astronomy

NGC 3227

NGC 3227 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 NGC 3227 rather than just read about it. In short: NGC 3227 is an intermediate spiral galaxy that is interacting with the dwarf elliptical galaxy NGC 3226. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies.

Key takeaways

NGC 3227 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NGC 3227 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 3227 from memory before moving on to harder problems.

Reference excerpt

NGC 3227 is an intermediate spiral galaxy that is interacting with the dwarf elliptical galaxy NGC 3226. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster. Sir William Herschel already recognised them as a 'double nebula' and they were jointly listed as Holm 187 in the Catalogue of Double and Multiple Galaxies and as Arp 94 in the Atlas of Peculiar Galaxies. Amateur telescopes can discern them but require magnification of about 100 times. They are situated 50′ east of the well-known double star system Gamma Leonis (i.e. Algieba).

Nucleus NGC 3227 contains a Seyfert nucleus, a type of active galactic nucleus (AGN). Such Seyfert nuclei typically contain supermassive black holes. This object has an estimated mass of 1.4+1.0−0.6×107 M☉. As is typical of many AGN, the nucleus of NGC 3227 has been identified as a source of variable X-ray emission. This variability occurs on time scales ranging from a few hours to a few months. The variability may be caused by variations in the density or ionization of gas and dust near the AGN that absorb the X-ray emission. A substantial amount of the X-ray-absorbing gas may lie within 0.4 parsec (1.3 light-years) of the nucleus. An observed change in the shape of the X-ray spectrum in 2000 and 2001 suggests that some of the X-ray absorbing gas is located within 10–100 light-days of the nucleus. The luminosity of the nucleus reached a maximum in 1977 when evidence suggesting long-lived one-sided or two-sided gas streams was obtained. X-ray radiation of the central accretion disc is reprocessed in one to two days to be re-emitted in the optical spectrum. Infra-red light emission from the hot dust torus lags optical light emission from the nucleus by about 20 days in NGC 3227. The temperature of the dust torus is estimated at 1500 K to 1800 K in NGC 3227 and similar galaxies. This galaxy was studied by the Multicolor Active Galactic Nuclei Monitoring 2m telescope.

Supernova One supernova has been observed in NGC 3227: SN 1983U (Type Ia, mag. 12) was discovered by Vladimir Pronik on 4 November 1983.

See also List of NGC objects (3001–4000)

References Catalogue of Double and Multiple Galaxies, Erik Holmberg, 1937 A catalogue of dwarf galaxy candidates around interacting galaxies, Astron. Astrophys., Suppl. Ser., 129, 455-462 (1998) - May(I) 1998, Deeg, H.J. et al. Long-term variability of the optical emission lines in the nuclear spectrum of the Seyfert galaxy NGC 3227, Active Galaxies Newsletter, No 98, Pronik I., Metik L., May 2005 Reverberation Measurements of the Inner Radius of the Dust Torus in Nearby Seyfert 1 Galaxies, M. Suganuma et al., Astrophysical Journal, vol 639, March 2006

External links

Glen Youman's Astrophotos of NGC 3226 and NGC 3227 Cosmic Voyages webpage on NGC 3226 and NGC 3227 Spitzer observations of the interacting galaxy pair Long-term variability of the optical emission lines in the nuclear spectrum of the Seyfert galaxy NGC 3227, Pronik et al., Active Galaxies Newsletter, No. 98 Reverberation Measurements of the Inner Radius of the Dust Torus in Nearby Seyfert 1 Galaxies, Suganuma et al., ApJ, March 2006, vol. 639

NGC 3227 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Illustrations

Worked examples

Example 1 — a first encounter with NGC 3227

Start with the simplest possible case. Write down what NGC 3227 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 NGC 3227 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 NGC 3227 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 NGC 3227

In research: NGC 3227 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 NGC 3227 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: NGC 3227 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arp objects, Astronomical objects discovered in 1784, Intermediate spiral galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 3227 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 NGC 3227 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 3227 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 NGC 3227 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 3227 in simple terms?

Why does NGC 3227 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 NGC 3227?

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 NGC 3227.