Tycho’s Supernova (3C 10, SN 1572) is a supernova remnant located approximately 8,000 to 9,800 light-years away in the constellation Cassiopeia. The supernova event that produced the remnant was discovered in early November 1572 and independently recorded as a “new star” by observers around the world. The supernova was brighter than any star in the night sky and remained visible for over a year.
Tycho’s Supernova has all but faded from view in the optical band but appears bright in X-rays. It has an angular size of 8 arcminutes and an expansion rate of 11-12% per year, or 9,000 km/s. Astronomers have determined an average forward shock speed of 4,000 – 5,000 km/s for the remnant.
Observations of the supernova remnant indicate that SN 1572 was a type Ia supernova, triggered by an accreting white dwarf in a binary system. Type Ia supernovae occur when a white dwarf star pulls material from a binary companion. When it reaches the critical mass of 1.44 solar masses (the Chandrasekhar limit), the white dwarf reignites and undergoes a runaway reaction that releases enough energy to trigger a supernova event. At its peak, a type Ia supernova can outshine an entire galaxy.
More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of the progenitor star produced a shock wave moving outward into the surrounding interstellar gas, and another, reverse shock wave moving back into the expanding stellar debris. This Chandra image of Tycho reveals the dynamics of the supernova event in exquisite detail. The outer shock has produced a rapidly moving shell of high-energy electrons (blue), and the reverse shock has heated the expanding debris to millions of degrees (red and green). There is evidence from the Chandra data that these shock waves may be responsible for some of the cosmic rays – ultra-energetic particles – that pervade the Galaxy. Image credit: Chandra X-ray Observatory Center, Smithsonian Institution (PD)
While most studies accept a single progenitor, some have proposed that Tycho’s Supernova was triggered by a merger of two white dwarfs.
Type Ia supernovae have a consistent peak luminosity because the critical mass at which a white dwarf goes out as a supernova is fixed. Combined with the supernova’s visual magnitude and the known extinction of 1.86 magnitudes, astronomers derived a distance of 3.8 kpc for the remnant of SN 1572 in 2008. More recent estimates give a range of 2.5 and 3 kpc (between 8,000 and 9,800 ly).
The light of the historic supernova SN 1572 reached Earth soon after November 2, 1572. By November 11, the luminous supernova outshone Jupiter and peaked at magnitude -4 around November 16. At the peak, it was similar in brightness to Venus and could be seen in the daytime sky for about two weeks.
The supernova was visible to the unaided eye throughout 1573. By March 1574, it had slowly faded and disappeared from view.
As with many supernova remnants, the Tycho supernova remnant, as it’s known today (or “Tycho,” for short), glows brightly in X-ray light because shock waves — similar to sonic booms from supersonic aircraft — generated by the stellar supernova heat the stellar debris up to millions of degrees. In its two decades of operation, NASA’s Chandra X-ray Observatory has captured unparalleled X-ray images of many supernova remnants. Chandra reveals an intriguing pattern of bright clumps and fainter areas in Tycho. What caused this thicket of knots in the aftermath of this supernova? Did the event itself cause this clumpiness, or was it something that happened afterward? This 2019 image of Tycho from Chandra is providing clues. To emphasize the clumps in the image and the three-dimensional nature of Tycho, scientists selected two narrow ranges of X-ray energies to isolate material (silicon, colored red) moving away from Earth, and moving towards us (also silicon, colored blue). The other colors in the image (yellow, green, blue-green, orange and purple) show a broad range of different energies and elements, and a mixture of directions of motion. In this new composite image, Chandra’s X-ray data have been combined with an optical image of the stars in the same field of view from the Digitized Sky Survey. Credit: X-ray: NASA/CXC/RIKEN & GSFC/T. Sato et al; Optical: DSS (PD)
Tycho Brahe
SN 1572 is called Tycho’s Supernova, Tycho’s Nova, or Tycho’s Star because Danish astronomer Tycho Brahe wrote an extensive work about it in 1572, titled De nova et nullius aevi memoria prius visa stella (“Concerning the Star, new and never before seen in the life or memory of anyone”).
When it appeared in the region of Cassiopeia’s familiar W asterism, Tycho’s new star challenged the old Aristotelian dogma of the eternal and unchanging celestial sphere that moves in uniform circular motion. Copernicus had published his model of the universe only three decades earlier, in 1543, placing the Sun rather than Earth at its centre. Even though the heliocentric model revolutionized astronomy, the budding science still went hand in hand with astrology and superstition. The guest star was seen as omen, and monarchs turned to astronomers to interpret its sudden appearance.
