Sunny Side Up: New Image of the Fried Egg Nebula Reveals a Rare Yellow Hypergiant Star


A new look at the Fried Egg Nebula has revealed one of the rarest classes of stars in the Universe, a yellow hypergiant. This “sunny-side-up” view shows for the first time a huge dusty double shell surrounding this huge star.

“This object was known to glow brightly in the infrared but, surprisingly, nobody had identified it as a yellow hypergiant before,” said Eric Lagadec from the European Southern Observatory, who led the team that produced the new images.

And there’s good reason to keep an eye on this star: it will likely soon die an explosive death, and will be one of the next supernova explosions in our galaxy.

The monster star, IRAS 17163-3907 has a diameter about a thousand times bigger than our Sun. At a distance of about 13,000 light-years from Earth, it is the closest yellow hypergiant found to date and new observations show it shines some 500,000 times more brightly than the Sun. The total mass of this star is estimated to be roughly twenty times that of the Sun.

The star and its shells resemble an egg white around a yolky center, hence, the nickname of the Fried Egg Nebula – which is much easier to say than IRAS 17163-3907.

The observations of the star and the discovery of its surrounding shells were made using the VISIR infrared camera on the VLT. The pictures are the first of this object to clearly show the material around it and reveal two almost perfectly spherical shells.

Astronomers say that if the Fried Egg Nebula were placed in the center of the Solar System, Earth would lie deep within the star itself and the planet Jupiter would be orbiting just above its surface. The much larger surrounding nebula would engulf all the planets and dwarf planets and even some of the comets that orbit far beyond the orbit of Neptune. The outer shell has a radius of 10,000 times the distance from the Earth to the Sun.

Yellow hypergiants are in an extremely active phase of their evolution, undergoing a series of explosive events — this star has ejected four times the mass of the Sun in just a few hundred years. The material flung out during these bursts has formed the extensive double shell of the nebula, which is made of dust rich in silicates and mixed with gas.

Source: ESO

15 Replies to “Sunny Side Up: New Image of the Fried Egg Nebula Reveals a Rare Yellow Hypergiant Star”

    1. There’s a reason for that. As big as the VLT is, it’s still a ground based telescope and gas to deal with the Earth’s atmosphere. Adaptive optics can only do so much. Maybe Hubble can get a clear shot in the future.

      1. I was only joking; this photo doesn’t have the same clarity as most others that we are used to, and the reason is provided below by GeorgesMouth.

      2. I’m serious, if I stare at this picture, it looks to me like it’s shrinking. Ohhhh, maybe I need to get my eyes checked out.

  1. Yellow hypergiants could not only go supernova but hypernova! That would add some extremely energetic bacon jets to that Fried Egg and would make a nice breakfast for observers from Earth.

    PS. Can someone call CSI to enhance resolution of that image?

  2. Hmm… IRAS 17163-3907 is located in Scorpius. I’ve been poking around the i-net a bit but wasn’t able to find any magnitude estimates, visible or absolute concerning this star. It WAS found by an infrared sensitive *.sat.. but usually magnitudes are estimated and released as part of any data set as a matter of course.

    1. A 1989 study of IRAS 17163-3907 (aka Hen 1379) gave photometric magnitudes of B=17.1 and V=13.0 (Johnson UBV):…225..417L&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf

      IRAS 17163-3907 would appear much brighter visually, but for the estimated 6-9 magnitudes of absorption, given in the present paper:

      [SIMBAD gives an infrared K mag of 2.4!]

      1. Thank you for looking this up and providing the links. A Visible magnitude of 13.0 puts this odd critter well within the reach of amateur astronomers and has no doubt sparked continuing interest by AAVSO members?

        I have a newly kindled interest in variable stars as I am reading all three volumes of Burnhams Celestial Handbook – a gift from a neighbor who saw me using my telescope(s). The set given to him as a Christmas present and subsequently sat unread on his bookshelf for years…. they were brand new and unopened!

        Pg. 1653 Vol. III mentions NCG 6337 at 17189s3825 epoch 1950. Obviously when I finish my 12.5 newt I will need updated references. I looked it up and found that there actually is an effort to update this work but that effort is being held up by legal wranglings? Too bad.. an updated version with the latest co-ords and images would be GREAT!

      2. SIMBAD, a great resource for astrodata and papers on a plethora of objects, gives an alternate designation for IRAS 17163-3907 as NSV 21444:

        An AAVSO search for NSV 21444 lists this object as a long-period variable with a magnitude range of V=12.7-13.5 and custom finder/comparison charts should also be available there:

        As to Burnhams Celestial Handbook, I remember picking up sections of this book in the early 70’s with holes punched in the pages for use in a ring-binder. Later I acquired the Dover hardcover editions and they are now heavily annotated with updates and observations I have added over the years. A highly recommended work (and revisions and updates, as you noted, would be very desirable). A treasure trove for visual OR armchair astronomers (and it makes great cloudy-night browsing material).

        Two other refs I find indispensible are the Deep Sky Field Guide for the Uranometria 2000.0 2nd ed atlas (this covers only non-stellar deep-sky objects). Additionally, Sky Catalog 2000.0 vol 2, contains detailed info on variable and multiple stars as well as thousands of non-stellar deep-sky objects.

        …..Oh, and good luck with your Newt.

      3. Of the 131 astronomy bookmarks in my computer, this one (SIMBAD) will no doubt become one of the most well used!

        Thanks again! And thanks for all the sane and well informed comments you’ve made in these pages…

      4. Glad to be of help to a fellow observer. While I usually hunt non-stellar deep sky objects (galaxies, nebulae, clusters & the like) I also enjoy observing colorful double & multiple stars, carbon stars and the occasional cataclysmic variable, nova or supernova (2011fe!)

  3. The material around the star is referred to as spherical in shape, based on what, couldn’t it be two rings?

    Perhaps more interesting then that, what is the band of stuff between the two layers above the star?! Interaction with interstellar space? An object in orbit? What was the exposure time?

  4. Love the CSI quip, Martin! So can anyone explain how a star with 20 times the mass of our sun can get so big? Why is it so huge? Why doesn’t it condense? It would have to be the density of a sponge! Is that enough to support fusion? Did it not form the same traditional way?
    C’mon, smarties, fill us in.

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