astronomy

HD 85951

HD 85951 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 HD 85951 rather than just read about it. In short: HD 85951 (HR 3923), formally named Felis , is a solitary orange-hued star in the constellation Hydra. It has an apparent magnitude of 4.94, making it faintly visible to the naked eye under ideal conditions.

Key takeaways

HD 85951 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HD 85951 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 85951 from memory before moving on to harder problems.

Reference excerpt

HD 85951 (HR 3923), formally named Felis , is a solitary orange-hued star in the constellation Hydra. It has an apparent magnitude of 4.94, making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements, the object is about 570 light-years away from the Sun and is receding with a heliocentric radial velocity of 50 km/s.

Nomenclature HD 85951 was the brightest star in the now-obsolete constellation of Felis, and was designated c Felis in Bode's star chart. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Felis for this star on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.

Properties HD 85951 is an evolved red giant with a stellar classification of K5 III. It is currently on the asymptotic giant branch, generating energy via fusion of hydrogen and helium shells around an inert carbon core. At present, Felis has 6.4 times the mass of the Sun and, due to its evolved status, has an enlarged radius of 56.7 R☉. It radiates at a bolometric luminosity 721 times that of the Sun from its photosphere at an effective temperature of 3,875 K. Felis has an iron abundance 66% that of the Sun, making it metal deficient.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 85951

Start with the simplest possible case. Write down what HD 85951 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 HD 85951 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 HD 85951 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 HD 85951

In research: HD 85951 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 HD 85951 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: HD 85951 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bright Star Catalogue objects, Durchmusterung objects, Henry Draper Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 85951 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 HD 85951 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 85951 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 HD 85951 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 85951 in simple terms?

Why does HD 85951 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 HD 85951?

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 HD 85951.