astronomy

HV 11423

HV 11423 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 HV 11423 rather than just read about it. In short: HV 11423 (PMMR 114 or 140 LI-SMC) is a red supergiant star in the Small Magellanic Cloud. It is about 200,000 light-years away towards the constellation of Tucana.

Key takeaways

HV 11423 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HV 11423 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HV 11423 from memory before moving on to harder problems.

Reference excerpt

HV 11423 (PMMR 114 or 140 LI-SMC) is a red supergiant star in the Small Magellanic Cloud. It is about 200,000 light-years away towards the constellation of Tucana.

Visibility The spectral type of HV 11423 is variable, from K0-1I in December 2004, to M4I in December 2005, and back to K0-1I by September 2006. Very Large Telescope file spectra show that in December 2001 the star was even cooler (M4-5I). By contrast, in October 1978 and a year later, it appeared as a star of class M0I. The spectral type M4-5 is the latest observed in a supergiant of the Small Magellanic Cloud.

Characteristics

HV 11423 is one of the largest known stars with an estimated radius over 1,000 times larger than the sun. It is also a variable star with a variation of up 2 magnitudes at visual wavelengths but essentially constant in the infrared. It is listed in the General Catalogue of Variable Stars as a slow irregular variable, but a period of 720 days has been calculated, as well as a long secondary period of 1,817 days. The bolometric luminosity is about 200,000 times more than Sun, making it one of the most luminous cool supergiants, and appears to have remained unchanged during the brightness and spectral variations. It is thought that the star is currently undergoing a period of intense instability, in which its effective temperature changes from 4,300 to 3,300 K in a time scale of months; V-band variability may be due primarily to variations in temperature as well as changes in the local extinction due to the creation and dissipation of circumstellar dust. It is speculated that the star may be nearing the end of its life, although the mass loss rate is still moderate at 0.0906 M☉ per million years.

See also Similar red supergiants or hypergiants with strong spectral variability

BC Cygni KW Sagittarii S Persei VX Sagittarii Westerlund 1 W26

References

Illustrations

Worked examples

Example 1 — a first encounter with HV 11423

Start with the simplest possible case. Write down what HV 11423 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 HV 11423 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 HV 11423 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 HV 11423

In research: HV 11423 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 HV 11423 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: HV 11423 is common in secondary-school and first-year university syllabi. It links to neighbouring topics K-type supergiants, M-type supergiants, PMMR objects, so understanding it makes those chapters shorter.
In everyday life: Look for HV 11423 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 HV 11423 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HV 11423 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 HV 11423 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HV 11423 in simple terms?

HV 11423 (PMMR 114 or 140 LI-SMC) is a red supergiant star in the Small Magellanic Cloud. It is about 200,000 light-years away towards the constellation of Tucana.

Why does HV 11423 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 HV 11423?

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 HV 11423.