Fornax the Furnace: A dim constellation with galaxies galore

Sky chart showing Fornax the Furnace.
Fornax the Furnace lies within one of the bends of Eridanus the River. It passes overhead for those in the Southern Hemisphere on December evenings.

Fornax the Furnace lies high in the Southern Hemisphere sky on December evenings. In fact, it’s tucked in a bend of the constellation Eridanus the River. None of the stars in Fornax is particularly bright, but the constellation does hold some wonderful gems in its darker depths: at least six star systems with exoplanets, the Fornax Dwarf galaxy (a satellite galaxy of the Milky Way), the Fornax Cluster of galaxies, a cosmic filament showing the largest rotation in the universe and the amazing Hubble Ultra Deep Field image. By the way, Fornax is one of 14 constellations that Nicolas Louis de Lacaille named in the mid-1700s.

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Fornax the Furnace and its stars

Deep in the Southern Hemisphere, Fornax the Furnace is a devilish constellation to find because of its dim stars. Its brightest star, Alpha Fornacis, has a magnitude of only 3.9. This star lies about 46 light-years from Earth. The second brightest star, Beta Fornacis, with a magnitude of 4.4, lies 169 light-years away. Sometimes people point to a third star of Fornax in order to trace out a flattened triangle in this region of space. The third brightest star is Nu Fornacis with magnitude 4.6, 357 light-years away.

So far, scientists have found six star systems in Fornax to be harboring planets. One of the stars, HR 858 at magnitude 6.3, is just barely visible to the unaided eye for those with good eyesight. The Transiting Exoplanet Survey Satellite TESS found at least three exoplanets orbiting this star in 2019.

Fornax the Furnace star chart with stars in black on white and brightest stars labeled.
Here’s a finder chart for Fornax the Furnace and its brightest stars. Image via IAU/ S&T/ Wikimedia Commons (CC BY 3.0).

Fornax Dwarf, the satellite galaxy

One of the satellite galaxies of the Milky Way lies in the direction of Fornax the Furnace. The Fornax Dwarf is an elliptical collection of stars with six notable globular clusters. One of its globular clusters, NGC 1049, was discovered by John Herschel on October 19, 1835. But the galaxy itself wasn’t discovered until more than 100 years later, by Harlow Shapley in 1938.

Dense central concentration of bright white stars, becoming more diffuse at the edges.
The Hubble Space Telescope took this image of the Fornax Dwarf’s globular cluster NGC 1049 on November 20, 2014. Image via ESA.
Misty, faint, glowing oblong with scattered foreground stars.
The Fornax dwarf galaxy is one of our Milky Way’s neighboring galaxies. As you can tell, it looks ethereal with its dim, diffuse form against the darkness of space. This image came from data from the Digitized Sky Survey 2. Image via ESO.

Galaxies clusters in Fornax the Furnace

Also, one of the closest galaxy clusters to our Milky Way is the Fornax Cluster. It lies 62 million light-years away in the direction of Fornax and spills over into Eridanus the River. The brightest galaxy in the cluster, NGC 1316, shines at magnitude 8.5, meaning that you can pick it up with binoculars from under dark skies. NGC 1316, which also goes by the name Fornax A, is the fourth brightest radio source in the sky.

Fornax the Furnace galaxy: Roundish, white glowing patch in dark sky with dark brown blobs and wisps in front blocking some light.
The giant elliptical galaxy NGC 1316 lies in Fornax the Furnace. It is also part of the Fornax Cluster. The Hubble Space Telescope observed the galaxy and its dark dust lanes on March 31, 2005. Image via NASA/ ESA/ Hubble Heritage Team.

Hubble Ultra Deep Field

Since this is an “empty” region of sky, giving us a view into the wider universe with few obstructions, the Hubble Space Telescope aimed in the direction of Fornax to take an image of the early universe in 2003. The Hubble Ultra Deep Field shows a small piece of the universe packed with galaxies, looking back in space and time as far as 13 billion years ago.

Black background with myriads of oval or round orangish blobs ranging from small to pinprick sized.
The Hubble Space Telescope took its original Ultra Deep Field image in Fornax in 2003. Shown here is an improved version taken in 2012. The new image revealed a population of distant galaxies at redshifts between 9 and 12. Image via ESO.
Black background filled with very many small-to-tiny dots and ovals in shades of light blue to orange and white.
The MUSE instrument on ESO’s Very Large Telescope looked at the same region of sky as the Hubble Ultra Deep Field. MUSE measured the distances to 1,600 galaxies, including 72 that Hubble didn’t see when it viewed this slice of space. ESO released this image on November 29, 2017. Image via ESO.

Largest rotation in the universe

The galaxies in our universe are strung together in long filaments and webs, creating the grand structure of the cosmos. Scientists have detected that one enormous filament of galaxies is rotating. These corkscrewing galaxies, located in the direction of Fornax, display the largest rotation in the universe.

Long, straight, fuzzy purple line with bright white blobs along it, and very many tiny spirals.
This is a rotating strand in the cosmic web in the direction of Fornax the Furnace. Scientists released the image in April 2021, and it looks back to a time 2 billion years after the Big Bang. Each point of light is a galaxy. You can see a filament between the galaxies, tracing the path of the cosmic web. Read more about this image. Image via ESO / NASA/ Roland Bacon et al.

Bottom line: Fornax the Furnace is a constellation in the Southern Hemisphere that appears as a few dim stars to the unaided eye but is harboring galaxies, from one orbiting the Milky Way to some at the edge of the universe.

December 17, 2023

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