Horoscope for the Supernova of 1572 (labeled: “Nova stella”) by Tycho Brahe (1573)
Tycho Brahe’s observations of SN 1572 showed that the “new star” was located far beyond the Moon. This challenged the old dogma that the universe beyond the Sun and the planets did not change. While the Danish astronomer did not understand the nature of supernovae, his accurate observations set new standards for astronomical measurements, which later allowed his assistant Johannes Kepler to develop his laws of planetary motion.
Tycho Brahe was a key figure in 16th century astronomy and is considered the greatest astronomer before the invention of the telescope. The first telescope was designed several decades after the discovery of SN 1572, in the early 1600s. Tycho himself did not live to see it. He used sextants, mural quadrants, lenses, and armillary spheres for his observations.
While his observations and inventions pushed astronomy forward, Tycho Brahe did not adopt the Copernican model himself. He believed that the Sun, Moon and the stars revolved around the Earth, while the five solar system planets known at the time revolved around the Sun.
Tycho Brahe’s illustration of SN 1572
Facts
The remnant of Tycho’s Supernova was discovered by British astronomers Robert Hanbury Brown and Cyril Hazard during radio observations at Jodrell Bank Observatory in England in 1952.
Baldwin and Edge confirmed the position of the remnant and provided a more accurate position using the Cambridge Radio Telescope in 1957. The radio remnant is catalogued as 2C 34 in the second Cambridge Catalogue of Radio Sources and 3C 10 in the third Cambridge Catalogue of Radio Sources.
In the early 1970s, the Uhuru X-ray observatory detected an X-ray source that was subsequently designated Cepheus X-1 (Cep X-1). The source corresponds to the Tycho SNR. The remnant appears bright in X-ray light because the shock wave from the supernova heats the surrounding material to millions of degrees.
The optical component of Tycho’s Supernova was discovered as a very faint nebula on photographic plates obtained at the Palomar Observatory in the 1960s.
In 2004, astronomers identified the companion of the progenitor white dwarf. A team led by Pilar Ruiz-Lapuente, Department of Astronomy, University of Barcelona, found a Sun-like star of the spectral type G0-G2 that was moving at more than three times the mean velocity of other stars at the same distance. The researchers identified the star as the surviving companion of the progenitor star of SN 1572 and named it Tycho G.
Before the supernova, the companion could have been a main sequence star or a subgiant. At the time of discovery, it presented as a subgiant with lower surface gravity than main sequence stars but higher than red giants. The scientists proposed that the centre of the supernova event was 2.6 arcseconds north of the present location of Tycho G. Based on the data in the Gaia Data Release 2 (Gaia DR2), Tycho G lies approximately 6,400 light-years away.
These images show the location of a suspected runaway companion star to a titanic supernova witnessed in the year 1572 by the great Danish astronomer Tycho Brahe and other astronomers of that era. This discovery provides the first direct evidence supporting the long-held belief that Type Ia supernovae come from binary star systems containing a normal star and a burned-out white dwarf star. When the dwarf ultimately goes out by being overfuelled by the companion star, the companion is slung away from the progenitor star. The Hubble Space Telescope played a key role by precisely measuring the surviving star’s motion against the sky background. Image credit: NASA, ESA, CXO and P. Ruiz-Lapuente (University of Barcelona) (PD)
Tycho’s Nova was confirmed as a type Ia supernova by an international team of astronomers from the Max Planck Institute for Astronomy in Germany, the University of Tokyo, and the European Space Agency (ESA) in 2008. The researchers obtained an optical spectrum of the supernova near maximum brightness from a light echo more than four centuries after the supernova event.
A 2025 study proposed that Tycho’s Supernova occurred within a planetary nebula, a remnant of a low- to intermediate mass star that expelled its gaseous layers when it reached the end of its life. Theoretical astrophysicist Noam Soker identified two opposite protrusions (“ears”) projected on the remnant’s main shell. These ear structures are believed to have been part of the old planetary nebula’s structure before the supernova event. The SNIP (supernova inside a planetary nebula) scenario was originally suggested by Dickel & Jones in 1985. More recent studies have strongly indicated that Tycho’s Nova was interacting circumstellar material and surrounded by a dense wall.
The ears of the Tycho remnant are similar to those seen in Kepler’s Supernova in Ophiuchus, which was also considered as a supernova inside a planetary nebula. The supernova remnants SNR G299-2.9 in the constellation Norma and SNR G1.9+0.3 in Sagittarius have similar features.
