astronomy

T Pyxidis

T Pyxidis is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand T Pyxidis rather than just read about it. In short: T Pyxidis (T Pyx) is a recurrent nova and nova remnant in the constellation Pyxis. It is a binary star system and its distance is estimated at 4,783 parsecs (15,600 light-years) from Earth.

Key takeaways

T Pyxidis belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect T Pyxidis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of T Pyxidis from memory before moving on to harder problems.

Reference excerpt

T Pyxidis (T Pyx) is a recurrent nova and nova remnant in the constellation Pyxis. It is a binary star system and its distance is estimated at 4,783 parsecs (15,600 light-years) 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, the latter draws matter from the larger, less massive star. The influx of matter on the white dwarf's surface causes periodic thermonuclear explosions to occur. The usual apparent magnitude of this star system is 15.5, but there have been observed 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 Ia supernova.

Effect on Earth

Because of its relative proximity, some—in particular, Edward Sion, astronomer & astrophysicist at Villanova University, and his team therefrom—contend that a Type Ia supernova could have a significant impact on Earth. The received gamma radiation would equal the total (all spectra) radiation of approximately 1,000 solar flares, but the Type Ia supernova would have to be closer than 1,000 parsecs (3,300 light-years) to cause significant damage to the ozone layer, and perhaps closer than 500 parsecs. The X-radiation that reaches Earth in such an event, however, would be less than the X-radiation of a single average solar flare. However, Sion's calculations were challenged by Alex Filippenko of the University of California at Berkeley 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) occurring 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 radiation from the Crab Nebula supernova, at a distance of about 6,500 light-years, reached Earth in the year 1054. A Type Ia supernova at a distance of 3,300 light-years would have an apparent magnitude of around -9.3, about as bright as the brightest Iridium (satellite) flares. Recent data indicates his distance estimate is five times too close. Astronomers used NASA's Hubble Space Telescope to observe the light emitted during its latest outburst in April 2011. The team also used the light echo to refine estimates of the nova's distance from Earth. The new distance is 15,600 light-years (4780 pc) from Earth. Previous estimates were between 6,500 and 16,000 light-years (2000 and 4900 pc). It has been reported that T Pyx would "soon" become a supernova. However, when Scientific American contacted Sion, it became apparent that "soon" was meant in astronomical terms: Sion said that "soon" in the press announcement meant "[a]t 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 detected T Pyx's first outburst in nearly 45 years on April 14, 2011, at magnitude 13. According to AAVSO observers, it reached magnitude 7.5 in the visual and V bands by April 27, and reached magnitude 6.8 by May 3.

X-ray source T Pyxidis is a super soft X-ray source.

References

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. NASA Astronomy Picture of the Day: T Pyxidis: Recurrent Nova (25 September 1997) Explosive Nearby Star Could Threaten Earth

Illustrations

Worked examples

Example 1 — a first encounter with T Pyxidis

Start with the simplest possible case. Write down what T Pyxidis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to T Pyxidis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about T Pyxidis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of T Pyxidis

In research: T Pyxidis appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses T Pyxidis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: T Pyxidis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Binary stars, Nova remnants, Objects with variable star designations, so understanding it makes those chapters shorter.
In everyday life: Look for T Pyxidis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study T Pyxidis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what T Pyxidis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain T Pyxidis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is T Pyxidis in simple terms?

T Pyxidis (T Pyx) is a recurrent nova and nova remnant in the constellation Pyxis. It is a binary star system and its distance is estimated at 4,783 parsecs (15,600 light-years) from Earth.

Why does T Pyxidis matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study T Pyxidis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on T Pyxidis.