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Messier 106

Messier 106 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 106 rather than just read about it. In short: Messier 106 (also known as NGC 4258) is an intermediate spiral galaxy in the constellation Canes Venatici. It was discovered by Pierre Méchain in 1781.

Messier 106 — main illustration
Messier 106 — illustration

Key takeaways

  • Messier 106 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 106 to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Messier 106 from memory before moving on to harder problems.

Reference excerpt

Messier 106 (also known as NGC 4258) is an intermediate spiral galaxy in the constellation Canes Venatici. It was discovered by Pierre Méchain in 1781. M106 is at a distance of about 22 to 25 million light-years away from Earth. M106 contains an active nucleus classified as a Type 2 Seyfert, and the presence of a central supermassive black hole has been demonstrated from radio-wavelength observations of the rotation of a disk of molecular gas orbiting within the inner light-year around the black hole. NGC 4217 is a possible companion galaxy of Messier 106. Besides the two visible arms, it has two "anomalous arms" detectable using an X-ray telescope.

Characteristics M106 has a water vapor megamaser (the equivalent of a laser operating in microwave instead of visible light and on a galactic scale) that is seen by the 22-GHz line of ortho-H2O that evidences dense and warm molecular gas. Water masers are useful for observing nuclear accretion disks in active galaxies. The water masers in M106 enabled the first case of a direct measurement of the distance to a galaxy, thereby providing an independent anchor for the cosmic distance ladder. M106 has a slightly warped, thin, almost edge-on Keplerian disc which is on a subparsec scale. It surrounds a central area with mass 4×107 M☉. It is one of the largest and brightest nearby galaxies, similar in size and luminosity to the Andromeda Galaxy. The supermassive black hole at the core has a mass of (3.9±0.1)×107 M☉. M106 has also played an important role in calibrating the cosmic distance ladder. Before, Cepheid variables from other galaxies could not be used to measure distances since they cover ranges of metallicities different from the Milky Way's. M106 contains Cepheid variables similar to both the metallicities of the Milky Way and other galaxies' Cepheids. By measuring the distance of the Cepheids with metallicities similar to our galaxy, astronomers are able to recalibrate the other Cepheids with different metallicities, a key fundamental step in improving quantification of distances to other galaxies in the universe.

Supernovae Two supernovae have been observed in M106:

SN 1981K (Type II, mag. 17) was reported by E. Hummel and verified by Paul Wild by examining archival photos dated 3 November 1981. SN 2014bc (Type II, mag. 14.8) was discovered by the PS1 Science Consortium 3Pi survey on 19 May 2014.

See also List of Messier objects Canes II Group

References

External links

StarDate: M106 Fact Sheet Spiral Galaxy M106 at SEDS Messier pages Messier 106 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NGC 4258: Mysterious Arms Revealed Spiral Galaxy Messier 106 (NGC 4258) at the astro-photography site of Takayuki Yoshida Nemiroff, R.; Bonnell, J., eds. (19 March 2011). "Messier 106". Astronomy Picture of the Day. NASA. Nemiroff, R.; Bonnell, J., eds. (3 May 2012). "Messier 106". Astronomy Picture of the Day. NASA. Messier 106 at Constellation Guide

Illustrations

Messier 106 illustration
Messier 106: Composite image features X-rays from Chandra (blue), radio waves from the VLA (purple), optical data from Hubble (yellow and blue), and infrared with Spitzer (red). Two anomalous arms, which are not visible at optical wavelengths, appear as purple and blue emissions.
Composite image features X-rays from Chandra (blue), radio waves from the VLA (purple), optical data from Hubble (yellow and blue), and infrared with Spitzer (red). Two anomalous arms, which are not visible at optical wavelengths, appear as purple and blue emissions.

Worked examples

Example 1 — a first encounter with Messier 106

Start with the simplest possible case. Write down what Messier 106 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 106 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 106 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 106

In research
Messier 106 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 106 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 106 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1781, Canes II Group, Canes Venatici, so understanding it makes those chapters shorter.
In everyday life
Look for Messier 106 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 106 in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Messier 106 means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Messier 106 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Messier 106 in simple terms?

Messier 106 (also known as NGC 4258) is an intermediate spiral galaxy in the constellation Canes Venatici. It was discovered by Pierre Méchain in 1781.

Why does Messier 106 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 106?

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 106.

Tags

  • Astronomical objects discovered in 1781
  • Canes II Group
  • Canes Venatici
  • Discoveries by Pierre Méchain
  • Intermediate spiral galaxies
  • Messier objects
  • NGC objects
  • Principal Galaxies Catalogue objects
  • Seyfert galaxies
  • UGC objects

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