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C/2019 Y4 (ATLAS)

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C/2019 Y4
File:Comet C-2019 Y4 ATLAS.jpeg
C/2019 Y4 as imaged from Makioka, Yamanashi, Japan, on February 17
Discovery
Discovered byAsteroid Terrestrial-impact Last Alert System (ATLAS)
Discovery date2019-12-28
Orbital characteristics
Epoch2458897.5
(2020-02-18)
Number of
observations		949
Aphelion662.0228763 AU
Perihelion0.2528486 AU
Semi-major axis331.1378624 AU
Eccentricity0.9992364
Orbital period6026 a
Inclination45.38°
Longitude of
perihelion		117.98°
Last perihelion4th Millenium BC

[[Current observed magnitude=7.6
Current Estimated magnitude=14.38
Coma Diameter=27'or 20 arcminutes
Distance from Earth=1.080 AU
Distance from Sun=1.5 AU

Family/Group= Nearly isotropic
]]
Next perihelion2020-05-31, 00:21:35 UT
TJupiter-0.454
Earth MOID0.063 AU
Jupiter MOID1.397 AU

C/2019 Y4 (ATLAS) is a near-parabolic comet that was discovered by the ATLAS survey on December 28, 2019, in Hawaii, which made it the last comet discovery of that year.[1]

It is currently the second-brightest comet of the night sky and is close to the limit of naked eye visibility from very dark locations. It brightens at a rate of 0.25 magnitudes per day and it is expected that the comet's apparent magnitude may peak between a magnitude of 2 (like Polaris) to –11 at perihelion, which is comparable to the brightness of Comet Ikeya–Seki. It is predicted that Comet ATLAS may reach magnitude –8.2 on its perigee and –11.7 on its perihelion. Another source said that it will reach 5 magnitude at 1 May, and peak a brightness between 2 and -6.

The coma (ATLAS's gaseous envelope) has ballooned in diameter and it is estimated to extend up to 720000 km, more than 5.5 times the diameter of Jupiter or about half as wide as the Sun or about 400 times bigger than Earth, by new images taken by an amateur astronomer who measuring the comet's angular diameter on 18 March 2020 when it was only 1.1 AU away from Earth. On the scale of big things in the Solar system Comet ATLAS falls between the Sun (1,392,000 km) and Jupiter (139,820 km). For observers on Earth they can see a 20 arcminutes or a half of degree wide coma (the thin dissipating dust ball around the comet's solid core or nucleus) as of 24 March, (for comparison the moon is 30 arcminutes wide as seen from Earth) and rapidly brightening day by day. It's not unusual for a comet to grow this large, while their solid ice cores are typically mere kilometers in diameter like Comet ATLAS, they can spew prodigious amounts of gas and dust into space, filling enormous volumes with their gossamer exhaust as they near the Sun. In the fall of 2007, Comet 17/P Holmes partially exploded, and for a while had an atmosphere even larger than the Sun. The Great Comet of 1811 also had a sun-sized coma. Whether comet ATLAS will eventually rival those behemoths of the past remains to be seen.we all remember the infamous Comet ISON in 2013, which was expected to deliver a spectacular show in the sky, but it then disintegrated as it passed around the sun, ending all hope of spectacle and back in 2000, C/1999 S4 LINNER dropped the same amount as it approached and dissolved rapidly,so it's not sure now that ATLAS will grace our skies and perform one of the biggest light show that we've seen in a while.

Discovery

C/2019 Y4 was discovered on CCD images taken on December 28, 2019, with a 0.5-m (1.6 ft) reflecting telescope atop Mauna Loa in Hawaii.[2] The images were taken as part of the Asteroid Terrestrial-impact Last Alert System (ATLAS). At the time of its discovery, the comet was in the constellation Ursa Major as viewed from Earth. Larry Dennau was the first to identify the object's cometary appearance,[3] placing the object on the Minor Planet Center's Possible Comet Confirmation Page, alerting other astrometrists. Further observations over subsequent days identified a coma; a comet tail became increasingly apparent as observations continued.[2]

Physical properties and tail

File:Screenshot 2020-03-22-16-28-45-913 com.miui.gallery.jpg
Comet ATLAS looked like a misty ball of light with a bright core (or nucleus) on March 11. Hints of a tail a tail are visible in both photos. Captured by Michael Jager (main) and Gianluca Masi.

