astronomy

OQ 172

OQ 172 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 OQ 172 rather than just read about it. In short: OQ 172 (OHIO Q 172) is a quasar located in the constellation of Boötes. It has a redshift of (z) 3.544, making it one of the most distant quasars at the time of its discovery by astronomers in 1973.

Key takeaways

OQ 172 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect OQ 172 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of OQ 172 from memory before moving on to harder problems.

Reference excerpt

OQ 172 (OHIO Q 172) is a quasar located in the constellation of Boötes. It has a redshift of (z) 3.544, making it one of the most distant quasars at the time of its discovery by astronomers in 1973. This object was the record holder for almost a decade, before being surpassed by PKS 2000-330 in 1982 located at the redshift of (z) 3.78.

Description The source of OQ 172 has a radio spectrum characterized by its spectral peak in the gigahertz domain, making it a gigahertz-peaked spectrum quasar (GPS) or a compact steep spectrum source (CSS). OQ 172 contains a core-jet structure with the radio core itself located in the northern region of the radio emission. This core is found to show a flat spectrum up to > 30 GHz in the rest frame with a steep spectrum above 30 GHz which continues steepening until 1000 GHz, thus confirming there is no buried flat spectrum core within the emission source. The jet of OQ 172 is found to turn almost at an 180° angle with jet emission in the west-southwest direction extending right from the core, eventually bending almost southwards. When reaching 20 mas south of the core, the jet immediately bends once again, this time at 90° and extends towards the east. A further study also shows the jet has three components, one of which is the fastest at a proper motion of 0.13 ± 0.01 mas yr−1. With a mean TB of 15.5 ± 6.4 × 1010 K, this suggests OQ 172 has a highly beamed jet. Very long baseline interferometry radio observations revealed OQ 172 has magnetic fields on parsec scales which rotate the polarization plane of the radio emission originating from both its core and inner jet. Based on the derived rest-frame rotational measurement of RM 40,000 rad m−2, it is found OQ 172 has the highest value amongst other known RM sources. When at 10 mas from the core, the jet's absolute value of RM decreases to <100 rad m−2. Additionally, linear polarized emission has been detected in both components in all five frequencies. The core has low fractional polarization, while the jet components have a higher polarization. A rotational measurement was obtained at 4.8 and 8.3 GHz respectively, showing a high value of 2000 rad m−2 in the innermost region of OQ 172. Towards the outer jet regions, this value drops to 700 rad m−2, quickly decreasing to lower values.

References

External links OQ 172 on SIMBAD OQ 172 on NASA/IPAC Database

Illustrations

Worked examples

Example 1 — a first encounter with OQ 172

Start with the simplest possible case. Write down what OQ 172 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 OQ 172 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 OQ 172 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 OQ 172

In research: OQ 172 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 OQ 172 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: OQ 172 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Active galaxies, Astronomical objects discovered in 1973, Boötes, so understanding it makes those chapters shorter.
In everyday life: Look for OQ 172 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 OQ 172 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OQ 172 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 OQ 172 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OQ 172 in simple terms?

OQ 172 (OHIO Q 172) is a quasar located in the constellation of Boötes. It has a redshift of (z) 3.544, making it one of the most distant quasars at the time of its discovery by astronomers in 1973.

Why does OQ 172 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 OQ 172?

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 OQ 172.