C/2019 Y4 (ATLAS)

{{For|other comets discovered by the Asteroid Terrestrial-impact Last Alert System|Comet ATLAS (disambiguation)}}

{{Infobox comet

| name = C/2019 Y4 (ATLAS)

| image = 2019Y4-20200314.jpg

| caption = C/2019 Y4 (ATLAS) imaged on March 14, 2020

| discoverer = ATLAS–MLO

| mpc_name = {{unbulleted|C/2019 Y4-A|C/2019 Y4-B|C/2019 Y4-C|C/2019 Y4-D|C/2019 Y4-E}}

| designations = A10j7UG

| discovery_date = December 28, 2019

| orbit_ref = {{cite web | url=https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1003655 | title=Small-Body Database Lookup }}

| epoch = March 7, 2020
(JD 2458915.5)

| observation_arc = 115 days

| obs = 1250

| aphelion = {{val|660.9626|3.2491}} AU

| perihelion = 0.2528 AU

| semimajor = {{val|330.6077|1.6252}} AU

| eccentricity = 0.99924

| period = {{val|6,011.43|44.33}} yr

| inclination = 45.3839°

| asc_node = 120.5721°

| arg_peri = 177.4084°

| tjup = 0.454

| Earth_moid = {{cvt|0.631177|AU|km|abbr=on}}

| Jupiter_moid = 1.39373 AU

| physical_ref = {{r|JPL SBDB|Jewitt_2022}}

| dimensions = {{cvt|0.4|–|1.0|km|mi}}

| mean_diameter = {{cvt|0.6|km|mi}}

| M1 = {{val|9.9|0.9}}

| M2 = {{val|13.1|0.7}}

| magnitude = 7.0
{{small|(2021 apparition)}}

| last_p = 31 May 2020

}}

C/2019 Y4 (ATLAS) was a comet with a near-parabolic orbit discovered by the ATLAS survey on December 28, 2019.{{cite web |last1=Dickinson |first1=David |title=Comet Y4 Atlas in Outburst: First Good Comet for 2020? |url=https://www.universetoday.com/145036/comet-y4-atlas-in-outburst-first-good-comet-for-2020/ |website=Universe Today |access-date=February 29, 2020 |date=February 25, 2020}} Early predictions based on the brightening rate suggested that the comet could become as bright as magnitude 0 matching the brightness of Vega. It received widespread media coverage due to its dramatic increase in brightness and orbit similar to the Great Comet of 1844, but on 22 March 2020, the comet started disintegrating. Such fragmentation events are very common for Kreutz Sungrazers. The comet continues to fade and did not reach naked eye visibility. By mid-May, comet ATLAS appeared very diffuse even in a telescope. C/2019 Y4 (ATLAS) has not been seen since 21 May 2020.

C/2019 Y4 (ATLAS) was the brightest on March 30 when it had an apparent magnitude of about 7, but after disintegrating, it continued to fade, until it was last observed on May 21. It is located in the constellation Monoceros but is no longer visible. It reached its nearest point to Earth on May 23 and come to perihelion (closest to the Sun) on May 31.

In April 2020, astronomers reported, on The Astronomer's Telegram, the possible disintegration of Comet ATLAS.{{cite news |last1=Steele |first1=I.A. |last2=Smith |first2=R.J. |last3=Marchantn |first3=J. |title=ATel #13622: C/2019 Y4 ATLAS – confirmation of nuclear change |url=http://www.astronomerstelegram.org/?read=13622 |date=April 6, 2020 |work=The Astronomer's Telegram |access-date=April 7, 2020 }}{{cite news |author=Lin, Zhang-Yi |display-authors=et al. |title=ATel #13629: The fragmentation of comet C/2019 Y4 (Atlas) observed at Lulin observatory |url=http://www.astronomerstelegram.org/?read=13629 |date=April 13, 2020 |work=The Astronomer's Telegram |access-date=April 13, 2020}} The comet has fragmented into at least 4 pieces.[https://www.astrobin.com/uzoxkq/B/ Philipp Keller (Astrooptik) RC 900mm F/10]{{cite news |last1=Ye |first1=Quanzhi |last2=Hui |first2=Man-To |title=ATel #13651: Continuing Fragmentation of C/2019 Y4 (ATLAS) |url=http://www.astronomerstelegram.org/?read=13651 |date=April 21, 2020 |work=The Astronomer's Telegram |access-date=April 22, 2020 }} NASA subsequently reported that the Hubble Space Telescope has identified that there could be as many as roughly "30 fragments on April 20, and 25 pieces on April 23."

