Antlia (the Air Pump) is a faint southern constellation introduced by French astronomer Nicolas-Louis de Lacaille during the 18th century. Named after a scientific instrument rather than a mythological figure, it contains no particularly bright stars and is easily overlooked in the night sky.
Its brightest star, Alpha Antliae, is an orange giant approximately 365 light-years away, shining at around magnitude 4.3. Although Antlia has no Messier objects, it contains several interesting galaxies, including the impressive spiral NGC 2997 and the distant Antlia Galaxy Cluster.
Where Is Antlia and When Can You See It?
Antlia is the 62nd-largest of the 88 recognized constellations, covering approximately 239 square degrees of the southern sky. It lies south of Hydra, near Centaurus, Pyxis, and Vela.
The constellation is best observed during March and April, particularly from the Southern Hemisphere. It is also visible from some northern locations, although it appears relatively low above the southern horizon. Because Antlia has no distinctive pattern of bright stars, a detailed star chart is helpful for identifying it.
Who Created the Antlia Constellation?
Antlia was introduced by Nicolas-Louis de Lacaille, who mapped the southern sky from the Cape of Good Hope in South Africa between 1751 and 1753. He originally named it Antlia Pneumatica, meaning the Pneumatic or Air Pump, after an instrument used to remove air from an enclosed chamber.
Air pumps became important scientific tools during the 17th and 18th centuries, helping researchers investigate atmospheric pressure and the properties of gases. Lacaille named most of his newly introduced southern constellations after scientific instruments, tools, and other objects, reflecting the growing importance of experimental science.
Unlike ancient constellations, Antlia has no traditional Greek or Roman mythology.
Notable Stars in Antlia
Antlia contains no stars brighter than fourth magnitude, but several are interesting examples of evolved stars.
Image Credit: Torsten Bronger Alpha Antliae – The constellation’s brightest star, an orange giant approximately 365 light-years away with an apparent magnitude around 4.3. It has expanded to roughly 50 times the Sun’s radius and is hundreds of times more luminous.
- Epsilon Antliae – An orange giant approximately 700 light-years away, shining at magnitude 4.5. Like Alpha Antliae, it has expanded considerably as it has evolved beyond the main sequence.
- Iota Antliae – An orange giant approximately 200 light-years away with an apparent magnitude of 4.6.
- Theta Antliae – A multiple-star system containing stars of different temperatures and brightnesses.
- U Antliae – An evolved carbon-rich star surrounded by a remarkable shell of gas and dust expelled during an earlier phase of its life. Observations of this shell help astronomers understand how aging stars return material to interstellar space.
Deep-Sky Objects in Antlia
Antlia contains no Messier objects, but several of its galaxies are of considerable interest to astronomers.
NGC 2997 — A Grand-Design Spiral Galaxy
NGC 2997 is a spectacular spiral galaxy approximately 25 million light-years away, with an apparent magnitude around 10.6.
It is classified as a grand-design spiral, meaning it has two prominent, well-defined spiral arms rather than a fragmented or irregular pattern.
Its central region contains a yellowish population of older stars, while the spiral arms are rich in young blue stars and glowing pink clouds of hydrogen gas.
These clouds mark regions where new stars are forming, making NGC 2997 a particularly attractive target for astrophotographers.
The galaxy can be detected with amateur telescopes under dark southern skies, although photographs reveal considerably more detail than visual observations.
The Antlia Galaxy Cluster
The Antlia Cluster, also known as Abell S0636, is a large collection of galaxies approximately 130 million light-years away. It contains hundreds of galaxies, including giant elliptical galaxies, smaller spiral systems, and numerous dwarf galaxies. Two particularly prominent members are NGC 3258 and NGC 3268, giant elliptical galaxies surrounded by extensive populations of globular star clusters.
The Antlia Cluster is one of the relatively nearby rich galaxy clusters, making it useful for studying galaxy evolution and the gravitational interactions that occur within clusters.
NGC 3125 — A Starburst Galaxy
NGC 3125 is a relatively small galaxy undergoing an intense period of star formation. Its bright central regions contain young, massive stars whose powerful radiation and stellar winds influence the surrounding gas. Astronomers study starburst galaxies such as NGC 3125 to understand how large numbers of stars can form over comparatively short periods.
Other Galaxies in Antlia
Other galaxies of interest include NGC 3244, a spiral galaxy with active star-forming regions, and IC 2560, a spiral galaxy whose central region contains an active galactic nucleus. These objects are generally faint and are better suited to larger telescopes or long-exposure astrophotography.
How to Find Antlia
Antlia lies beneath the long, winding constellation Hydra, between the southern constellations Pyxis and Centaurus. The constellation is most conveniently observed from southern latitudes during March and April, when it appears higher in the evening sky.
Its faint stars can be difficult to distinguish from the surrounding star field, so observers should use a detailed chart and seek out a dark observing location. For amateur astronomers with suitable telescopes, NGC 2997 is one of Antlia’s most rewarding deep-sky targets.