C/2017 K2 (PanSTARRS) is an
Oort cloud comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...
with an inbound hyperbolic orbit, discovered in May 2017 at a distance beyond the orbit of
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
when it was from the Sun.
Precovery
In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...
images from 2013 were located by July.
It had been in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
of
Draco
Draco is the Latin word for serpent or dragon.
Draco or Drako may also refer to:
People
* Draco (lawgiver) (from Greek: Δράκων; 7th century BC), the first lawgiver of ancient Athens, Greece, from whom the term ''draconian'' is derived
* D ...
from July 2007 until August 2020. , the
3-sigma uncertainty in the current distance of the comet from the Sun is .
The comet is record breaking because it is already becoming active at such a distance. Only
Comet Hale–Bopp
Comet Hale–Bopp (formally designated C/1995 O1) is a comet that was one of the most widely observed of the 20th century and one of the brightest seen for many decades.
Alan Hale and Thomas Bopp discovered Comet Hale–Bopp separately ...
produced such a show from that distance with a similar nucleus. However, this comet will not be as visible as Hale–Bopp was in 1997 in part because it does not come nearly as close to the Sun. Astronomers had never seen an active inbound comet this far out, where sunlight is 1/225th its brightness as seen from Earth. Temperatures, correspondingly, are at -440 °F (-262 °C) in the Oort cloud. However, as it was approaching the Sun at a distance of 16 AU at discovery, a mix of ancient ices on the surface containing oxygen, nitrogen, carbon dioxide and carbon monoxide began to sublimate and shed the dust frozen into it. This material expands into a vast wide halo of dust, called a
coma
A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...
, enveloping the solid nucleus.
Research with the
Canada–France–Hawaii Telescope
The Canada–France–Hawaii Telescope (CFHT) is located near the summit of Mauna Kea mountain on Hawaii's Big Island at an altitude of 4,204 meters (13,793 feet), part of the Mauna Kea Observatory. Operational since 1979, the telescope is a Pri ...
(CFHT) infers the
comet nucleus to have a radius between , so there is a chance the nucleus could be as large as C/1995 O1 (
Hale-Bopp).
However, research with the
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
(HST) estimates the nucleus to have a circular equivalent diameter of less than .
On 17 September 2020, morphological studies of the inner coma, observed on 12 September 2020, were reported, noting that two jet-streamed structure were emitted from the nucleus and, as well, that the length of the tail was about long.
The comet was within of Earth by 11 January 2022.
Around 6 July 2022, the comet crossed the
celestial equator, and then on 14 July 2022, it passed from Earth
and shone around 9.0 magnitude making it a decent
binoculars
Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...
object.
It reached
perihelion on 19 December 2022, close to the orbit of
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
, and was not be visible to naked eye at 8.0 magnitude.
On 27 July 2021, further detailed observations of the comet were reported on ''
The Astronomer's Telegram
''The Astronomer's Telegram'' (''ATel'') is an internet-based short-notice publication service for quickly disseminating information on new astronomical observations. Examples include gamma-ray bursts, gravitational microlensing, supernovae, nova ...
''.
models that C/2017 K2 took millions of years to come from the Oort cloud at a distance of roughly .
The heliocentric
orbital eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values betwee ...
drops below 1 in December 2023.
The outbound orbital period will be around years.
Gallery
File:Distant active comet C 2017 K2.jpg, June 2017 by Hubble's Wide Field Camera 3Messier 10
Messier 10 or M10 (also designated NGC 6254) is a globular cluster of stars in the celestial equator, equatorial constellation of Ophiuchus. The object was discovered by the French astronomer Charles Messier on May 29, 1764, who cataloged it as n ...
File:C2017_K2_skypath.png, Path of C/2017 K2 in the sky
References
Notes
External links
C/2017 K2 (PANSTARRS) Taken by ALBERTO QUIJANO VODNIZA on August 9, 2022 @ PASTO,NARINO. COLOMBIAA Comet Active Beyond the Crystallization Zone*
ttps://arxiv.org/abs/1802.10380 Note on the dynamical evolution of C/2017 K2 PANSTARRS(arXiv 2018)
C/2017 K2 EarthSky July 12 2022
C/2017 K2 (PANSTARRS) motion as seen by Catalina Sky Survey22 August 2020
{{DEFAULTSORT:C 2017 K2
Cometary object articles
Non-periodic comets
20170521
Comets in 2022
Oort cloud
Discoveries by Pan-STARRS