astronomy

V3903 Sagittarii

V3903 Sagittarii 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 V3903 Sagittarii rather than just read about it. In short: V3903 Sagittarii (also known as 11 Sagittarii, or its abbreviation 11 Sgr) is an eclipsing binary star system in the constellation Sagittiarus. It creates an H II region LBN 29 (Sh 2-29) 1,070 parsecs (3,500 light-years) away from the Sun.

Key takeaways

V3903 Sagittarii belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect V3903 Sagittarii to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of V3903 Sagittarii from memory before moving on to harder problems.

Reference excerpt

V3903 Sagittarii (also known as 11 Sagittarii, or its abbreviation 11 Sgr) is an eclipsing binary star system in the constellation Sagittiarus. It creates an H II region LBN 29 (Sh 2-29) 1,070 parsecs (3,500 light-years) away from the Sun. John Flamsteed designated this star the Flamsteed designation 11 Sagittarii, although the designation 11 Sgr is now more often used to refer to the star he designated 1 Sagittarii.

Properties The system consists of two hot main-sequence stars. The spectral types have historically been accepted as O7V and O9V, but the more recent Galactic O-Star Spectroscopic Survey gives a spectral type of O7V(n)z + B0:V:. The system is one of the youngest-known eclipsing binaries, and one of the few containing such massive stars that have not yet filled their roche lobes. Their likely age is around 1.6 million years, and they have current masses of 27 M☉ and 19 M☉. In 1973, Alan William James Cousins announced that the star, which he referred to as HD 165921, varies in brightness. It was given its variable star designation, V3903 Sagittarii, in 1977. The General Catalogue of Variable Stars lists it as a possible hot irregular Orion variable star, but it has been shown to be a detached eclipsing binary system. The two stars are detached, that is they do not fill their roche lobes, which makes it an Algol-type eclipsing variable. The period is one day, 18 hours, 52 minutes. The distance derived from the annual parallax measured by the Hipparcos satellite is around 459 parsecs (1,500 ly), but the distance calculated from the physical properties of the two stars is 1,500 pc. Later measurements have resulted in refined distances estimates of 1,070 pc and 1,200 pc.

References

Illustrations

Worked examples

Example 1 — a first encounter with V3903 Sagittarii

Start with the simplest possible case. Write down what V3903 Sagittarii 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 V3903 Sagittarii 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 V3903 Sagittarii 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 V3903 Sagittarii

In research: V3903 Sagittarii 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 V3903 Sagittarii 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: V3903 Sagittarii is common in secondary-school and first-year university syllabi. It links to neighbouring topics Algol variables, B-type main-sequence stars, Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for V3903 Sagittarii 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “V3903 Sagittarii” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study V3903 Sagittarii in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what V3903 Sagittarii 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 V3903 Sagittarii out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is V3903 Sagittarii in simple terms?

Why does V3903 Sagittarii 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 V3903 Sagittarii?

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 V3903 Sagittarii.