astronomy

HD 164270

HD 164270 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 164270 rather than just read about it. In short: HD 164270, (also known as WR 103 or V4072 Sagittarii), is a Wolf–Rayet star of the carbon subtype (WC) located in the constellation of Sagittarius. The star exhibits low-amplitude photometric and radial velocity variations with a period of 1.754 days, interpreted as arising from a single-line spectroscopic binary system containing a low-mass companion, possibly a neutron star.

Key takeaways

HD 164270 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 164270 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 164270 from memory before moving on to harder problems.

Reference excerpt

HD 164270, (also known as WR 103 or V4072 Sagittarii), is a Wolf–Rayet star of the carbon subtype (WC) located in the constellation of Sagittarius. The star exhibits low-amplitude photometric and radial velocity variations with a period of 1.754 days, interpreted as arising from a single-line spectroscopic binary system containing a low-mass companion, possibly a neutron star. It has experienced occasional dramatic fading events of nearly 1 magnitude, though these are not definitively linked to eclipses.

Observation As a late-type carbon-rich Wolf–Rayet star, HD 164270 displays broad emission lines dominated by carbon and oxygen in its spectrum, indicative of a strong stellar wind. Models accounting for line blanketing and wind clumping yield an effective temperature of approximately 48,000 K, a luminosity of about 79,400 times that of the Sun (log(L/L☉) ≈ 4.9), and a mass-loss rate of roughly 10−5 M☉/yr for a volume filling factor of 0.1. The terminal wind velocity is around 1,400 km/s. Abundances derived from optical and mid-infrared diagnostics include C/He ≈ 0.2 and O/He ≈ 0.01 by number, with neon and sulfur abundances elevated relative to solar values (Ne/He ≈ 2.2×10−3 and S/He ≈ 5.1×10−5).

Variability HD 164270 displays cyclic photometric variations with a period of 1.75404 days and an amplitude of ~0.03 magnitude in the visible (increasing at shorter wavelengths), manifesting as a double-wave light curve per cycle. Emission-line radial velocities vary with a single wave per cycle and low amplitude (~20–30 km/s), consistent with orbital motion in a binary system. In addition to these short-period variations, the star has undergone rare, deep fading events, including drops of nearly 1 magnitude observed in June 1980 and September 1909. The 1980 event showed no color change, and archival plate analysis limits possible periods for recurrence to 17.7, 35.4, or 70.8 years. These events may represent partial eclipses by a large, cool companion or could arise from alternative mechanisms such as a precessing accretion disk influenced by a third body, or nonradial pulsations. No definitive eclipses have been confirmed in the short-period binary orbit.

References

Illustrations

Worked examples

Example 1 — a first encounter with HD 164270

Start with the simplest possible case. Write down what HD 164270 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 164270 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 164270 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 164270

In research: HD 164270 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 164270 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 164270 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Henry Draper Catalogue objects, Hipparcos objects, Objects with variable star designations, so understanding it makes those chapters shorter.
In everyday life: Look for HD 164270 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 164270 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 164270 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 164270 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 164270 in simple terms?

Why does HD 164270 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 164270?

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 164270.