astronomy

MRC 2011−298

MRC 2011−298 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 MRC 2011−298 rather than just read about it. In short: MRC 2011−298 is an elliptical galaxy with an active galactic nucleus, located in the constellation of Sagittarius. It is located 2.1 billion light-years away from Earth.

Key takeaways

MRC 2011−298 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MRC 2011−298 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MRC 2011−298 from memory before moving on to harder problems.

Reference excerpt

MRC 2011−298 is an elliptical galaxy with an active galactic nucleus, located in the constellation of Sagittarius. It is located 2.1 billion light-years away from Earth. MRC 2011−298 is the brightest cluster galaxy in the galaxy cluster, Abell 3670 and classified as a dumbbell galaxy, an optical system with two galactic nuclei separated by 7″, corresponding to ≃17 kpc according to the adopted cosmology, with similar magnitude and a common stellar halo. The galaxy is known to have an ellipticity of ε = 0.28 and a position angle of PA = 24° that is measured from north to east.

Characteristics MRC 2011−298 lies in the rich galaxy cluster which is located at redshift z = 0.142 . The cluster has an angular scale of 1″ = 2.4 kpc, and with a luminosity distance of DL = 645 Mpc. MRC 2011−298 has a peculiar shape which its radio source was observed at 5.5 GHz using the Very Large Array (VLA). Instead of being classified as either a FRI and FRII radio galaxy, the galaxy belongs to a class of X-shaped radio galaxies; it exhibits a pair of bright lobes in north to south direction with a pair of weak wings in the east going from east to west direction. These wings are oriented with an angle of about 90°, thus giving the structure its cross-like shape. Like other X-shaped radio galaxies, MRC 2011−298 has primary lobes with jets containing hotspots, but the wings does not hosts jets. The flux density of the radio lobes in MRC 2011−298 is Slobes = 294 ± 15 mJy, with east and the west wings have a flux density of SEw = 32 ± 2 mJy and SWw = 23 ± 1 mJy, respectively. The total length of the lobes is found to be llobes ≃ 60″ ≃ 145 kpc, whereas the wings is lEw ≃ 75″ ≃ 180 kpc and lWw ≃ 60″ ≃ 145 kpc wide. Its ratio between the projected lengths of the wings and lobes of MRC 2011−298 is 2.8. Thanks to researchers, the radio jets in MRC 2011−298 are found to be characterized by a curvature and an S-shaped structure. But no hotspots are present. Further observations suggests the wings are very faint (S < 5 mJy). The eastern one appears as diffuse emission, while the western wing is better defined. As for the north and south jets, the flux density is confirmed to SSj = 17 ± 1 mJy and SNj = 11.1 ± 0.3 mJy, respectively, with similar lengths of lSj ≃ lNj ≃ 18″ ≃ 40 kpc, suggesting MRC 2011−298 to be an FRI-type XRG measured by 1.4 GHz of P1.4 = (1.7 ± 0.1) × 1025 W Hz−1. The radio power of the galaxy is consistent with the radio power of typical XRGs, intermediate between that of FRIs and FRIIs.

Hydrodynamical model It is suggested the jets in MRC 2011−298 are aligned with the major axis of a high ellipticity galaxy. This causes stronger environment gas pressure along the major axis with respect to the minor axis. The backflow plasma originating from the hotspots in MRC 2011−298 is found to redirect towards the minor axis, where the minimum resistance of the gas allows the formation of the wings. In the buoyant backflow model, the wings plasma of MRC 2011−298 are led by the buoyancy force which evolves at subsonic speeds. In this variant of this model, strong backflows forms an over-pressured cocoon, with respect to the surrounding gas. This ejects plasma outflows at supersonic speed along the steepest pressure gradient (i.e. the minor axis), to produce more extended wings. From three-dimensions numerical simulations, this suggests a supersonic origin and a subsonic evolution of the wings inside the galaxy.

Galaxy merger Further observations found MRC 2011−298 contains gas present inside a stellar shell deflecting the radio jets and causing the wings to be formed. Such evidence found, suggests MRC 2011−298 might have gone a galaxy merger with a disk galaxy triggering its active black hole and a system of stellar shells. These stellar shells are form of rotating arc-shaped structures roughly found in ~10% of local elliptical galaxies, that are aligned with their optical major axis. Looking through jet interaction in Centaurus A and the stellar shells, finds a similar phenomenon in X-shaped radio galaxies where they contain traces of neutral and molecular hydrogen with an estimated mass of MH ≃ 4 × 107 M☉ and average density of nH ≃ 4 × 10−2 cm−3. MRC 2011−298 is known to have a high supermassive black hole mass, which is responsible for reorienting the jets making primary lobes evolve along the new direction, with its wings as fossil emissions from previous jets. This phenomenon is caused after the coalescence with another supermassive black hole or during the interaction between a binary black hole or unstable regions of its accretion disk. From traces of stellar shells and high black hole mass, this indicates MRC 2011−298 is the end product caused by several galaxy mergers, hence sharing common characteristics of dominant cluster galaxies.

References

Illustrations

Worked examples

Example 1 — a first encounter with MRC 2011−298

Start with the simplest possible case. Write down what MRC 2011−298 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 MRC 2011−298 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 MRC 2011−298 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 MRC 2011−298

In research: MRC 2011−298 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 MRC 2011−298 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: MRC 2011−298 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Active galaxies, Elliptical galaxies, Principal Galaxies Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for MRC 2011−298 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 MRC 2011−298 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MRC 2011−298 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 MRC 2011−298 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MRC 2011−298 in simple terms?

MRC 2011−298 is an elliptical galaxy with an active galactic nucleus, located in the constellation of Sagittarius. It is located 2.1 billion light-years away from Earth.

Why does MRC 2011−298 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 MRC 2011−298?

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 MRC 2011−298.