Like all comets, ATLAS produces a green tail as the carbon and cyanide gas within the comet is ionised as it approaches the sun. Some amateur astronomers have observed that it has a 30' or 0.12° thin dust tail. Right now comet ATLAS is the biggest green object in the Solar system. Its verdant hue comes from diatomic carbon, C2, a common molecule in comets. Gaseous C2 emits a green colour that could become visible to naked eye in mid-April as comet ATLAS moves closer to Earth and Sun.[4]

Location

Comet's trajectory in the sky with 7-day markers

During January to March 2020, the comet is located in the constellation Ursa Major. In April when skies become dark it will be visible halfway up in the north-northwest sky in the evening in the constellations of Perseus and Camelopardalis and in June it will be visible in Orion in the north-northeast sky at morning and potentially visible with the naked eye.[5]

Orbit

File:Screenshot 2020-03-22-16-56-03-803 com.miui.gallery.jpg
Orbit of Comet ATLAS is tilted 45° with respect to the plane of the planets

The first orbital calculations for C/2019 Y4 were published on the Minor Planet Electronic Circular based on observations taken between December 28, 2019, and January 9, 2020, indicating a 4,400-year orbital period and a perihelion of 0.252946 AU. Similarities were noted between the orbital elements of C/2019 Y4 and the Great Comet of 1844 (C/1844 Y1), though the intrinsic brightness of the newly-discovered comet was dimmer.[2] Based on data hosted on the JPL Small-Body Database with an epoch of February 18, 2020, C/2019 Y4 has an orbital period of approximately 6,026 years, and is expected to reach perihelion on May 31, 2020.[6]

It has been identified as a hyperbolic comet, meaning its orbit stretches deeper into the Cosmos, with the Sun only acting as a gravitational slingshot to hurtle it further out of the solar system.[citation needed]

The comet has a similar orbit to the Great Comet of 1844, leading to speculation on whether C/2019 Y4 is a fragment of the same parent body as the 1844 Comet. The nucleus has already been baked by the sun at its previous encounter some 5000 years ago when presumably a much larger comet broke into at least 2 pieces, that later returned as great comet C/1844 Y1—also known as Wilmot's Comet—and Comet C/2019 Y4.

File:Screenshot 2020-03-22-16-56-10-232 com.miui.gallery.jpg
Comet ATLAS in upper left and mighty Galaxies M81 and M82 (Bode's Nebulaes) on lower right

Comet ATLAS will be in its perigee on May 23, 2020 at a distance of 72,610,769 miles or 116,855,706 km from Earth, and will reach perihelion on May 31, 2020 at a distance from 23,517,819 miles or 37,848,261 km.

It is currently in close proximity to Mars' orbit and approaching the Sun. At present, while in the vicinity of our neighbouring planet, ATLAS shines as bright as an eighth-magnitude fuzzy star and can be observed through mid-sized telescopes.

Observation

File:Screenshot 2020.jpg
light curve showing the brightness of comet ATLAS and dots represent observed magnitude
File:Screenshot 2020-03-22-16-28-35-391 com.miui.gallery.jpg
light curve predicting minor,modarate and major brightness of comet ATLAS and dots represent observed magnitude.[7]

Astronomers are continuing to observe this comet.[8]

Stripped of volatiles, it has only become active at 2.1 AU when crossing the ice line beyond the orbit of Mars.

