astronomy

V420 Aurigae

V420 Aurigae 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 V420 Aurigae rather than just read about it. In short: V420 Aurigae is a high-mass star with an inferred compact companion. Closely orbiting each other every 0.8 days, they are a source of X-ray emission.

Key takeaways

V420 Aurigae belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect V420 Aurigae to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of V420 Aurigae from memory before moving on to harder problems.

Reference excerpt

V420 Aurigae is a high-mass star with an inferred compact companion. Closely orbiting each other every 0.8 days, they are a source of X-ray emission. These coordinates were identified as an X-ray source using the Uhuru satellite in 1978, then associated with the star BD+37°1160 by Vito Francesco Polcaro and associates in 1990. The star was found to be a variable star in the visible part of the spectrum, from the Hipparcos data, and was given the variable star designation V420 Aurigae, in 1999. The spectrum of the star shows rapid variation in the lines of singly-ionized iron and Balmer line emission, with these varying on a time scale of less than 300 seconds. This lends support to the presence of a compact companion. The system displays an infrared excess, suggesting it has an orbiting circumstellar envelope of gas and possibly dust. The system appears to be positioned at the center of an irregular, wispy nebula that was detected in the infrared band. One of the two filaments in this nebula appears to be connected with the system.

References

Further reading Norci, L.; et al. (December 2006), "Is the X-ray Transient HD 34921 (4U 0515+38) a B[e] Star?", Stars with the B[e] Phenomenon. ASP Conference Series, Vol. 355, Proceedings of the Conference Held 10-16 July, 2005, at the Isle of Vlieland, The Netherlands, vol. 355, San Francisco: Astronomical Society of the Pacific, p. 289, Bibcode:2006ASPC..355..289N. Polcaro, V. F.; et al. (2007), St.-Louis, Nicole; Moffat, Anthony F.J. (eds.), "The Very Unusual HMXRB HD 34921", Massive Stars in Interactive Binaries, ASP Conference Series 367, vol. 367, San Francisco: Astronomical Society of the Pacific, p. 471, Bibcode:2007ASPC..367..471P. Waagen, Elizabeth O. (October 2016), "Observations of V420 Aur (HD 34921) needed to support spectroscopy", AAVSO Alert Notice 554, vol. 554, p. 1, Bibcode:2016AAN...554....1W. Polcaro, V. F.; et al. (2006), Meurs, E. J. A.; Fabbiano, G. (eds.), "The Be/X-ray transient HD34921", Populations of High Energy Sources in Galaxies Proceedings of the 230th Symposium of the International Astronomical Union, Held in Dublin, Ireland 15-19 August 2005, vol. 1, Cambridge: Cambridge University Press, pp. 49–50, Bibcode:2006IAUS..230...49P, doi:10.1017/S1743921306007824.

External links HIC 25114 Image V420 Aurigae

Illustrations

Worked examples

Example 1 — a first encounter with V420 Aurigae

Start with the simplest possible case. Write down what V420 Aurigae 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 V420 Aurigae 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 V420 Aurigae 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 V420 Aurigae

In research: V420 Aurigae 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 V420 Aurigae 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: V420 Aurigae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Auriga, B-type subgiants, Be stars, so understanding it makes those chapters shorter.
In everyday life: Look for V420 Aurigae 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 V420 Aurigae in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what V420 Aurigae 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 V420 Aurigae out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is V420 Aurigae in simple terms?

V420 Aurigae is a high-mass star with an inferred compact companion. Closely orbiting each other every 0.8 days, they are a source of X-ray emission.

Why does V420 Aurigae 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 V420 Aurigae?

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 V420 Aurigae.