Space

Has October’s 2nd comet – the sungrazer Comet S1 – disintegrated?

A black circle blocks the sun. Plumes of light stream out from it. A comet flies into the image and disappears.
See the comet? Sungrazer comet C/2024 S1 (ATLAS) is coming in front below the sun in this image via the sun-observing SOHO spacecraft. The new imagery suggests the comet did not survive its run-in with the sun. Image via NOAA.

UPDATE October 28: So long, sungrazer comet Comet S1

In early October, it seemed as if we might have two bright comets this month. And – though it’s beginning to fade now – Comet A3 has performed beautifully in our evening skies. Meanwhile, we’ve heard less about the 2nd comet, C/2024 S1 (ATLAS), aka Comet S1. We knew it was supposed to reach its perihelion (closest point to the sun) on October 28, 2024. Now the latest imagery from the sun-observing SOHO spacecraft suggests that Comet S1 did not survive its run-in with the sun. On its approach to today’s perihelion, the once-promising sungrazer comet seems to vanish from the spacecraft’s field of view. Presumably, the comet has disintegrated.

While disappointing, the news comes as no surprise. Comet expert Karl Battams (@SungrazerComets on X) warned over the weekend that S1 wouldn’t survive its perihelion. And there were reports earlier this month that the comet began fragmenting as it came closer to the inner solar system.

Report of disintegration

Astronomers said on October 9, 2024, in The Astronomer’s Telegram that it appeared Comet S1 was disintegrating. They compared observations of Comet S1 from Australia’s Siding Spring Observatory on October 3 with observations from the South African Astronomical Observatory on October 8. The astronomers said the nucleus, or central ice ball of the comet, “appeared elongated and fainting” on October 8 compared to the October 3 images. They reported:

This finding suggests a possible fragmentation of the nucleus.

Despite the comet was still at a relatively ‘safe’ distance from the sun, it is possible that strong vaporization of a large amount of gas occurred which, together with the tidal or rotational forces acting on the comet’s nucleus, may have led to its fragmentation.

Black and white side by side of a comet and a thinner looking sungrazer comet.
These images show how Comet S1 (the fuzzy streak at center of each image) looked on October 3, 2024, compared to October 8, 2024. Astronomers said the image on the left shows the nucleus of the comet. And on the right, they said the nucleus of the comet is no longer clearly observable. Plus, the elongated appearance resembles that of Comet C/2019 Y4 (ATLAS) at the time of its breakup. Image via Siding Spring Observatory/ South African Astronomical Observatory/ The Astronomer’s Telegram.

Announcement of the new sungrazer comet

The ATLAS survey in Hawaii discovered another new comet that could become bright in Earth’s skies on September 27, 2024. First designated A11bP7I, its name officially became C/2024 S1 (ATLAS). Predictions for the comet had it reaching as bright as magnitude -5 to -7 when it comes closest to the sun, at perihelion, on October 28. Will that still happen? We’ll have to wait and see.

The Southern Hemisphere should have the best view before perihelion. After its close encounter with the sun (if it survived) it could put on a fantastic show for the Northern Hemisphere in the morning skies. It would definitely be something to wake up early for.

But it this comet is kaput, don’t forget about the OTHER comet in Earth’s skies right now. C/2023 A3 Tsuchinshan-ATLAS should now start to appear in your evening sky just after sunset.

A Kreutz sungrazer

The new sungrazing comet is part of the Kreutz sungrazers. These are comets that come perilously close to the sun, where they can disintegrate or, if we’re lucky, become fantastically bright. Many of the comets through history that have been given the name “Great” (for example the Great Comet of 1882, the Great Comet of 1106 and the Great Comet of 371 BCE) were all Kreutz sungrazers. More recently, Comet Ikeya–Seki in 1965 was a Kreutz sungrazer that became as bright as magnitude -11. That’s as bright as a 1st quarter moon.

Scientists believe Kreutz sungrazers all come from a big comet that broke up a couple of millennia ago. Most Kreutz sungrazers are small fragments, but this one may be larger than most.

Will it become as bright as Ikeya-Seki? Not likely. When the new comet was about 1 astronomical unit (AU) from the sun, it was about 4 to 5 magnitudes dimmer than Ikeya-Seki was at that distance.

Side by side of light streaks on a dark background with a blurry spot at center.
View at EarthSky Community Photos. | Filipp Romanov used the iTelescope at the Siding Spring Observatory in Australia to capture the new comet. Thank you, Filipp!

Orbit of C/2024 S1 (ATLAS)

A flat blue grid with Earth's orbit in it, and a long parabola with its sharp curve right at the sun.
In this space view, a grid of blue lines represents the ecliptic plane (plane of Earth’s orbit around the sun). The grid consists of squares that are 1 astronomical unit – one sun-Earth distance, 93 million miles or 150 million km – on a side. The diagram exaggerates Earth’s size by 500; the sun is shown at true size. The path of the sungrazer comet C/2024 S1 ATLAS is drawn for the last 3 months of 2024. The vertical lines represent the start of each new earthly month. The path is omitted for one day, October 28. That is the day the comet whips around the sun at perihelion (its closest point). Image via Guy Ottewell. Used with permission.

Bottom line: The new sungrazer comet gave us high hopes of a bright comet at the end of October. But it appears it has disintegrated during its close approach to the sun.

Via Spaceweather

Via Starwalk

Posted 
October 28, 2024
 in 
Space

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