astronomy

NGC 5643

NGC 5643 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 5643 rather than just read about it. In short: NGC 5643 is an intermediate spiral galaxy in the constellation Lupus. Based on the tip of the red-giant branch distance indicator, it is located at a distance of about 40 million light-years (12.5 megaparsecs).

Key takeaways

NGC 5643 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 5643 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 5643 from memory before moving on to harder problems.

Reference excerpt

NGC 5643 is an intermediate spiral galaxy in the constellation Lupus. Based on the tip of the red-giant branch distance indicator, it is located at a distance of about 40 million light-years (12.5 megaparsecs). NGC 5643 has an active galactic nucleus and is a type II Seyfert galaxy.

Observation history The galaxy was first discovered by James Dunlop on May 10, 1826, with his 9-inch reflector telescope, who described it as exceedingly faint. The galaxy was also spotted by John Herschel and added to the General Catalogue of Nebulae and Clusters as number 3572. The galaxy is located only 15 degrees from the galactic plane.

Structure

NGC 5643 is a grand design spiral galaxy, with two well-defined, symmetric arms. In the circumnuclear region, other dust spirals are present, but the two main dust arms are wider. The galaxy is seen nearly face on, at an inclination of ~ 27°.

Active galactic nucleus

The galaxy has a low-luminosity active galactic nucleus of Seyfert 2 type and is also a luminous infrared galaxy. The galaxy has a double-sided diffuse radiojet. The galaxy exhibits an extended emission-line region elongated along a direction close to the radio position angle of 87°±3°. Chris Simpson et al. analysed images takes from the WFPC2 camera of the Hubble Space Telescope in [O III] λ5007 and Hα and found emission extending eastward for at least 1.8 kpc and in the [O III]/Hα map a well-defined V-shaped structure that they identified as the projection of a tridimensional ionisation cone, which shares the same axis with the radio emission. A dust lane perpendicular to this axis obstructs the nucleus from direct view. A disk of material was found when the data cubes of VLT were analysed. It is aligned with the nucleus, circles it, and may provide gas to the active galactic nucleus. The mass of the supermassive black hole has been estimated based on the galaxy stellar velocity dispersion to be 106.4 M⊙. It has been proposed that the gas outflow has led to star formation on two locations on the bar of the galaxy which lie at the location where the gas from the nucleus encounters the dense material of the bar. Based on observations of the galaxy by the XMM Newton telescope in 2009, it was found to have a Compton–thick active galactic nucleus. Also the galaxy emits soft X-rays, mainly from photoionized matter. The presence of the compton-thick column which obstructs the nucleus was confirmed from observations by NuSTAR.

Ultraluminous X-ray source In 2004, Guainazzi et al. detected in the images from XMM-Newton an ultraluminous X-ray source, named NGC 5643 ULX1, located within 0.8 arcminutes from the nucleus. The source outshone the nucleus in X-rays, and if it lies within NGC 5643, its luminosity exceeds 1040 erg/s. Its luminosity is variable. The X-rays could be produced either by an advection dominated disc or a Comptonising corona and the X-ray source is considered to be a black hole of stellar origin of approximately 30 solar masses.

Supernovae Two supernovae have been recorded within the galaxy:

SN 2013aa (Type Ia, mag. 11.9) was discovered by Stuart Parker from New Zealand on 13 February 2013, as part of the Backyard Observatory Supernova Search. It was classified as a Type Ia a few days before maximum brightness. It got as bright as magnitude 11.3, making it the brightest supernova of the year 2013. SN 2017cbv (Type Ia, mag. 16.0451) was discovered by the Distance Less Than 40 Mpc Survey (DLT40) on 10 March 2017. It increased in magnitude from 15.8 to 14.8 within the next day. It got as bright as magnitude 11.5, making it the brightest supernova of the year 2017.

Nearby galaxies NGC 5643 has a satellite dwarf galaxy, ESO 273-014. NGC 5643 is the most prominent member of a small galaxy group that also includes NGC 5530.

References

External links

NGC 5643 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 5643

Start with the simplest possible case. Write down what NGC 5643 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 5643 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 5643 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 5643

In research: NGC 5643 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 5643 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 5643 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1826, Barred spiral galaxies, Discoveries by James Dunlop, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 5643 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 5643 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 5643 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 5643 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 5643 in simple terms?

Why does NGC 5643 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 5643?

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 5643.