Constellations

Fornax the Furnace and 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. Tucked in a bend of Eridanus the River, Fornax is one of 14 constellations that Nicolas Louis de Lacaille named in the mid-1700s. 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.

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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, is only magnitude 3.9. This star lies about 46 light-years from Earth. The second brightest star, Beta Fornacis, at magnitude 4.4, lies 168 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 at magnitude 4.6 and 357 light-years away.

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 SatelliteTESS found at least three exoplanets orbiting this star in 2019.

Fornax the Furnace Star chart showing brightest stars.
Finder chart for Fornax the Furnace and its brighter stars. Image via IAU/ S&T/ Wikimedia Commons.

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, while the galaxy itself wasn’t discovered for more than 100 years later, by Harlow Shapley in 1938.

Central concentration of 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.
Light smattering of stars at center with brighter stars scattered around.
The Fornax Dwarf galaxy is one of our Milky Way’s neighboring galaxies. It looks almost 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

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: White glow with dark brown blobs and wisps in front blocking some light.
The giant elliptical galaxy NGC 1316 lies in Fornax the Furnace. It’s part of the Fornax Cluster. The NASA/ESA Hubble Space Telescope took this image of the galaxy and its dark dust lanes on March 31, 2005. Image via NASA/ ESA/ Hubble Heritage Team.
Spiral galaxy at lower right, smaller blobs and ovals of galaxies throughout.
View at EarthSky Community Photos. | Mainak Chakraborty in Kolkata, West Bengal, India, took this image of the Fornax Cluster of galaxies on November 26, 2021. Mainak wrote: “The Fornax Cluster is a cluster of galaxies lying at a distance of approximately 62 million light-years. It’s the second richest galaxy cluster within 100 million light-years, after the considerably larger Virgo Cluster. It can be divided into two subclusters: the main one, centered on NGC 1399, and a subgroup 3 degrees to the southwest, centered on the lenticular galaxy NGC 1316. The medium between the galaxies is filled with a hot, rarefied gas that emits x-rays and contains a number of intergalactic stars, some of which have produced novas.” Thank you, Mainak! See an annotated version of his image here.

Hubble Ultra Deep Field

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

Black background with orangish blobs and swirls plus distant pinpricks.
The Hubble Space Telescope took its original Ultra Deep Field image in Fornax in 2003. This image 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 different sized 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.

Blobby purple lines and very many tiny spirals show elements of the largest rotation.
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 (c) 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.

Posted 
December 17, 2021
 in 
Constellations

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