Karl Battams of the Naval Research Lab in Washington DC said:

"Comet ATLAS continues to be much brighter than expected. Some predictions for its peak brightness now border on the absurd. If it has a big nucleus with large stones of frozen gas, then yes; We could get a very bright Comet. Right now the Comet is releasing huge amounts of its frozen volatiles or gases. That's why it is brightening so fast, otherwise comet ATLAS might run out of gas, crumbling and fading as it approaches the Sun. current best estimates of the comet peak brightness in May range from magnitude +1 to -5. If the comet hits the high end of that range, a bit brighter than Venus. Comet McNaught or C/2006 P1 performed that very trick 13 years ago. On January 13, 2007, it swooped past the sun shining at a brilliant magnitude of -5.5. The absurdly-bright comet was visible at high on noon with its tail jutting across the blue sky.[9]

Battams is not optimistic, though, he added;

My personal intuition is that comet ATLAS is over achieving, and I wouldn't be surprised to see it fade rapidly and possibly even disintegrate before reaching the Sun. ATLAS is a bit of a wildcard, and there's a spectrum of possibilities as it nears the sun. At one extreme, it could simply crumble away in the coming weeks and at another extreme it could brighten up tremendously. It has an unusually small perihelion distance inside of Mercury's orbit, which bodes well for getting those frozen gasses fizzing furiously. If it can survive the blast furnace of the solar heating, it could put on a good show. However, no one expected the show to start more than two months before its perihelion. Comet ATLAS is already heating up. Outbursts are possible in the upcoming weeks as new veins of volatile material are exposed by intensifying sunlight. The worldwide Comet Observation Database shows it jumping from magnitude +17 in early February to +8 in mid-March,4000 times brighter since its discovery. It could become visible to the naked eye in early April at this rate. If it doesn't fly apart first, it could become one of the brightest comets in years. However, the fate of the comet is still unclear. We do not know if it will ever return to our astronomical neighborhood again. He added, we have a number of space telescopes designed to view objects very close to sun. The Heliospheric Image on NASA's STEREO spacecraft will get a great view of it from mid-May through early June 2020. So, we might be able to observe ATLAS's tail interacting with the Solar wind and outflows as well as any potentially breakup events. There's also WISPR camera on NASA's Parker Solar Probe. We will potentially be able to view ATLAS from WISPR camera concurrently with the STEREO observations. But it would require a non-standard pointing configuration for us, so the operation teams are currently assessing our options. So it's going to be fun the next few weeks watching comet ATLAS devolop.

John Bortle,who has observed hundred of comets and is a well known expert in the field, got his first look of comet ATLAS through his 15×70 binocular on the night of Sunday, March 15, and he's stumped. He said that,

For the first time in many years I am left at a bit of loss as to what honestly worthy advice I can offer would be observers. I really don't know quite what to make of this object. The head (or coma) of comet ATLAS is big, very faint and ghostly, which doesn't make sense. If it's a truly significant visitor, it should be considerably sharper in appearance. Instead we see at best, a quite modestly condensed object with only a pinpoint stellar feature near its heart.[10]

Jonathan Shanklin, Director of the British Astronomical Association's BAA comet section, reported that,

The current comet, C/2019 Y4, brightened quite rapidly in mid-February and as of 11 March there is no sign of a slowdown in the rate of brightening. It is already visible in large binoculars. The uncertainty in brightness at the time of perihelion is large, through the worst case indicated is 2nd magnitude, it will remain well placed for UK observation into May and could become a prominent object.[11]

Another amateur astronomer Micheal Jaeger reported to BAA that,

C/2019 Y4 brightening quite rapidly in mid-February. Talking the recent observation at face value would indicate that it might reach a brightness near of the sun at perihelion.[12]

Carl Hergenrother, an assiduous comet observer based in Arizona, said,

We should expect the rate of increase to slow down. Until a couple of weeks ago,it was brightening at an astounding rate. The brightening has slowed somewhat,but it is still an impossible rate of brightening to maintain. This is where it gets tricky to predict just how bright it will get. Were ATLAS to continue to brighten with this rate all the way to its closest approach to the sun at the end of May,it would end up rivalling the planet Venus in brightness. Right now, no one can predict how long it will continue to quickly brighten and how dramatically that brightening will slow.[13]

Three weeks ago amateur astronomer Roman Kulesza of Ontario, Canada tried to find comet ATLAS but to no avail. He said,

It wasn't easy but last several nights-wow! The comet has really brightened.