{{cite web

|url=https://www.nasa.gov/feature/goddard/2020/hubble-watches-comet-atlas-disintegrate-into-more-than-two-dozen-pieces

|title=Hubble Watches Comet ATLAS Disintegrate Into More Than Two Dozen Pieces

|last1=Andreoli

|first1=Claire

|last2=Villard

|first2=Ray

|last3=Jewitt

|first3=David

|last4=Ye

|first4=Quanzhi

|date=April 28, 2020

|website=www.nasa.gov

|publisher=National Aeronautics and Space Administration

|access-date=April 28, 2020}}

The fragmentation may be the result of outgassing causing an increase in the centrifugal force of the comet.

The Solar Orbiter flew through the ion tail of comet ATLAS between May 31 and June 1 and the dust tail on June 6.

Discovery

Comet ATLAS was discovered on CCD images taken on December 28, 2019, with a {{convert|0.5|m|in|abbr=on}} reflecting telescope atop Mauna Loa in Hawaii. The images were taken as part of the Asteroid Terrestrial-impact Last Alert System (ATLAS). At the time of its discovery, the comet shone at magnitude 19.6 in the constellation Ursa Major as viewed from Earth.{{cite web |last1=Ling |first1=Alister |title=Comet ATLAS may soon be visible to the naked eye |url=https://astronomy.com/news/observing/2020/03/comet-atlas-may-soon-be-visible-to-the-naked-eye |website=Astronomy |publisher=Kalmbach Media |access-date=March 27, 2020 |date=March 25, 2020}} Larry Denneau was the first to identify the object's cometary appearance,{{cite web |title=MPEC 2020-A112 : COMET C/2019 Y4 (ATLAS) |url=https://minorplanetcenter.net/mpec/K20/K20AB2.html |website=minorplanetcenter.net |publisher=Minor Planet Center |access-date=March 24, 2020 |location=Cambridge, Massachusetts |date=January 10, 2020|series=Minor Planet Electronic Circular}} placing the object on the Minor Planet Center's Possible Comet Confirmation Page, alerting other astronomers. Further observations over subsequent days identified a coma; a comet tail became increasingly apparent as observations continued.{{cite mailing list|url=http://mail.spaceobs.com/pipermail/iaude_spaceobs.com/2020-January/018673.html|title=COMET C/2019 Y4 (ATLAS)|date=January 11, 2020|access-date=March 25, 2020|mailing-list=Liste de distribution des circulaires de l'Union Astronomique Internationale et du Minor Planet Center|last=Green|first=Daniel W. E.|archive-date=March 25, 2020|archive-url=https://web.archive.org/web/20200325215812/http://mail.spaceobs.com/pipermail/iaude_spaceobs.com/2020-January/018673.html|url-status=dead}}

Initial observation and brightness

File:Comet Atlas with reduced Coma .jpg

Between the beginning of February and near the end of March, Comet ATLAS brightened from magnitude 17 to magnitude 8, representing a 4000-fold increase in brightness.{{cite web |last1=Yirka |first1=Bob |title=Comet ATLAS may put on quite a show |url=https://phys.org/news/2020-03-comet-atlas.html |website=Phys.org |publisher=Science X Network |access-date=March 27, 2020 |date=March 23, 2020}} In March 2020, the comet's brightness increased four magnitudes. C/2019 Y4's green or aqua colour arose from emissions of diatomic carbon with a 1.2° or 10' or {{val|3.3|u=million km}} multicolour tail, more than twice as wide as the Sun. As a diffuse object, the comet would need to reach an apparent magnitude of around 3{{ndash}}4 to be obvious to the casual observer in a dark sky. A 4th magnitude comet in bright twilight is not very impressive nor obvious. In early April, the comet faded due to a significant fragmentation event.{{Cite web |url=http://cara.uai.it/comet-c2019-y4-atlas-after-unexpected-bit-irregular-rising-brightness-comet-now-fading |title=Comet C/2019 Y4 (ATLAS): after an unexpected, a bit irregular, rising in brightness the comet is now fading |access-date=April 4, 2020 |archive-url=https://web.archive.org/web/20200408043357/http://cara.uai.it/comet-c2019-y4-atlas-after-unexpected-bit-irregular-rising-brightness-comet-now-fading |archive-date=April 8, 2020 |url-status=dead }} On April 14, 2020, initial estimates of water production by the comet were reported, and found "a water production rate of 1.25×10²⁸ +/− 5×10²⁵ mol/sec within an aperture of 100,000 km".{{cite news |author=Venkataramani, Kumar |display-authors=et al. |title=ATel #13634: First Estimate of Water Production Rates of Comet C/2019 Y4 (ATLAS) from SWIFT/UVOT observations |url=http://www.astronomerstelegram.org/?read=13634 |date=April 14, 2020 |work=The Astronomer's Telegram |access-date=April 14, 2020 }}

Orbit

File:Hubble Watches Comet ATLAS Disintegrate Into More Than Two Dozen Pieces (49832598833).png in late April 2020]]

