IC 1101 Facts for Kids

Quick facts for kids IC 1101
June 1995 image of IC 1101 taken by the Hubble Space Telescope
Observation data (J2000 epoch)
Constellation	Virgo
Right ascension	15^h 10^m 56.1^s
Declination	+05° 44′ 41″
Redshift	0.078054±0.000027
Helio radial velocity	22,419 km/s (13,931 mi/s)
Distance	354.0 ± 24.8 Mpc (1,154.6 ± 80.9 million ly)Template:Hub
Group or cluster	Abell 2029
Type	cD; S0-
Apparent dimensions (V)	1'.2 × 0'.6
Apparent magnitude (V)	13.22
Other designations
UGC 9752, PGC 54167, A2029-BCG
See also: Galaxy, List of galaxies

IC 1101 is an incredibly huge galaxy found in the center of a group of galaxies called the Abell 2029 cluster. It's known as a supergiant lenticular galaxy, which means it has a shape that's a mix between a flat disc and a round ball. This galaxy is one of the largest ever discovered, stretching across an amazing distance. Inside, it holds one of the biggest supermassive black holes known in the universe! IC 1101 is located about 354.0 megaparsecs (1.15 billion light-years) away from Earth. An astronomer named William Herschel first spotted it on June 19, 1790.

Exploring IC 1101: A Giant Galaxy
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Exploring IC 1101: A Giant Galaxy

How We Discovered IC 1101

IC 1101 was first seen by the German-British astronomer William Herschel in 1790. Later, it was added to a list of galaxies called the Index Catalogue. This is where it got its common name, IC 1101.

Scientists have studied this galaxy for many years. In 1964, they noticed it might be giving off radio waves, similar to other galaxies. In 1978, astronomer Alan Dressler studied the galaxy cluster where IC 1101 lives. He then focused on IC 1101 itself, learning more about its movements and features.

Over the years, many telescopes and surveys have looked at IC 1101. The Hubble Space Telescope took detailed pictures of its center. These studies helped scientists understand its huge core and the giant black hole within it.

What Makes IC 1101 Special?

Its Shape and Type

IC 1101 imaged by the Sloan Digital Sky Survey

IC 1101 is classified as a supergiant elliptical or lenticular galaxy. It is the brightest galaxy in its cluster, Abell 2029. Scientists sometimes call it A2029-BCG, which means "Brightest Cluster Galaxy." Its exact shape is still debated. It might look like a flat disc, but we see it from Earth in a way that makes it appear very wide.

Inside the Galaxy: Stars and Black Hole

Like most large galaxies, IC 1101 is full of stars. Many of these stars are very old, some even seven billion years older than our Sun. These old stars give the galaxy a golden-yellow color.

At the very center of IC 1101 is a very bright source of radio waves. This is likely caused by an ultramassive black hole. This black hole is one of the most massive ever found! It could be 40 to 100 billion times the mass of our Sun. This makes it an "overmassive" black hole, pushing the limits of how big black holes can get.

IC 1101 also has a lot of dark matter around it. Dark matter is a mysterious substance that we can't see, but it adds a lot of weight to the galaxy. The galaxy doesn't seem to be forming many new stars right now. It also doesn't have much dust in its central area.

In 2017, scientists found that IC 1101 has the largest core of any known galaxy. Its core is about 4.2 kpc (14 thousand ly) wide. This is much larger than the cores of other big elliptical galaxies. Scientists think that when black holes merged to form this galaxy, they might have thrown stars out of the core, making it so large and empty.

The main part of IC 1101 is aligned in a northeast to southwest direction. Its core and main body are well-aligned. However, the outer part, called the halo, is slightly twisted. This twist might be why it's classified as a lenticular galaxy.

IC 1101 imaged by the 9th data release of the Legacy survey.

How Big is IC 1101?

IC 1101 is considered a truly enormous galaxy. It has a huge, spread-out halo of light. This light comes from intracluster light (ICL). ICL is made of stars that are no longer tied to any single galaxy. These "free-flying" stars are often found around the brightest galaxies in a cluster, like IC 1101.

Scientists measure the size of galaxies in different ways. Early measurements suggested its main part was about 65 kpc (210 thousand ly) wide. However, its faint outer halo stretches much further, up to 600 kpc (2 million ly)! This makes IC 1101 one of the largest and most luminous galaxies in the universe.

More recent measurements, using a standard method called D₂₅, show its diameter to be about 123.65 kiloparsecs (403,000 ly). Another measurement using infrared light suggests it could be even larger, around 169.61 kiloparsecs (553,000 ly). Both of these numbers confirm it as one of the biggest galaxies known.

How Far Away is IC 1101?

Measuring the exact distance to IC 1101 has been tricky. Different methods have given different results over time. Scientists use something called redshift to figure out how far away galaxies are. Redshift tells us how much light from a galaxy has been stretched as it travels through the expanding universe.

Early estimates in 1980 put its distance at about 262.0 Mpc (855 million ly). However, based on modern calculations and the current understanding of the universe's expansion, the accepted distance to IC 1101 is about 354.0 megaparsecs (1.2 billion light-years). This means its light takes 354 million years to reach us!

How IC 1101 Grew So Large

Scientists believe that IC 1101 became so massive by "eating" other galaxies. At the center of the Abell 2029 cluster, there aren't many other bright galaxies. This suggests that IC 1101 absorbed them as it grew.

The way IC 1101's core looks, and the structure of its halo, suggest it has gone through many galactic mergers. It might have merged with 10 or even more galaxies over its lifetime. The smooth appearance of its halo suggests that these mergers happened very early in the cluster's history.