The comet has also been found to be a hundred times bigger and brighter than what astronomers were originally estimating. Since its discovery when it was at a magnitude of 20, it has brightened nearly 398,000 times. When it was discovered beyond the orbit of Mars,273 Miles away from us, it is estimated that the comet will be 9th magnitude star on its perihelion and can be visible on telescope, but things changed when astronomer realised the rate of brightness of increase. Almost day-by-day rapid changes have been observed and now at a stage where the comet is 600 times more brighter than predicted at this point. At such rate it could be visible to people in zones free from light pollution with their naked eye in just couple of weeks as the comet will perform a good show for couple of months. It's because as a comet move closer to Sun it burn more intensely and release more frozen volatiles, However it will be best viewed in the Northern Hemisphere unlike the Great Comet of 1843 or comet Wilmot. By the time Comet ATLAS approaches the sun in late May it could become quite bright indeed. At present while in the vicinity of our neighbouring planet, ATLAS shines as an eighth magnitude fuzzy star, which is barely visible to the naked eye from any remote location, but can be observable through mid-sized backyard telescopes. Barely visible some three weeks ago, it has now surged in brightness and will continue to do so as it approaches the centre of our solar system. The comet has also been found to be hundreds of times bigger and brighter than what astronomers had originally estimated, possibly signalling an explosion or outburst of dust and gas in the comet's core or nucleus.If that continues to occur on its way to perihelion or if it brightens at a rate of 0.50 magnitude per day, which is double the current rate, then the comet may become the brightest comet in human history and be visible during daylight, which is very commonly seen for Kreutz sungrazer comet. However the comet is rather small with an absolute magnitude of 2-3 mag which is below the Bortle Unit. Thus it is very likely that the comet will disintegrate well before reaching perihelion.

References

  1. ^ Dickinson, David (February 25, 2020). "Comet Y4 Atlas in Outburst: First Good Comet for 2020?". Universe Today. Retrieved February 29, 2020.
  2. ^ a b c Green, Daniel W. E. (January 11, 2020). "COMET C/2019 Y4 (ATLAS)". Liste de distribution des circulaires de l'Union Astronomique Internationale et du Minor Planet Center (Mailing list). Retrieved March 25, 2020.
  3. ^ "MPEC 2020-A112 : COMET C/2019 Y4 (ATLAS)". minorplanetcenter.net. Minor Planet Electronic Circular. Cambridge, Massachusetts: Minor Planet Center. January 10, 2020. Retrieved March 24, 2020.
  4. ^ Ghosh, Trinankur (March 21, 2020). "Comet ATLAS'S tail". Retrieved March 22, 2020.
  5. ^ Ghosh, Trinankur (March 16, 2020). "Comet ATLAS is brightening". Space. Retrieved March 21, 2020.
  6. ^ "C/2019 Y4 (ATLAS)". JPL Small-Body Database Browser. Jet Propulsion Laboratory. Retrieved March 24, 2020.
  7. ^ "C/2019 Y4 (ATLAS)". astro.vanbuitenen.nl. Retrieved March 20, 2020.
  8. ^ Ghosh, Trinankur (March 19, 2020). "Comet ATLAS to shine as bright as crescent moon in May 2020". The Weather Channel. Retrieved March 20, 2020.
  9. ^ Phillips, Tony (March 16, 2020). "Comet ATLAS is Brightening Faster than Expected". Spaceweather. Retrieved March 20, 2020.{{cite web}}: CS1 maint: url-status (link)
  10. ^ Rao, Joe (March 21, 2020). "Newfound Comet ATLAS is getting really bright, really fast". Space.com. Retrieved March 20, 2020.{{cite web}}: CS1 maint: url-status (link)
  11. ^ Ghosh, Trinankur (March 20, 2020). "Comet ATLAS". Retrieved March 21, 2020.
  12. ^ Ghosh, Trinankur (March 20, 2020). "Comet ATLAS". Retrieved March 21, 2020.
  13. ^ Rao, Joe (March 20, 2020). "Newfound Comet ATLAS is getting really bright, really fast". Space.com. Retrieved March 21, 2020.{{cite web}}: CS1 maint: url-status (link)



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