This artist's rendering shows the asteroid (above), and Mercury (below). Credit: CTIO/NOIRLab/NSF/AURA/J. da Silva
Astronomers discovered an asteroid that orbited the Sun in a ten-day period using the powerful Dark Energy Camera (DECam), Chile's powerful 570-megapixel Dark Energy Camera. The orbit of this asteroid, which measures approximately 1 km in diameter, takes it close to the Sun at 20 million kilometers (12,000,000 miles or 0.13AU) every 113 days. Images taken during twilight revealed that Asteroid 2021PH 27 also has the lowest mean distance (semimajor) of all known asteroids in our Solar System. Only Mercury has a shorter period, and a smaller semi-major. Because it is so close to Sun's massive gravitational fields, the asteroid experiences the greatest general relativistic effects of all Solar System objects.
Scott S. Sheppard of Carnegie Institution of Science discovered the asteroid 2021PH 27 in data from the Dark Energy Camera (DECam), mounted on Cerro Tololo Inter-American Observatory in Chile. Ian Dell'antonio of Brown University took the discovery images of the Asteroid in the twilight sky on the night of 13 August 2021. Sheppard had teamed with Dell'antonio, Fu and other observers while they were conducting observations with DECam in order to study most of the large galaxy clusters within the local Universe. They took time out from observing some of the largest objects millions of light-years away to search for far smaller objectsasteroidscloser to home.
DECam is one of the most powerful, wide-field CCD imagingrs on the planet. It was created for the DOE's Dark Energy Survey (DES). The DOE funded the construction and testing at Fermilab. Between 2013 and 2019, the DOE and NSF operated DECam. DECam is currently used for a wide range of science programs. Community Science and Data Center (CSDC) curates the DECam science archives. CSDC and CTIO are both programs of NSF's NOIRLab.
The best time to search for asteroids interior to Earth's orbit is at sunset or before sunrise. This is in the direction Mercury and Venus. Stargazers will tell you that Mercury and Venus are never visible far from the Sun and are best seen near sunset or sunrise. Asteroids, which orbit near the Sun, are also subject to the same rules.
David Tholen, University of Hawai'i, measured the asteroid's location and predicted where it would be observed the next evening. It was then observed again by DECam and the Magellan Telescopes of the Las Campanas Observatory, Chile, on the 14th August 2021. Marco Micheli, European Space Agency, used the Las Cumbres Observatory network (1- to 2-meter telescopes) to observe it from CTIO, Chile, and South Africa. Astronomers had postponed their original observations in order to see the newly discovered asteroid.
NOIRLabs CTIO has discovered the fastest orbital period asteroid within the Solar System. It was found using the powerful Dark Energy Camera (DECam), a powerful 570-megapixel Dark Energy Camera in Chile, the Sun's new closest neighbor. The asteroid was photographed inside Mercury's orbit. It has been colored blue and red to indicate the time it was taken on the discovery night 13 August 2021, just three minutes apart. Credit: CTIO/NOIRLab/NSF/DOE/DECam/AURA/S.S. Sheppard (Carnegie Institution of Science).
Sheppard says that even though telescope time is precious for astronomers, the international nature of astronomers and love for the unknown make them willing to sacrifice their science and observations in order to pursue new, exciting discoveries like this.
Asteroids and planets orbit the Sun in elliptical orbits. The semi-major orbit is the radius of the largest axis. 2021 PH 27, which has a semimajor axis at 70 million kilometers (43,000,000 miles or 0.46au), gives it a 113-day orbital time on an elongated orbit, that crosses the orbits for both Mercury and Venus.
It could have started life in the main Asteroid Belt, between Mars and Jupiter, and was then dislodged from gravitational disturbances from inner planets that brought it closer to the Sun. However, its high orbital tilt of 32 degrees suggests that it could be an extinct comet that was captured by a terrestrial planet and placed in a shorter-period orbit. Future observations of this asteroid will provide more information about its origins.
Its orbit is likely to be unstable for long periods of time. In a few millions years it will collide with Mercury and Venus, or be ejected by the gravitational force of the inner planets.
These interior asteroids are often obscured by the Sun's glare, making it difficult for astronomers to find them. Asteroids that are so close to the Sun experience various stresses. These stresses include thermal stress from the Sun's heat and gravitational tidal force stresses. Some of these stresses may cause the destruction of some more fragile asteroids.
NOIRLabs CTIO has discovered the fastest orbital period asteroid within the Solar System. This was done using the powerful Dark Energy Camera (DECam), which is located in Chile, the Sun's nearest neighbor. This illustration shows the positions of the asteroid and planets on the night of 13 Aug 2021. It was taken from the Solar System's vantage point. It is possible that the asteroid may be an extinct comet, which was captured in a brief orbit near one of the terrestrial planets. The asteroid's 32 degree tilt suggests this. Future observations will provide more information about its origins. Credit: CTIO/NOIRLab/NSF/AURA/J. da Silva (Spaceengine).
Sheppard says that the fraction of asteroids located inside Earth and Venus will provide insight into their strength and makeup. If there is a decrease in the number of asteroids orbiting similar orbits to 2021 PH 27, it will tell astronomers how many near-Earth asteroids have piles of rubble, rather than solid chunks, which could have implications for asteroids that may be on a collision course to Earth and how they might be deflected.
Sheppard says, "Understanding Earth's asteroids is essential to complete the census. This includes the most likely Earth-impactors that could approach Earth during daylight." He also stated that "...'s surface temperature reaches almost 500°C (around 900° F) when it approaches the Sun in 2021 PH 27, which is close enough to melt lead.
2021 PH 27, which is so close to Sun's huge gravitational field and has the greatest general relativistic effects of all Solar System objects, experiences the most powerful general relativistic effects. Precession is a movement that causes a slight deviation in the orbit of an asteroid over time. It amounts to approximately one arcminute per year.
When it appears to be moving behind the Sun, the asteroid enters solar conjunction. It will likely return to Earth visibility in 2022 when new observations can be made to better determine its orbit. This will allow the asteroid to receive an official name.
Continue reading Astronomers discovered a 2-km-long asteroid orbiting nearer to the sun than Venus.
More information: Research report: Research report: www.minorplanetcenter.net/mpec/K21/K21Q41.html
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