astronomy

RZ Piscium

RZ 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 RZ Piscium rather than just read about it. In short: RZ Piscium (or RZ Psc) is a UX Orionis type variable star 608 light-years (186 pc) away, in the constellation Pisces. Over the years, the star has been found to brighten and dim erratically, dimming by as much as a tenth of its usual luminosity.

Key takeaways

RZ 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 RZ Piscium to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of RZ Piscium from memory before moving on to harder problems.

Reference excerpt

RZ Piscium (or RZ Psc) is a UX Orionis type variable star 608 light-years (186 pc) away, in the constellation Pisces. Over the years, the star has been found to brighten and dim erratically, dimming by as much as a tenth of its usual luminosity. RZ Piscium has been found to emit large amounts of infrared radiation, suggesting the presence of a substantial mass of gas and dust orbiting the star, possibly from a "disrupted planet".

Disrupted planet Because of the infrared excess and rapid light variations, astronomers conclude that:

destruction of one or more massive orbiting bodies has recently occurred within 1 au of the star, and we are viewing the aftermath of such an event along the plane of the orbiting debris. According to astronomer Ben Zuckerman:

Most sun-like stars have lost their planet-forming disks within a few million years of their birth. The fact that RZ Piscium hosts so much gas and dust after tens of millions of years means it is probably destroying, rather than building, planets.

Observations

In 2017, RZ Piscium was studied using the XMM-Newton satellite, the Shane 3-meter telescope at Lick Observatory in California and the 10-meter Keck I telescope at W. M. Keck Observatory in Hawaii. The temperature of the star was found to be about the same as the Sun (5,600 K (5,330 °C)). Further, the star was found to produce about a thousand times more x-rays than the Sun, suggesting that the star is relatively young. On the other hand, RZ Piscium was found to contain a relatively small amount of surface lithium, which suggests the star is between 30 − 50 million years old; this is somewhat "old" for a star with so much circumstellar dust. Most young stars that are as dusty as RZ Piscium may be producing planets, but given its relatively advanced age, RZ Piscium may be destroying and consuming its planets instead. In 2020, a red dwarf companion with the mass of 0.12 Solar mass was detected with a projected separation of 23 AU from the primary star. The incandescence of the companion star thus make up about one third of excess infrared emission previously attributed to the dust. Observations with TESS did result in the detection of 24 transits by exocomets. The transits have absorption depths between 1-20%. This is the second system, after Beta Pictoris that shows a large population of comets. The transit rate is about double compared to Beta Pictoris, with 0.40 exocomets per day for RZ Piscium. The exocomets have a size of 1-7 km.

See also List of stars that have unusual dimming periods

References

External links Video (01:00) − RZ Piscium on YouTube, star with unusual light fluctuations (21 December 2017). Video (13:46) − "Tabby's Star" on YouTube, a presentation by Tabetha S. Boyajian Video (31:00) − "Tabby's Star" on YouTube, a presentation by Issac Arthur

Illustrations

Worked examples

Example 1 — a first encounter with RZ Piscium

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

In research: RZ 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 RZ 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: RZ Piscium is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2017 in outer space, 2017 in science, Extrasolar planetary collisions, so understanding it makes those chapters shorter.
In everyday life: Look for RZ 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 RZ Piscium in 20 minutes

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

Frequently asked questions

What is RZ Piscium in simple terms?

Why does RZ 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 RZ 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 RZ Piscium.