At the time of its discovery Comet ATLAS was nearly 3 astronomical units (AU) from the Sun. The first orbital calculations for the comet were published on the Minor Planet Electronic Circular, and were based on observations taken between December 28, 2019, and January 9, 2020, which indicating a 4,400-year orbital period and a perihelion of 0.25 AU. Similarities were noted between the orbital elements of C/2019 Y4 and the Great Comet of 1844 (C/1844 Y1), suggesting that C/2019 Y4 is a fragment of the same parent body, split about five thousands years ago.{{cite web |last=Andreoli |first=Claire |url=https://www.nasa.gov/feature/goddard/2021/comet-atlas-may-have-been-a-blast-from-the-past |title=Comet Atlas May Have Been a Blast From the Past |publisher=NASA |date=August 19, 2021 |access-date=August 19, 2021}}{{cite journal|arxiv=2004.10990|last1=Hui|first1=Man-To|last2=Ye|first2=Quan-Zhi|title=Observations of Disintegrating Long-period Comet C/2019 Y4 (ATLAS): A Sibling of C/1844 Y1 (Great Comet)|journal=The Astronomical Journal|year=2020|volume=160|issue=2|page=91|doi=10.3847/1538-3881/ab9d81|bibcode=2020AJ....160...91H|s2cid=216080893 |doi-access=free }}{{cite web |last1=King |first1=Bob |title=Comet ATLAS: Will it Become a Naked-Eye Object? |url=https://skyandtelescope.org/astronomy-news/comet-atlas-will-it-become-a-naked-eye-object/ |website=Sky & Telescope |publisher=AAS Sky Publishing, LLC |access-date=March 27, 2020 |date=March 25, 2020}}

The JPL Small-Body Database using an epoch of February 18, 2020, shows C/2019 Y4 (ATLAS) with an orbital period of approximately 6,000 years, but this solution includes misleading perturbations while inside of the planetary region. A more useful barycentric solution before the comet entered the planetary region shows an inbound orbital period of about 4,800 years. The comet reached its nearest point to the Sun on May 31, 2020.{{cite web |title=C/2019 Y4 (ATLAS) |url=https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019Y4 |website=JPL Small-Body Database Browser |publisher=Jet Propulsion Laboratory |access-date=March 24, 2020}} After leaving the planetary region, the comet will have an outbound orbital period of about 5,200 years.

The fragmentation of C/2019 Y4 in late March 2020, has changed the velocities of the fragments by up to 10 meters/second (25000 km/month). This small change in velocity can cause a big change in the long-term orbital period of these near-parabolic fragments. The short observation arc of ~10 days for fragments D&E results in large uncertainties in the orbital periods. Fragment B was observed the longest. Fragment D may have come the closest to Earth but due to the short observation arc has an uncertainty of ±2 million km in the close approach distance.[https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2019Y4-D JPL Horizons Fragment D] Table Setting "39. Range" for 2020-May-23 06:44

class="wikitable sortable" style="font-size: 0.9em;" \|+Orbital period of fragments ! Fragment ! Orbital period (years) ! Closest Approach to Earth ! obs arc (days)
C/2019 Y4-A	ejection[https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019Y4-A JPL SBDB: C/2019 Y4-A]	{{Convert\|0.7858\|AU\|e6km\|abbr=unit\|lk=on}}	27
C/2019 Y4-B	{{val\|17200\|2300}}[https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019Y4-B JPL SBDB: C/2019 Y4-B]	{{Convert\|0.7816\|AU\|e6km\|abbr=unit\|lk=off}}	40
C/2019 Y4-C	ejection[https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019Y4-C JPL SBDB: C/2019 Y4-C]	{{Convert\|0.7824\|AU\|e6km\|abbr=unit\|lk=off}}	26
C/2019 Y4-D	{{val\|126\|86}}[https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019Y4-D JPL SBDB: C/2019 Y4-D]	{{Convert\|0.7777\|AU\|e6km\|abbr=unit\|lk=off}}	8
C/2019 Y4-E	{{val\|88\|32}}[https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019Y4-E JPL SBDB: C/2019 Y4-E]	{{Convert\|0.7794\|AU\|e6km\|abbr=unit\|lk=off}}	6

Location

During January to March 2020, the comet was located in the constellation of Ursa Major. Throughout the month of April, the comet was in the constellation of Camelopardalis. On May 12 it moved into Perseus. It was {{Convert|0.78|AU|e6km LD|abbr=unit|lk=on}} from Earth on May 23 during a new moon when the comet was 17 degrees from the Sun. At its perihelion on May 31, it was in the Taurus constellation 12 degrees from the Sun.{{cite web

|last1=Rao |first1=Joe

|title=Newfound Comet ATLAS is getting really bright, really fast

|url=https://www.space.com/comet-atlas-may-be-brightenting.html

|website=Space.com

|access-date= March 21, 2020

|date= March 16, 2020}} Then, through June and July, it passed through Orion and Monoceros.

