. Only 18th magnitude at the time of discovery and impossibly faint to see, the star has since skyrocketed to around 12.7, making it a worthy target for amateur telescopes 6 inches and larger.

Last night it outshone the galaxy’s own nucleus, which is comprised of at least several billion stars. That gives you an idea of how brilliant this exploding star truly is. The supernova is embedded within the galaxy’s hazy disk some 17 arc seconds east of center.

Supernova 2012 cg is 17" east and 1.5" north of NGC 4424's nucleus. The picture was taken by amateur astronomer William Wiethoff of Port Wing, Wis. on May 21. The numbers next to the stars below the galaxy are magnitudes. The higher the number, the fainter star. View is shown through a typical telescope with south up and east to the right.

Using a spectrograph, a device that breaks up a star’s light into a rainbow fingerprint of colors, astronomers have determined that 2012 cg is a Type Ia supernova. Before the explosion, the star was a white dwarf, a superdense, planet-sized object with the mass of the sun. Tiny but mighty, the white dwarf’s powerful gravity pulled material from a nearby companion star down to its surface.

In a Type Ia supernova, a white dwarf (left) draws matter from a companion star until its mass hits a limit which leads to collapse and then explosion.

When a dwarf puts on enough pounds to exceed 1.4 times the sun’s mass, it can longer support itself and collapses and self-detonates in an explosion that blasts it to bits. Lucky earthlings can witness the incredible event from the comfort of their patios.

NGC 4424 is one of many galaxies in Virgo, so take your time using the map to arrive at the right one.

Star-hop from Epsilon to Rho to 20 and over to a trio of galaxies including NGC 4424. It shines 11th magnitude, and looks like a fuzzy patch. The supernova is the little star blazing inside it. Stars shown to mag. 9.5. Created with Chris Marriott's SkyMap software

Since 2012 cg was discovered early in the explosive phase, it brightened quickly and is still climbing. You can watch it change in the coming days and weeks by using the star magnitudes – direct from the American Association of Variable Star Observers (AAVSO) – shown in the photo above. That’s how I estimated the supernova’s magnitude at 12.7 last night May 25. For more information and photos, please stop by David Bishop’s Latest Supernovae site, the one-stop shop place for what’s shakin’ in the world of exploding stars.

11 Responses

  1. radley

    In 2008 October in the daytime ! I saw a white flash of light in Virgo! right where this is at ! it looked like a star ! didn’t know it was a star exploding ! kool

    1. astrobob

      Hi Radley,
      I wish it were true. You saw something interesting that’s for sure but not the supernova in Virgo. For that you would have needed a telescope and dark sky. While supernovas are incredibly brilliant, when they happen in a galaxy 40 million light years away, they appear like faint stars (at night only).

  2. radley

    astro Bob I was out today 2013 October 25th Friday 2:57pm Central saw that flash of light again I think its possible a star and I can point to exactly where I saw it on a chart that I have already marked will try tomorrow to go out at same time with a camera it was on the right side of the sun I guess now I could use a telescope at night on that spot and see if somethings there same flash I saw in 2008 October

    1. astrobob

      2:57 p.m. – given the time, could it have been a glint or flash from a passing plane? The other possibility is a very bright reflective flare from an Iridium satellite. If you give me your location I check on possible satellite flares.

      1. Radley

        Talladega Alabama Usa I guess It could have been a plane or satlight really don’t know for sure what it was. next day it was cloudy haven’t seen it again no picture

        1. Radley

          2008 when I saw the white light flash looking like a star it was brighter than what I saw this year but both in about same part the sky in daytime around the same time

  3. Radley

    you can see supernova in the daytime ! I have read about if Betelgeuse exploded you could see that in the day ! and other supernova seen in daytime and gamma ray bursts could be seen in the daytime in 2008 with the naked eye ! Kepler’s Supernova 1604 Star was brighter at its peak than any other star in the night sky,, with an apparent magnitude of −2.5. It was visible during the day for over three weeks.

    1. astrobob

      Hi Radley,
      Yes, you can see a supernova in the daytime – sorry, I should have qualified my reply. However they have been no supernovas visible in the daytime since 1572 (Kepler’s 1604 star might have been seen in the daytime shortly after sunrise or before sunset by a dedicated observer). When I replied to your question I was referring to the present time. The 2008 supernova was bright in gamma rays but had anyone seen it, it would have been a faint 6th magnitude and visible only from a dark sky.

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