T Pyx on April 15, 2011

T Pyxidis in outburst on April 15th. North is up. See before-and-after animation.

Ernesto Guido and Giovanni Sostero

The recurrent nova T Pyxidis, which had its last outburst in December 1966 and has been very overdue for its next, finally began a new flareup on April 14th. By the next day it had brightened to about magnitude 8.4. In 1966–67 it reached 6.5 within about a month, and now it has done so again.

Here's a blink animation showing before and after, courtesy Ernesto Guido and Giovanni Sostero in Italy. South is up.

The star is in the dim constellation Pyxis east of Puppis and Canis Major, sinling out of sight for northern observers in May. (Here are finder and comparison-star charts from Sky & Telescope. For larger-scale comparison-star charts, you can use the chart-making site of the American Association of Variable Star Observers).

More information on T Pyx. Old but good AAVSO article. Current AAVSO observing campaign page.

As a white dwarf accreting mass from a binary partner, T Pyx is a prime candidate to explode completely as a Type Ia supernova within the next 10 million years. Last year, careless reporting led to a flurry of media buzz that if it blows up soon it could endanger Earth. Not so. At its distance of about 3,000 light-years, T Pyx would shine as brightly as magnitude –9 if it went Type Ia (as bright as a thick crescent Moon), but its radiation wouldn't harm us. The current Wikipedia article on T Pyx explains this story well.

In its past known outbursts (1890, 1902, 1920, 1944, and 1966), T Pyx took about 20 days to reach 7th magnitude or so and remained 8th mag or brighter for about two months.

Elaborating on this, Bradley Schaefer writes: "Judging from the 1967 eruption light curve, the current eruption light curve will... slowly rise to a peak near V=6.4 around 20 May, slowly fade to V=10 by middle August, then have a sudden drop by two magnitudes over the next 20 days (with drop being invisible due to the Sun). The 1967 eruption did show fast intra-night variations, but the old data does not have the time resolution to tell what is going on."

UPDATE May 13: As T Pyx disappears to the twilight horizon for Northern Hemisphere observers, it has brightened to magnitude 6.5 as of last night according to various observers reporting to the AAVSO. Here are recent observations and a light curve for the most recent 50 days.


Image of David Watts

David Watts

May 6, 2011 at 3:42 pm

Why do you people not first check what you write in your e-mail columns?

When you click on the AAVSO star maps of T Pyx that you cite in your story, they are not available.

Either this is poor editing or no editing. Either way your readers lose.

Thanks for listening.

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Image of Alan MacRobert

Alan MacRobert

May 6, 2011 at 7:50 pm

Sorry about the charts; they've vanished from the AAVSO site. Instead, you can make charts at the AAVSO's chartins site here:


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Image of lightningsgirl15@aol.com

[email protected]

May 7, 2011 at 9:54 am

Of course that "recent" flare up happened a good chunk of time ago! Looking forward into space is looking backward into time..the late great Carl Sagan pointed that out quite frequently!

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