{{multiple image

| header = C/2019 Y4 (ATLAS)

| direction = horizontal

| align = left

| image1 = Comet 2019 Y4 ATLAS-sky.png

| caption1 = Comet ATLAS's trajectory in the sky with 7-day markers. The retrograde loops are caused by parallax from Earth's annual motion around the Sun. The most movement occurs when the comet is closest to Earth.

| width1 = 275

| image2 = Comet_2019_Y4_ATLAS_from_Catalonia.gif

| caption2 = Animation of C/2019 Y4 (ATLAS) imaged over 10 minutes on March 28, 2020

| width2 = 200

| image3 = Comet Atlas Observed on April 08,2020.gif

| caption3 = C/2019 Y4 (ATLAS) as imaged on April 8, 2020. Note its faded appearance resulting from its disintegration.

| width3 = 315

}}

Gallery

File:Comet blast from the past.jpg|{{center|This pair of NASA/ESA Hubble Space Telescope images of comet C/2019 Y4 (ATLAS), taken on April 20 and April 23, 2020, reveal the breakup of the solid nucleus of the comet.}}

References

{{reflist|refs=

JPL Horizons barycentric solution for epoch 1950 (before entering planetary region)

Goto [https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2019Y4 JPL Horizons]

Ephemeris Type: Orbital Elements

Center: @0 (Solar System Barycenter)

Time Span: 1950-01-01 to 2050-01-01 and Step Size: 100 years

1950-Jan-01 is "PR= 1.76E+06 / 365.25 days" = 4818 years

{{cite journal

| author1= D. C. Jewitt

| title= Destruction of Long-period Comets

| url= https://iopscience.iop.org/article/10.3847/1538-3881/ac886d/pdf

| journal= Astronomical Journal

| year= 2022

| volume= 164

| issue= 4

| pages= 158–166

| bibcode= 2022AJ....164..158J

| arxiv= 2208.04469

| doi= 10.3847/1538-3881/ac886d

| doi-access= free }}

{{cite news

|last1=Ye |first1=Quanzhi |last2=Zhang |first2=Qicheng

|title=ATel #13620: Possible Disintegration of Comet C/2019 Y4 (ATLAS)

|publisher=The Astronomer's Telegram

|date=April 6, 2020

|url=http://www.astronomerstelegram.org/?read=13620

|access-date=April 6, 2020}}

{{cite web

|title=Comet Observation database (COBS)

|last1=Ghosh

|first1=Trinankur

|url=http://www.cobs.si/

|access-date=April 9, 2020

}} [https://cobs.si/analysis2?col=comet_id&id=1861&plot_type=0 (2019Y4 Chart)] {{Webarchive|url=https://web.archive.org/web/20200502173625/https://cobs.si/analysis2?col=comet_id&id=1861&plot_type=0 |date=May 2, 2020 }}

{{cite news

|author=Seiichi Yoshida

|title=C/2019 Y4 ( ATLAS )

|date=April 14, 2020

|url=http://www.aerith.net/comet/catalog/2019Y4/2019Y4.html

|access-date=April 17, 2020}}

{{cite news

|title=Solar Orbiter to pass through the tails of Comet ATLAS

|date=May 29, 2020

|url=http://www.esa.int/About_Us/ESAC/Solar_Orbiter_to_pass_through_the_tails_of_Comet_ATLAS

|access-date=May 29, 2020}}

{{cite news

|last1=Wood

|first1=Anthony

|title=ESA'S Solar Orbiter set for unexpected rendezvous with Comet ATLAS

|url=https://newatlas.com/space/solar-orbiter-rendezvous-comet-atlas/

|access-date=1 June 2020

|work=New Atlas

|date=May 29, 2020}}

}}

External links

{{JPL Small Body|id=1003655}}
[http://www.aerith.net/comet/catalog/2019Y4/2019Y4.html C/2019 Y4 (ATLAS) – Seiichi Yoshida]
[https://twitter.com/Yeqzids/status/1252256328841523200 C/2019 Y4 (ATLAS) – Hubble image]
[https://www.astro.umd.edu/~qye/shared/2019Y4_HST_20200420.png C/2019 Y4 (ATLAS) – Fragments (20 April 2020)] – Ye Quanzhi
[https://twitter.com/Komet123Jager/status/1261604833351675904 C/2019 Y4 (ATLAS) elongated (16 May 2020)] – Michael Jäger
[https://twitter.com/SungrazerComets/status/1266119728696827910 C/2019 Y4 (ATLAS) approaching perihelion in STEREO HI-1] (25 May 2020) – Karl Battams

Category:Non-periodic comets

20191228

Category:Discoveries by ATLAS

Category:Comets in 2019

Category:Comets in 2020

Category:Destroyed comets