T Pyxidis

Lore & Background

T Pyxidis has experienced observed eruptions in 1890, 1902, 1920, 1944, 1966, and 2011. Its usual apparent magnitude is 15.5, but during eruptions it has reached about 7.0.

The 2011 outburst was first detected on April 14 at magnitude 13, and by May 3 it had reached magnitude 6.8. Evidence suggests that T Pyxidis may have increased in mass despite the nova eruptions and is now close to the Chandrasekhar limit, at which point the white dwarf would collapse and cause a Type Ia supernova. The system is also a super soft X-ray source.

Reader's Guide

T Pyxidis has drawn attention because of its potential to become a Type Ia supernova and the possible effects on Earth. Some astronomers, including Edward Sion and his team, have contended that a Type Ia supernova at T Pyxidis's distance could have a significant impact on Earth, with gamma radiation equal to about 1,000 solar flares. However, these calculations were challenged by Alex Filippenko, who noted that Sion had used data for a gamma-ray burst rather than a supernova. Another expert stated that a supernova would need to be ten times closer to cause the described damage.

The Crab Nebula supernova at about 6,500 light-years had no catastrophic effect on Earth. Furthermore, Sion later clarified that 'soon' meant in astronomical terms—the white dwarf would reach the Chandrasekhar limit in ten million years, by which time the system will have moved far enough away to have little effect. The distance estimate was refined using Hubble Space Telescope observations of the 2011 outburst's light echo, yielding 15,600 light-years (4780 pc), which is five times farther than some earlier estimates.

Did You Know?

• Its 2011 outburst was the first in nearly 45 years.