T Pyx 2011 outburst

The 2011 eruption of T Pyx.

T Pyx lies 6,000 light years away in the dim southern constellation Pyxis, the Mariner’s Compass. T Pyx is easily observable from the Southern Hemisphere. T Pyxidis belongs to a small and seemingly “exclusive” group of cataclysmic variable stars called recurrent novae (NR). There have been five previous eruptions  of  T pyx with the first discovered in 1890, then 1902, 1920, 1944 and 1966.

Images from ground-based telescopes have shown a smooth shell of gas surrounding T Pyxidis. But closer inspection by the Hubble Space telescope reveals that the shell is not smooth at all, but a collection of more than 2,000 gaseous blobs packed into an area that is one light-year across.

The 2011 Outburst of T Pyx was first noticed by Michael Linnolt of Hawaii on April 14 at visual magnitude 13.0, nearly 45 years since the last outburst in 1966.

Pre-outburst activity of T Pyx.

T Pyx has been on my observing program for many years in which I have been able to observe the star at minimum around magnitude 15.4. On April 5, 2011 the first thing that surprised me was that T Pyx was brighter than normal at magnitude 14.5. This was unusual.  I made frequent observations and it rose to magnitude 14.4. T pyx was rising and I started to get excited……could this be the awaited outburst? I stayed with it for hours in which it remained around 14.5 and by nights end it slightly faded to magnitude 14.7. The following night on April 6 T Pyx was still above normal brightness at 14.7, April 7, 14.8 and April 10, at magnitude 15.0, still slightly above it’s minimum brightness.

After years of keeping a close eye on T Pyx I have no doubt that there was some pre-outburst activity going on around April 5, and onwards prior to the eruption on April 14. You will also notice that some activity occurred about 100 days earlier between magnitude 15.0 and 15.4.

My visual observations on T Pyx showing the pre-outburst activity and ongoing outburst. This outburst will last for months so further updates of the light curve will be added.

Current light curve is up to January 14, 2013 with T Pyx currently at magnitude 15.0. T Pyx is pretty well back to quiescence level with the light curve starting to flattening out at magnitude 15.0.

T Pyx

Light curve showing the pre-eruption about 18 days before the main event. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB)
anticipatory rise closely spaced before a nova eruption.

T Pyx2

C0-authored paper on the T Pyx eruption

The 2011 Eruption of the Recurrent Nova T Pyxidis; the Discovery, the Pre-eruption Rise, the Pre-eruption Orbital Period, and the Reason for the Long Delay arXiv:1109.0065v1


“We report the discovery by M. Linnolt on JD 2455665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova) with fine time resolution and in three filters. The speed of the rise peaked at 9 mag/day, while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report the discovery by R. Stubbings of a pre-eruption rise starting 11 days before the eruption, peaking 1.1 mag brighter than its long-time average, and then fading back towards quiescence five days before the eruption. This unique and mysterious behavior is only the fourth known anticipatory rise/dip closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to February 2011, where the orbital period is fast increasing with P/Pdot=+313,000 years. From 2008-2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622916+-0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of 10^{-6.0+-0.5} Msun/yr for mass leaving the companion star. We report 6114 magnitudes between 1890 and 2011, for an average B=15.59+-0.01 from 1967-2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. We present a model for the infrared-to-X-ray emission during quiescence as being from a 34,000 K blackbody nearly filling the Roche lobe (caused by the very high accretion rate creating an extended envelope around the accretion column) plus a nu^0.9 non-thermal component (from the optically-thin outer and circumbinary regions). “

2 Responses to T Pyx 2011 outburst

  1. Great work Rod, I am proud to be part of the Paper as well,

    Cheers, Rolf


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