While Tycho’s Supernova looks spherical, studies have found a large-scale asymmetry. The remnant has an elongated structure and is slightly tilted. Astronomers have identified asymmetries in the distribution of silicon and sulfur, as well as blueshifted knots projected more in the northern region of the remnant and redshifted knots more concentrated in the southern portion. In other words, the blueshifted (approaching) side of the remnant appears north and the redshifted (receding) side appears south.
This image shows iron debris in Tycho’s supernova remnant. The site of the supernova is shown, as inferred from the motion of the possible companion to the progenitor white dwarf. The position of material stripped off the companion star by the supernova event, and forming an X-ray arc, is shown by the white dotted line. This structure is most easily seen in an image showing X-rays from the arc’s shock wave. Finally, the arc has blocked debris from the supernova creating a “shadow” in the debris between the red dotted lines, extending from the arc to the edge of the remnant. Image: NASA/CXC/Chinese Academy of Sciences/F. Lu et al. (PD)
Tycho’s Supernova was probably first spotted by the German astronomer Wolfgang Schüler of Wittenberg on November 6, 1572. Like everyone else, Schüler believed that this was a new star in the constellation Cassiopeia.
Tycho Brahe spotted the supernova several days later, on November 11, from his observatory at Herrevad Abbey in Denmark (modern-day Sweden).
He wrote, “I noticed that a new and unusual star, surpassing the other stars in brilliancy, was shining almost directly above my head; and since I had, from boyhood, known all the stars of the heavens perfectly, it was quite evident to me that there had never been any star in that place of the sky, even the smallest, to say nothing of a star so conspicuous and bright as this. I was so astonished of this sight that I was not ashamed to doubt the trustworthiness of my own eyes. But when I observed that others, on having the place pointed out to them, could see that there was really a star there, I had no further doubts. A miracle indeed, one that has never been previously seen before our time, in any age since the beginning of the world.”
Tycho’s Supernova may have been the bright star that also made an impression on the young William Shakespeare, who would have seen the supernova as a boy. The star is mentioned by the character Bernardo in the first scene of Hamlet (“When yond same star that’s westward from the pole/Had made his course to illume that part of heaven/Where it now burns…”).
A couple of centuries later, the supernova inspired the young Edgar Allan Poe to write the poem “Al Aaraaf.” Poe identified the new star with Al Aaraaf, a star that was a medium between paradise and hell.
Tycho’s Supernova is one of only eight known historical supernovae that were visible to the unaided eye and documented in historical records. The other visible supernovae were SN 185 (associated with the remnant RCW 86) near Alpha Centauri, on the border between Centaurus and Circinus, SN 393 (associated with RX J1713.7-3946) in Scorpius, SN 1006 (associated with SNR G327.6+14.6) in Lupus, the Crab Supernova (SN 1054, associated with the Crab Nebula) in Taurus, SN 1181 (associated with Pa 30) in Cassiopeia, Kepler’s Supernova (SN 1604) in Ophiuchus, and SN 1987A in the Large Magellanic Cloud in Dorado.
Tycho’s Nova is not the only famous supernova remnant in Cassiopeia. Cassiopeia A, which appears in the region between Caph and Zeta Cephei, was the last supernova in the Milky Way that was visible to the unaided eye. It is also the youngest known supernova in our galaxy. It was discovered in the late 1940s.
The Medulla Nebula (CTB 1) also lies in Cassiopeia. It is one of the largest known supernova remnants in the sky. It is associated with the high-velocity Cannonball Pulsar.
Comparison of Type Ia Supernovas This 4-panel compares the Chandra image of DEM L238 with the Chandra image of 3 Type Ia supernova remnants located in the Milky Way. The X-ray emission for Kepler’s remnant contains a bright central region similar to DEM L238, while the X-ray emission for Tycho’s remnant and SN 1006 are generally much more uniform. These results suggest that the stars that went out and caused the DEM L238 and Kepler supernova remnants were much younger than the stars that produced the Tycho and SN 1006 remnants. Credit: NASA/CXC (PD)
Location
Tycho’s Supernova appears in the region above Cassiopeia’s W, along the imaginary line extended from Tiansi (Gamma Cassiopeiae) to Alfirk (Beta Cephei) in the neighbouring Cepheus constellation. The nearest relatively bright star is the blue supergiant Cexing (Kappa Cassiopeiae).
The open clusters NGC 133 and NGC 146 appear in the same area, between the supernova remnant and Kappa Cassiopeiae.
Tycho’s Supernova is too faint to be observed in amateur telescopes. At declination +64°, it never rises for observers south of the latitude 26° S.
