astronomy

Messier 109

Messier 109 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 Messier 109 rather than just read about it. In short: Messier 109 (also known as NGC 3992 or the Vacuum Cleaner Galaxy) is a barred spiral galaxy approximately 67.2 ± 23 million light-years away in the northern constellation Ursa Major. M109 can be seen south-east of the star Phecda (γ UMa, Gamma Ursa Majoris).

Key takeaways

Messier 109 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Messier 109 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Messier 109 from memory before moving on to harder problems.

Reference excerpt

Messier 109 (also known as NGC 3992 or the Vacuum Cleaner Galaxy) is a barred spiral galaxy approximately 67.2 ± 23 million light-years away in the northern constellation Ursa Major. M109 can be seen south-east of the star Phecda (γ UMa, Gamma Ursa Majoris).

History Messier 109 was discovered by Pierre Méchain in 1781. Two years later Charles Messier catalogued the object, as an appended object to his publication. Between the 1920s through the 1950s, it was considered that Messier objects over 103 were not official, but later the additions, further referred target objects from Méchain, became more widely accepted. David H. Levy mentions the modern 110 object catalog while Sir Patrick Moore places the limit at 104 objects but has M105 to 109 listed as addenda. By the late 1970s all 110 objects were in common use among astronomers and remain so to this day.

General information This galaxy is the most distant object in the Messier Catalog, followed by M91. M109 has three satellite galaxies (UGC 6923, UGC 6940 and UGC 6969) and possibly more. Detailed hydrogen line observations have been obtained from M109 and its satellites. M109's H I (H one) distribution is regular with a low-level radial extension outside the stellar disc, while in the bar is a central H I hole in the gas distribution. Possibly the gas has been transported inwards by the bar, and because of the emptiness of the hole no large accretion events can have happened in the recent past. M109 is the brightest galaxy in the M109 Group, a large group of galaxies in the constellation Ursa Major that may number over 50.

Supernova One supernova has been observed in M109: SN 1956A (Type Ia, mag. 12.3) was discovered by Howard S. Gates on 8 March 1956, using the 18-inch Schmidt telescope at the Palomar Observatory. It was located 67" east and 9" south of the center of the galaxy.

Gallery

See also List of Messier objects NGC 1300 – a similar barred spiral galaxy

References

External links

"Messier 109". SEDS. Retrieved 2005-08-11.

Messier 109 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images M109

Illustrations

Worked examples

Example 1 — a first encounter with Messier 109

Start with the simplest possible case. Write down what Messier 109 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 Messier 109 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 Messier 109 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 Messier 109

In research: Messier 109 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 Messier 109 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: Messier 109 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1781, Barred spiral galaxies, Discoveries by Pierre Méchain, so understanding it makes those chapters shorter.
In everyday life: Look for Messier 109 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 Messier 109 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Messier 109 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 Messier 109 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Messier 109 in simple terms?

Why does Messier 109 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 Messier 109?

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 Messier 109.