astronomy

HD 111395

HD 111395 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 111395 rather than just read about it. In short: HD 111395 is a single, variable star in the northern constellation of Coma Berenices. It has the variable star designation LW Comae Berenices; HD 111395 is the Henry Draper Catalogue designation.

Key takeaways

HD 111395 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 111395 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 111395 from memory before moving on to harder problems.

Reference excerpt

HD 111395 is a single, variable star in the northern constellation of Coma Berenices. It has the variable star designation LW Comae Berenices; HD 111395 is the Henry Draper Catalogue designation. The star has a yellow hue and is just bright enough to be barely visible to the naked eye with an apparent visual magnitude that fluctuates around 6.29. Based upon parallax measurements, it is located at a distance of 55.8 light years from the Sun. The star is drifting closer with a radial velocity of −8.9 km/s. It is a member of the Eta Chamaeleontis stellar kinematic group. This object is a G-type main-sequence star with a stellar classification of G7V. Klaus G. Strassmeier et al. announced their discovery that HD 111395 is a variable star, in 1997. It was given its variable star designation in 2006. It is a BY Draconis variable that varies in brightness by about 0.10 magnitude over a period of 15.8 days, which is interpreted as the rotation period of the star. (Messina et al. (2003) suspect the actual rotation period may be half that: 7.9 days.) It has an active chromosphere and is a source for X-ray emission. The star is around a billion years old with a projected rotational velocity of 3.8 km/s. It has slightly above solar metallicity − the term astronomers use for the relative abundance of elements other than hydrogen and helium. The mass of the star is 8% greater than the Sun, but it has 93% of the Sun's radius. It is radiating 80% of the luminosity of the Sun from its photosphere at an effective temperature of 5649 K. An infrared excess indicates a cold debris disk is orbiting the star at a distance of 17.48 AU with a mean temperature of 60 K. The disk has an estimated mass of 5.86×10−6 M🜨.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 111395

Start with the simplest possible case. Write down what HD 111395 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 111395 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 111395 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 111395

In research: HD 111395 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 111395 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 111395 is common in secondary-school and first-year university syllabi. It links to neighbouring topics BY Draconis variables, Bright Star Catalogue objects, Circumstellar disks, so understanding it makes those chapters shorter.
In everyday life: Look for HD 111395 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 111395 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 111395 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 111395 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 111395 in simple terms?

HD 111395 is a single, variable star in the northern constellation of Coma Berenices. It has the variable star designation LW Comae Berenices; HD 111395 is the Henry Draper Catalogue designation.

Why does HD 111395 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 111395?

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 111395.