science

Virgo Cluster

Virgo Cluster is a science 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 Virgo Cluster rather than just read about it. In short: The Virgo Cluster is a cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the Virgo constellation. Comprising approximately 1,300 (and possibly up to 2,000) member galaxies, the cluster forms the heart of the larger Virgo Supercluster, of which the Local Group (containing the Milky Way galaxy) is a member.

Key takeaways

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

Reference excerpt

The Virgo Cluster is a cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the Virgo constellation. Comprising approximately 1,300 (and possibly up to 2,000) member galaxies, the cluster forms the heart of the larger Virgo Supercluster, of which the Local Group (containing the Milky Way galaxy) is a member. The Local Group actually experiences the mass of the Virgo Supercluster as the Virgocentric flow. It is estimated that the Virgo Cluster's mass is 1.2×1015 M☉ out to 8 degrees of the cluster's center or a radius of about 2.2 Mpc. Many of the brighter galaxies in this cluster, including the giant elliptical galaxy Messier 87, were discovered in the late 1770s and early 1780s and subsequently included in Charles Messier's catalogue of non-cometary fuzzy objects. Described by Messier as nebulae without stars, their true nature was not recognized until the 1920s. The cluster extends across approximately 8 degrees centered in the constellation Virgo. Some of its most prominent members can be seen with binoculars and small telescopes, while a 6-inch telescope will reveal about 160 of the cluster's galaxies on a clear night. Its brightest member is the elliptical galaxy Messier 49.

Characteristics The cluster is a fairly heterogeneous mixture of spiral and elliptical galaxies. As of 2004, it is believed that the spiral galaxies of the cluster are distributed in an oblong prolate filament, approximately four times as long as it is wide, stretching along the line of sight from the Milky Way. The elliptical galaxies are more centrally concentrated than the spiral galaxies. The first example of an ultra-diffuse galaxy was also found in the central core of the cluster in 1984. The cluster is an aggregate of at least three separate subclumps: Virgo A, centered on M87, a second centered on the galaxy M86, and Virgo B, centered on M49, with some authors including a Virgo C subcluster, centered on the galaxy M60 as well as a Low Velocity Cloud (LVC) subclump, centered on the large spiral galaxy NGC 4216. The giant elliptical galaxy M87 contains a supermassive black hole, whose event horizon was observed by the Event Horizon Telescope Collaboration in 2019. Virgo A is the dominant subclump; its mass of approximately 1014 M☉ is approximately ten times larger than the other two subclumps. It contains a mixture of elliptical, lenticular, and spiral galaxies which are generally gas-poor,

The three subgroups are in the process of merging to form a larger single cluster, and are surrounded by other smaller galaxy clouds, mostly composed of spiral galaxies, known as N Cloud, S Cloud, and Virgo E that are in the process of infalling to merge with them, plus other farther isolated galaxies and galaxy groups (like the galaxy cloud Coma I) that are also attracted by the gravity of Virgo to merge with it in the future. This strongly suggests the Virgo cluster is a dynamically young cluster that is still forming. Nearby aggregations known as M Cloud, W Cloud, and W' Cloud seem to be background systems independent of the main cluster. The large mass of the cluster is indicated by the high peculiar velocities of many of its galaxies, sometimes as high as 1,600 km/s with respect to the cluster's center. The Virgo cluster lies within the Virgo Supercluster, and its gravitational effect slows down the nearby galaxies. The large mass of the cluster has the effect of slowing down the recession of the Local Group from the cluster by approximately ten percent. Many of the galaxies contained within the Virgo cluster undergo ram pressure stripping, where pressure from the dense intracluster medium efficiently removes molecular gas from the cluster's galaxies. This gas removal can eventually lead to the quenching of star formation in these galaxies.

Intracluster medium As with many other rich galaxy clusters, Virgo's intracluster medium is filled with a hot, rarefied plasma at temperatures of 30 million kelvins that emits X-Rays. Within the intracluster medium (ICM) are found a large number of intergalactic stars (up to 10% of the stars in the cluster), including some planetary nebulae. It is theorized that these were expelled from their home galaxies by interactions with other galaxies. The ICM also contains some globular clusters, possibly stripped off dwarf galaxies, and even at least one star formation region.

Galaxies

Below is a table of bright or notable objects in the cluster and their subcluster. In some cases a galaxy may be considered to be in a different subcluster by other researchers (sources:)

Column 1: The name of the galaxy. Column 2: The right ascension for epoch 2000. Column 3: The declination for epoch 2000. Column 4: The blue apparent magnitude of the galaxy. Column 5: The galaxy type: E=Elliptical, S0=Lenticular, Sa,Sb,Sc,Sd=Spiral, SBa,SBb,SBc,SBd=Barred spiral, Sm,SBm,Irr=Irregular. Column 6: The angular diameter of the galaxy (arcminutes). Column 7: The diameter of the galaxy (thousands of light years). Column 8: The recessional velocity (km/s) of the galaxy relative to the cosmic microwave background. Column 9: Subcluster where the galaxy is located.

Fainter galaxies within the cluster are usually known by their numbers in the Virgo Cluster Catalog, particularly members of the numerous dwarf galaxy population.

See also Virgo III Groups Coma Cluster – another large, nearby cluster of galaxies Eridanus Cluster Fornax Cluster – a smaller nearby cluster of galaxies Norma Cluster List of galaxy clusters

Notes

References

Further reading Kashibadze, Olga G.; Karachentsev, Igor D.; Karachentseva, Valentina E. (2020). "Structure and kinematics of the Virgo cluster of galaxies". Astronomy & Astrophysics. 635: A135. arXiv:2002.12820. Bibcode:2020A&A...635A.135K. doi:10.1051/0004-6361/201936172.

External links The Virgo Cluster at An Atlas of the Universe, map (and table) of the 160 largest galaxies California Institute of Technology site on Virgo cluster. The Virgo Cluster of Galaxies, SEDS Messier pages Partial Virgo cluster centered on M87 (Dark Atmospheres) Binggeli, B.; Sandage, A.; Tammann, G. A. (1985). "Studies of the Virgo cluster. II. A catalog of 2096 galaxies in the Virgo cluster area". The Astronomical Journal. 90: 1681. Bibcode:1985AJ.....90.1681B. doi:10.1086/113874.

Illustrations

Worked examples

Example 1 — a first encounter with Virgo Cluster

Start with the simplest possible case. Write down what Virgo Cluster claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Virgo Cluster 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 Virgo Cluster 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 Virgo Cluster

In research: Virgo Cluster appears in science 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 Virgo Cluster 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: Virgo Cluster is common in secondary-school and first-year university syllabi. It links to neighbouring topics Coma Berenices, Virgo (constellation), Virgo Cluster, so understanding it makes those chapters shorter.
In everyday life: Look for Virgo Cluster 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 Virgo Cluster in 20 minutes

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

Frequently asked questions

What is Virgo Cluster in simple terms?

Why does Virgo Cluster matter?

Because it connects several science 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 Virgo Cluster?

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 Virgo Cluster.