Tycho’s Supernova location, image: Stellarium
Tycho’s Supernova – SN 1572
| Constellation | Cassiopeia |
| Object type | Supernova remnant |
| Right ascension | 00h 25m 21.5s |
| Declination | +64° 08′ 27 ″ |
| Peak apparent magnitude | -4 |
| Apparent size | 8′ |
| Distance | 8,000 – 9,800 light-years (2,500 – 3,000 parsecs) |
| Names and designations | Tycho’s Supernova, Tycho’s SN, Tycho SNR, Tycho’s Nova, Tycho’s Star, SN 1572, SN 1572A, Cepheus X-1, Cep X-1, B Cassiopeiae, B Cas, Nova Cassiopeiae 1572, Nova Cas 1572, 3C 10, SNR G120.1+01.4, SNR G120.2+01.4, 3A 0022+638, AJG 112, ASB 1, HR 92, BD+63 39a, BG 0022+63, BWE 0022+6351, 2C 34, 4C 63.01, 8C 0022+638, CGPSE 107, 3CR 10, CTA 2, CTB 4, NRAO 22, F3R 3628, DA 11, DB 2, 2E 83, 2E 0022.1+6353, 1ES 0022+63.8, HBH 1, GB6 B0022+6352, 87GB 002241.1+635151, GPA 120.11+1.41, GRS G120.10 +01.40, 1XRS 00224+638, 1H 0022+638, H 0021+63, KR 101, 1M 0022+639, MY 002240.5+640959.9, PBC J0024.9+6407, 1RXS J002509.2+640946, WN B0022.5+6351, WB 0022+6351, SRGA J002512.3+640822, SWIFT J0024.9+6407, SWIFT J0025.2+6410, TeV J0025+640, [KRL2007b] 2, [FS2003] 0015, [DGW65] 3, 2U 0022+63, 3U 0022+63, 4U 0022+63, VRO 63.00.01, VER J0025+641 |
Images
This Chandra image of the Tycho supernova remnant contains new evidence for what triggered the original supernova. Tycho was formed by a Type Ia supernova, a category of supernovae used in measuring astronomical distances because of their reliable brightness. In the lower left region of Tycho is a blue arc of X-ray emission. Several lines of evidence support the conclusion that this arc is due to a shock wave created when a white dwarf went out as a supernova and blew material off the surface of a nearby companion star. This supports one popular scenario for the trigger of a Type Ia supernova. Understanding the origin of Type Ia supernovae is important because they have been used to determine that the universe is expanding at an accelerating rate. Credit: NASA/CXC/Chinese Academy of Sciences/F. Lu et al. (PD)
This image from NASA’s Wide-field Infrared Survey Explorer (WISE) takes in several interesting objects in the constellation Cassiopeia, none of which are easily seen in visible light. The red circle visible in the upper left part of the image is SN 1572, often called “Tycho’s Supernova”. In the centre of the image is a star forming nebula of dust and gas, called S175 (in the Sharpless catalog of ionized nebula). This cloud of material is about 3,500 light years away and 35 light-years across. It is being heated by radiation from young hot stars within it, and the dust within the cloud radiates infrared light. On the left edge of the image, between the Tycho supernova remnant and the very bright star, is an open cluster of stars, King 1, first catalogued by Ivan King, an astronomer at UC Berkeley. This cluster is about 6,000 light-years away, 4 light-years across and is about 2 billion years old. Also of interest in the lower right of the image is a cluster of very red sources. Almost all of these sources have no counterparts in visible light images, and only some have been catalogued by previous infrared surveys. Image: NASA/JPL-Caltech/WISE Team (PD)
X-ray & Optical images of Tycho – A long Chandra observation of Tycho has revealed a pattern of X-ray “stripes” never seen before in a supernova remnant. The stripes are seen in the high-energy X-rays (blue) that also show the blast wave, a shell of exceptionally energetic electrons. Low-energy X-rays (red) show expanding debris from the supernova event. The stripes, seen to the lower right of this image, may provide the first direct evidence that a cosmic event can accelerate particles to energies a hundred times higher than achieved by the most powerful particle accelerator on Earth. Credit: NASA/CXC/Rutgers/K.Eriksen et al. (PD)
Gamma-rays detected by Fermi’s LAT show that the remnant of Tycho’s supernova shines in the highest-energy form of light. This portrait of the shattered star includes gamma rays (magenta), X-rays (yellow, green, and blue), infrared (red) and optical data. Image credit: Gamma ray, NASA/DOE/Fermi LAT Collaboration; X-ray, NASA/CXC/SAO; Infrared, NASA/JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS (CC BY 2.0)