astronomy

PKS 1222+216

PKS 1222+216 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 PKS 1222+216 rather than just read about it. In short: PKS 1222+216 also known as 4C 21.35, is a quasar located in the constellation of Coma Berenices. The redshift of the object is (z) 0.433, estimating the object to be located 4.6 billion light-years from Earth and it was first discovered by astronomers in 1966 as a radio source.

Key takeaways

PKS 1222+216 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PKS 1222+216 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PKS 1222+216 from memory before moving on to harder problems.

Reference excerpt

PKS 1222+216 also known as 4C 21.35, is a quasar located in the constellation of Coma Berenices. The redshift of the object is (z) 0.433, estimating the object to be located 4.6 billion light-years from Earth and it was first discovered by astronomers in 1966 as a radio source. The radio spectrum of PKS 1222+216 is considered as flat, thus the classification of it being a flat-spectrum radio quasar.

Description

Flaring activity PKS 1222+216 is a blazar, mainly being optically violently variable on the electromagnetic spectrum and also described as a very high energy emitter. When first observed in April 2009 it was shown to be in an active phase, with an increasing amount of gamma-ray flux reaching around 4.6 ± 1.6 × 10−7 photons cm−2 s−1. By December 15, 2009, the source's flux had reached 3.4 ± 0.5 × 10−6 photons cm−2 s−1, marking this as an increase by a factor of 40. Two powerful gamma-ray flares were detected from PKS 1222+216 by various observations in April and June 2010. The object displayed a broken power-law form with observed spectra breaks near the ranges between 1 and 3 GeV photons. The optical polarimetric observations also noted the variability of the source in both polarization and position angle, with a detected decrease in brightness levels of 0.34 magnitude between 19 and 22 June in V band. Following the flare of April 2010, the source exhibited an immense increase in near-infrared flux. In 2014 PKS 1222+216 underwent several more flaring periods. When detected, both flares (Flare A and Flare B) were shown to be accompanied by two subflares, occurring within a time span of three days. The subflare of Flare A displayed a slow rising trend, reaching a maximum at MJD (56699 ± 0.5), subsequently followed by a rapid decrease. Subflare 2 of Flare A, displayed an increase to its maximum peak, before displaying a slow decay time. The flux for Flare A has been estimated as 3.2 ± 0.42 × 10−6 photon cm−2 s−1. The subflares of Flare B on the other hand, showed a rapid rise time, subsequently followed by a slow decay time lasting 0.6 days.

Radio Source The structure of the source of PKS 1222+216, is compact and highly distorted with an angular extent of 17 arcseconds. When imaged with the Very Large Array (VLA) on kiloparsec scales, it has a bright radio core surrounded by radio emission that is 100 kiloparsecs in extent. A secondary component is seen extending 12 arcseconds from the core. There is a jet present in the source, originating in the northeast before abruptly bending eastwards and ending in a hotspot located 60 kiloparsecs from the core. This jet is also superluminal, with at least five jet knots moving at fast speeds between the ranges of 9c and 22c. Observations also found two of these knots were shown ejecting during quasar flaring periods.

Quasi-periodic oscillation and supermassive black hole mass In 2022, PKS 1222+216 was shown undergoing a quasi-periodic oscillation with a period of around 420 days based on optical photometric and polarimetric data observations conducted for 10 years. This is explained by a blob feature moving in helical motion inside a jet. The central supermassive black hole mass for the quasar has been estimated as 6 × 108 M☉ based on a virial method of its broad emission lines.

References

Illustrations

Worked examples

Example 1 — a first encounter with PKS 1222+216

Start with the simplest possible case. Write down what PKS 1222+216 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 PKS 1222+216 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 PKS 1222+216 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 PKS 1222+216

In research: PKS 1222+216 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 PKS 1222+216 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: PKS 1222+216 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 4C objects, Active galaxies, Astronomical objects discovered in 1966, so understanding it makes those chapters shorter.
In everyday life: Look for PKS 1222+216 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 PKS 1222+216 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PKS 1222+216 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 PKS 1222+216 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PKS 1222+216 in simple terms?

Why does PKS 1222+216 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 PKS 1222+216?

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 PKS 1222+216.