Indus (the Indian) is a faint southern constellation introduced by Dutch cartographer Petrus Plancius in the late 16th century. It was one of 12 southern constellations based on observations made by Dutch navigators during voyages to the Southern Hemisphere.
Although Indus contains no particularly bright stars, it is home to one of the Sun’s closest stellar neighbors, Epsilon Indi, which has a giant planet and two brown-dwarf companions. The constellation also contains several interesting galaxies, including the unusual dust-ringed galaxy NGC 7049.
Where Is Indus and When Can You See It?
Indus is the 49th-largest constellation, covering approximately 294 square degrees of the southern sky. It borders Grus, Microscopium, Octans, Pavo, Sagittarius, Telescopium, and Tucana.
The constellation is best observed during August through October, particularly around September, when it is well positioned in the evening sky. Indus is primarily a Southern Hemisphere constellation. It can be seen from tropical northern latitudes, but is not visible from Britain or most of Europe.
To locate it, begin with the brighter stars of Pavo, particularly Peacock (Alpha Pavonis), and look toward the neighboring region of Indus. Alpha Indi, a third-magnitude orange giant, provides the most useful starting point. Because the remaining stars are considerably fainter, a star chart is helpful for tracing the constellation.
History of the Indus Constellation
Indus was introduced by Petrus Plancius in 1598, using southern star observations gathered during Dutch voyages to the East Indies. It subsequently appeared in Johann Bayer’s influential 1603 star atlas, Uranometria, where it was depicted as a figure carrying spears or arrows.
Unlike many northern constellations, Indus has no established connection with ancient Greek mythology. Its name and depiction reflect European encounters with Indigenous peoples during the Age of Exploration. The precise people intended by the original figure are uncertain, and historical interpretations have suggested regions including southern Africa, Madagascar, and Southeast Asia.
Indus remains one of the 88 constellations officially recognized by the International Astronomical Union.
Notable Stars in Indus
- Alpha Indi – The brightest star in Indus, an orange giant approximately 100 light-years away, shining at magnitude 3.1. It has expanded considerably beyond the Sun’s size as it has evolved away from the main sequence. The star has historically been associated with the name “The Persian.”
- Beta Indi – An orange giant or bright giant approximately 600 light-years away, with an apparent magnitude of 3.7. It is substantially larger and more luminous than the Sun.
- Epsilon Indi – A nearby orange dwarf approximately 11.9 light-years away, shining at magnitude 4.7. Despite being relatively faint, it is one of the closest stellar systems to the Sun and is particularly interesting because of its companions.
- Rho Indi – A yellow subgiant approximately 85 light-years away. It has evolved beyond the main sequence and is also known to host an exoplanet.
- T Indi – A semiregular variable red giant whose brightness changes over time. It can become bright enough to observe with binoculars under suitable conditions.
Epsilon Indi — A Nearby Star With Unusual Companions
Epsilon Indi is one of the most interesting stellar systems in the southern sky. Its primary star, Epsilon Indi A, is a K-type main-sequence star smaller, cooler, and less luminous than the Sun. At approximately 11.9 light-years away, it is among our nearest stellar neighbors.
In 2003, astronomers identified a pair of brown dwarfs associated with the star. Known as Epsilon Indi Ba and Bb, these objects are too small to sustain the stable hydrogen fusion that powers ordinary stars. The two brown dwarfs orbit one another while traveling around Epsilon Indi A at a much greater distance.
The system also contains Epsilon Indi Ab, a giant planet orbiting the primary star. Direct observations by the James Webb Space Telescope have provided important information about this cold planetary companion. Epsilon Indi A also has a notably high proper motion, meaning its position against the background stars changes relatively quickly as it travels through space.
Together, the planet and brown dwarfs make Epsilon Indi a valuable nearby laboratory for studying objects cooler and less massive than ordinary stars.
Notable Deep-Sky Objects in Indus
There are no Messier objects in Indus, but the constellation contains several galaxies of interest.
NGC 7049 — A Galaxy With a Dark Dust Ring
NGC 7049 is a galaxy approximately 100 million light-years away, notable for its striking central dust ring. Its smooth, luminous outer regions resemble those of an elliptical galaxy, while the dark ring surrounding its center gives it characteristics associated with disk galaxies. Hubble Space Telescope images reveal the contrast between the bright stellar halo and the intricate dust structures near the galaxy’s core.
NGC 7049 also contains a population of globular clusters. Its unusual structure may reflect a complicated evolutionary history, potentially involving interactions or mergers with other galaxies.
IC 5152 — A Nearby Irregular Galaxy
IC 5152 is a dwarf irregular galaxy approximately 5.8 million light-years away, just beyond the main concentration of galaxies in the Local Group. Unlike the orderly spiral structure of the Milky Way, IC 5152 has an irregular shape and contains regions of ongoing star formation. Its relatively short distance makes it useful for studying individual bright stars and the evolution of nearby dwarf galaxies.
NGC 7090 — An Edge-On Spiral Galaxy
NGC 7090 is a spiral galaxy approximately 30 million light-years away. From Earth, we see its disk almost edge-on, revealing a flattened band of stars and dust rather than the familiar spiral-arm pattern seen in face-on galaxies.
It has an apparent magnitude around 10.5 and is a challenging but achievable target for experienced amateur observers using suitable telescopes.
Other galaxies within Indus include the elliptical galaxies NGC 7041 and NGC 7029, along with the spiral galaxies NGC 7064 and NGC 7083.