astronomy

TX Piscium

TX Piscium 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 TX Piscium rather than just read about it. In short: TX Piscium (19 Piscium) is a variable red giant star in the constellation Pisces. It is amongst the reddest naked eye stars, with a significant reddish hue when seen in binoculars.

Key takeaways

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

Reference excerpt

TX Piscium (19 Piscium) is a variable red giant star in the constellation Pisces. It is amongst the reddest naked eye stars, with a significant reddish hue when seen in binoculars. It is approximately 800 light years from Earth. It is close to—and sometimes considered part of—the asterism on the western end of the constellation called the circlet of Pisces.

Spectrum TX Piscium is a very red star, 2.6 magnitudes fainter at blue wavelengths than in the middle of the visual range, and another 3.3 magnitudes fainter in the ultraviolet. It has been given a spectral class C7,2, indicating a relatively cool carbon star with only modest C2 band strength. It has alternately been classified as C-N5 C24, suggesting a warmer star with stronger C2 bands. Spectral features have been observed to vary.

Variability

The apparent magnitude of TX Piscium varies between +4.9 and +5.5 and it is classified as a slow irregular variable. Photometry has shown some periodicity in the brightness of 224 days, and some spectral variation over 450 days, suggesting the star is not entirely irregular. The star apparently lies on the period-luminosity relation corresponding to fundamental mode pulsations, unusual for a low-amplitude semi-regular or irregular variable which usually pulsate in an overtone. The angular diameter has been measured at around 10 mas, although this varies depending on the observed wavelength and the atmosphere appears to be highly asymmetric. There may be one or more "blobs" of ejected material near the star. Some observations show the angular diameter to change in synchrony with the visual brightness.

Properties TX Piscium is a thermally-pulsing asymptotic giant branch (TP-AGB) red giant star, which means that it is alternately fusing helium in a shell around its core and fusing hydrogen in a shell closer to its surface. Stars on the TP-AGB are generally unstable, with high mass loss and pulsations. The periodic flashes of the helium shell in a red giant star are known as thermal pulses and cause the hydrogen shell to be extinguished. This creates strong convection and the third dredge-up (TDU) which brings helium fusion products such as carbon to the surface. After several TDUs, the abundance of carbon in the atmosphere begins to exceed that of oxygen and then the star is known as a carbon star. In TX Piscium, the carbon/oxygen ratio is calculated to be 1.03, which is at the low end of the scale of carbon stars. It is thought to be a relatively new carbon-rich red giant star. TX Piscium has a mass of approximately 2 M☉. Modelling of its observed properties suggest a mass between 1 and 2 M☉, while evolutionary models suggest a mass between 2 and 3 M☉. In particular, stars with a mass below 2 M☉ are not expected to become carbon stars. The temperature of TX Piscium is thought to vary between 3,080 K at minimum visual brightness and 3,170 K at visual maximum. Similarly, its luminosity varies between 7,019 and 7,876 L☉. Many of its physical properties are uncertain due to uncertainty in its distance. The Hipparcos parallax corresponds to a distance of 275 parsecs, but other estimates give distances as high as 315 parsecs. These properties imply a radius of 295 R☉; if TX Piscium took the place of the Sun, it would extend beyond the orbit of the Earth, but not reach Mars.

References

Illustrations

Worked examples

Example 1 — a first encounter with TX Piscium

Start with the simplest possible case. Write down what TX Piscium 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 TX Piscium 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 TX Piscium 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 TX Piscium

In research: TX Piscium 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 TX Piscium 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: TX Piscium is common in secondary-school and first-year university syllabi. It links to neighbouring topics Asymptotic-giant-branch stars, Bright Star Catalogue objects, Carbon stars, so understanding it makes those chapters shorter.
In everyday life: Look for TX Piscium 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 TX Piscium in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TX Piscium 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 TX Piscium out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TX Piscium in simple terms?

TX Piscium (19 Piscium) is a variable red giant star in the constellation Pisces. It is amongst the reddest naked eye stars, with a significant reddish hue when seen in binoculars.

Why does TX Piscium 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 TX Piscium?

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 TX Piscium.