How big is Gomez's Hamburger?

Gomez's Hamburger is a young star surrounded by a large disk of gas and dust, which is seen almost exactly edge-on from Earth. By the most recent estimate of its distance, the disk is about 1,800 astronomical units (au), or 270 billion kilometers, across. One au is about 150 million kilometers, Earth's average distance from the Sun. The nickname comes from its shape: a dark band between two bright layers, like a patty in a bun.

Size

The size given is the width of the disk's gas, which astronomers map from the faint radio glow of carbon monoxide molecules. On the sky the disk spans about 13 arcseconds, where an arcsecond is 1/3,600 of a degree. Turning that angle into a true width needs the distance, and the distance has been hard to measure because the disk hides the star.

Studies in 2015 and 2020 used a distance of about 800 light-years, where a light-year is the distance light travels in a year. At that distance, the gas disk is about 3,000 au (450 billion kilometers) across. In 2026 a team led by Charles Law estimated the distance again, from maps of the dust between the stars and from the positions of nearby young stars. They found it closer, about 450 light-years, which makes the disk about 1,800 au across.

The disk is also thick. Its gas reaches up to about 350 au above and below its middle. Even at the new, smaller size, it is one of the largest disks of its kind found as of 2026.

Size comparisons

The disk's radius, about 900 au, is about the same as the distance from the Sun to the farthest point of Sedna's orbit, about 937 au.
The disk is about 30 times as wide as the orbit of Neptune, the outermost planet.
If Neptune's orbit were shrunk to the width of a basketball, the disk would be about 7 meters (24 feet) across.
The disk's radius is about five times the distance from Earth to Voyager 1, the most distant spacecraft, in September 2026.

A disk where planets form

In 1987, astronomers classified Gomez's Hamburger as an old star near the end of its life. NASA's release of a Hubble Space Telescope image in 2002 described it that way too. In 2008, observations of its gas showed that the gas circles the central star the way planets orbit the Sun. That marked it as a young star with a protoplanetary disk, a disk of gas and dust from which planets can form.

The central star has about 2.2 times the mass of the Sun. In the southern half of the disk, about 280 au from the star, sits a dense clump of gas called GoHam b, holding at least several times the mass of Jupiter. Astronomers think it may be a giant planet in the earliest stage of forming, though that has not been confirmed.

Why it looks like a hamburger

The disk is tipped only about 4 degrees away from exactly edge-on as seen from Earth. Dust in the middle of the disk blocks the star's light and forms the dark "patty". Above and below it, starlight reflects off dust in the disk's upper layers and forms the two bright "buns". A. Gómez, of the Cerro Tololo Inter-American Observatory, first noticed the object on a photographic plate in 1985, which is why the nickname carries his name.