astronomy

NGC 2273

NGC 2273 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 2273 rather than just read about it. In short: NGC 2273 is a barred spiral galaxy located in the constellation Lynx. It is located at a distance of about 95 million light years from Earth, which, given its apparent dimensions, means that NGC 2273 is about 100,000 light years across.

Key takeaways

NGC 2273 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 2273 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 2273 from memory before moving on to harder problems.

Reference excerpt

NGC 2273 is a barred spiral galaxy located in the constellation Lynx. It is located at a distance of about 95 million light years from Earth, which, given its apparent dimensions, means that NGC 2273 is about 100,000 light years across. It was discovered by Nils Dunér on September 15, 1867.

Characteristics

NGC 2273 has a multiring structure. The galaxy has an inner ring and two outer pseudorings formed by two sets of spiral arms. The galaxy is seen with an inclination of 41 degrees. The galaxy hosts about 1.1×109 M☉ of hydrogen gas (HI), with most of it lying at the outer pseudoring. The galaxy also hosts large amounts of molecular gas, as indicated by the CO lines, which is regarded as an indicator of active star formation. The total infrared luminosity of the galaxy is 1010.25 L☉. The galaxy has a bar whose radius is 40 arcseconds. Observations of the central 20 arcseconds of the galaxy by the Hubble Space Telescope showed spiral arms that corresponded to the inner ring. The central ovoid of the galaxy was found to feature a bar-like structure and two arc structures that form a partial nuclear ring. Its emission is associated with the presence of HII regions. Around the nucleus lies a dusty ring-like structure, with a radius of 7 arcseconds, better seen at its northwest part. Another dusty ring is observed with 20 arcseconds radius.

Nucleus Based on the emission lines that are present in its spectrum, the nucleus of NGC 2273 has been characterised as active and it has been categorised as a type II Seyfert galaxy. Also, a water kilomaser has been detected in the nuclear region of the galaxy. It could be created either by the active nucleus or by a prominent site of star formation. Observations by BeppoSAX, XMM Newton, and Chandra X-Ray Observatory suggested that the nucleus of NGC 2273 is obscured by a Compton thick column, with high column density, estimated to be 1.1×1024 cm−2 as measured by ASCA, or 1.5×1024 cm−2 as measured by Suzaku. The harder X-Rays manage to get through and are dominated by reflection from cold material, as the Fe-K line indicates. The spectrography of the nuclear regions is weakly polarised, more prominent in H-alpha. The broad X-ray spectrum of NGC 2273 has been found to be composed of a thermal or scattered soft component, a reflected component, and an absorbed power law component. The 2–10 keV X-ray flux of the galaxy is estimated to be 1.7×1042 ergs−1. The nucleus also emits radiowaves. The radio source has been found to be linear and is composed of two unequal radio features separated by about 170 parsecs. These two radio features have been identified as radio jets. A linear jet-like feature extending for 2 arcseconds east of the nucleus was observed in [O III] λ5007 images. It is aligned with the radio jets and is possibly of nuclear origin. The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 2273 is estimated to be between (7.5±0.4)×106 M☉ based on kinematics of the water maser circumnuclear disk. The disk appears warped.

Nearby galaxies NGC 2273 is the brightest galaxy in a galaxy group known as the NGC 2273 group. Other members of the group include the galaxies NGC 2237B and UGC 3504. NGC 2237B lies 40 arcminutes to the south.

See also NGC 1386 - a similar Seyfert galaxy NGC 3081 - a similar multiring Seyfert galaxy

References

External links

NGC 2273 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 2273

Start with the simplest possible case. Write down what NGC 2273 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 2273 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 2273 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 2273

In research: NGC 2273 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 2273 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 2273 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1867, Barred spiral galaxies, Discoveries by Nils Christoffer Dunér, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 2273 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study NGC 2273 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 2273 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 2273 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 2273 in simple terms?

Why does NGC 2273 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 2273?

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 2273.