T Pyxidis
Encyclopedia
T Pyxidis is a binary star
system in the constellation
Pyxis
estimated at about 1000 pc from Earth
. It contains a sun-like star and a white dwarf
. Because of their close proximity and the larger mass of the white dwarf, it draws matter from the larger, less massive star which causes periodic thermonuclear explosions to occur. T Pyx is a recurrent nova
and nova remnant
in the constellation
Pyxis
.
The usual apparent magnitude
of this star system is 15.5, but there occurred eruptions with maximal apparent magnitude of about 7.0 in the years 1890, 1902, 1920, 1944, 1966 and 2011. Evidence seems to indicate that T Pyxidis may have increased in mass despite the nova eruptions, and is now close to the Chandrasekhar limit
when it might explode as a Supernova. When a white dwarf reaches this limit it will collapse under its own weight and cause a Type 1a supernova.
. The X-radiation
that reaches Earth, however, would be less than the X-radiation of a single average solar flare. However, Dr. Sion's calculations were challenged by professor Alex Filippenko who said that Sion had possibly miscalculated the damage that could be caused by a T Pyxidis supernova. He had used data for a far more deadly gamma-ray burst (GRB) exploding 1 kiloparsec
from Earth, not a supernova, and T Pyxidis certainly is not expected to produce a GRB. According to another expert, "A supernova would have to be 10 times closer [to Earth] to do the damage described." Mankind
survived when the Crab Nebula
supernova went off at a distance of about 6500 light-years in the year 1054. If this star were to explode as a type Ia supernova at its estimated distance of 3300 light-years, it would have an apparent magnitude of around -9.3, about as bright as the brightest Iridium (satellite) flares.
It has been reported that T. Pyx would "soon" become a supernova, .
However, when contacted by Scientific American, Dr Sion said that the term "soon" in the press announcement meant that "At the accretion rate we derived, the white dwarf in T Pyxidis will reach the Chandrasekhar Limit in ten million years."
By that time it will have moved far enough away from the solar system to have little effect.
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
system in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Pyxis
Pyxis
Pyxis is a small and faint constellation in the southern sky. Its name is Latin for a mariner's compass...
estimated at about 1000 pc from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. It contains a sun-like star and a white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
. Because of their close proximity and the larger mass of the white dwarf, it draws matter from the larger, less massive star which causes periodic thermonuclear explosions to occur. T Pyx is a recurrent nova
and nova remnant
Nova remnant
A nova remnant is made up of the material either left behind by the gigantic explosion of a star in a nova, or from the bubbles of gas blasted away in a recurrent nova. It has an expansion velocity of around 1000 km/s, and has a lifetime of a few centuries. Considering their short lifetimes, nova...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Pyxis
Pyxis
Pyxis is a small and faint constellation in the southern sky. Its name is Latin for a mariner's compass...
.
The usual apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of this star system is 15.5, but there occurred eruptions with maximal apparent magnitude of about 7.0 in the years 1890, 1902, 1920, 1944, 1966 and 2011. Evidence seems to indicate that T Pyxidis may have increased in mass despite the nova eruptions, and is now close to the Chandrasekhar limit
Chandrasekhar limit
When a star starts running out of fuel, it usually cools off and collapses into one of three compact forms, depending on its total mass:* a White Dwarf, a big lump of Carbon and Oxygen atoms, almost like one huge molecule...
when it might explode as a Supernova. When a white dwarf reaches this limit it will collapse under its own weight and cause a Type 1a supernova.
Effect on Earth
Because of its relative proximity, some contend that a T Pyxidis supernova could have a significant impact on Earth. The received gamma radiation would equal the total (all spectra) radiation of approximately 1000 solar flares, but a type Ia supernova would have to be closer than 1000 pc to cause significant damage to the ozone layerOzone layer
The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone . This layer absorbs 97–99% of the Sun's high frequency ultraviolet light, which is potentially damaging to the life forms on Earth...
. The X-radiation
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
that reaches Earth, however, would be less than the X-radiation of a single average solar flare. However, Dr. Sion's calculations were challenged by professor Alex Filippenko who said that Sion had possibly miscalculated the damage that could be caused by a T Pyxidis supernova. He had used data for a far more deadly gamma-ray burst (GRB) exploding 1 kiloparsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
from Earth, not a supernova, and T Pyxidis certainly is not expected to produce a GRB. According to another expert, "A supernova would have to be 10 times closer [to Earth] to do the damage described." Mankind
Human
Humans are the only living species in the Homo genus...
survived when the Crab Nebula
Crab Nebula
The Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus...
supernova went off at a distance of about 6500 light-years in the year 1054. If this star were to explode as a type Ia supernova at its estimated distance of 3300 light-years, it would have an apparent magnitude of around -9.3, about as bright as the brightest Iridium (satellite) flares.
It has been reported that T. Pyx would "soon" become a supernova, .
However, when contacted by Scientific American, Dr Sion said that the term "soon" in the press announcement meant that "At the accretion rate we derived, the white dwarf in T Pyxidis will reach the Chandrasekhar Limit in ten million years."
By that time it will have moved far enough away from the solar system to have little effect.
2011 Outburst
Mike Linnolt has detected T Pyx first outburst in nearly 45 years. He detected it on April 14 2011 at magnitude 13. According to AAVSO observers, it had since reached magnitude 7.5 in visual and V bands by April 27 and magnitude 6.8 by May 3.External links
- AAVSO Variable Star Of The Month April, 2002: T Pyxidis PDF / HTML (17 July 2010)
- AAVSO: Quick Look View of AAVSO Observations (get recent magnitude estimates for T Pyx)
- Interview with Brad Schaefer about recurrent novae, and T Pyx (@19:40 into recording : 30 March 2009)
- Variable star T PYXIDIS
- Astronomers await a nova (Space.com 22 December 2006)
- Sion, Edward. A Supernova Could Nuke Us. Big Think.
- Astronomy Picture of the Day
- Explosive Nearby Star Could Threaten Earth