Comets

Blogs about comets

Artist's impression of a dust-generating Kuiper Belt collision (Image courtesy Dan Durda, FIAAA)

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An article published in “The Astrophysical Journal Letters” reports a study of the presence of dust in the Kuiper Belt which suggests that it may be much more extended than previously thought or that there’s a second Belt outside the known one. A team of researchers used detections conducted with NASA’s New Horizons space probe’s Venetia Burney Student Dust Counter (VBSDC, or simply SDC) instrument to support these possibilities. That’s because current models indicate that dust density should decrease in the area where New Horizons is traveling, where detections are higher than expected.

Comet C/2014 UN271 (Bernardinelli-Bernstein)

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An article published in “The Astrophysical Journal Letters” reports a study on comet C/2014 UN271 (Bernardinelli-Bernstein) conducted thanks to observations made with the Hubble Space Telescope. A team of researchers also used previous observations to estimate that this comet’s nucleus is about 119 kilometers in diameter. This result confirms that it’s the largest known comet. The studies will continue even if it will remain very far from Earth also because it almost certainly comes from the Oort cloud.

Fragments of comet C/2019 Y4 (ATLAS) seen by Hubble

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An article published in the “Astronomical Journal” reports the results of a study on comet C/2019 Y4 (ATLAS) whose conclusion is that it’s a fragment of a larger comet whose passage could have been seen on Earth about 5,000 years ago. A team of researchers led by astronomer Quanzhi Ye of the University of Maryland in College Park used observations conducted with the Hubble Space Telescope to examine this comet and its orbit. In fact, there are now various fragments and it’s possible that the progenitor gave rise to an entire family of comets. Amateur astronomer Maik Meyer identified a correlation with C/1844 Y1, nicknamed the Great Comet of 1844.

The giant comet C/2014 UN271 (Bernardinelli-Bernstein)

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The Las Cumbres Observatory has captured a new image of the giant comet C/2014 UN271 (Bernardinelli-Bernstein) that shows its activity despite its considerable distance given that it’s far beyond Saturn’s orbit. The information collected also by looking into archive images such as the ones that allowed to identify it in an image from 2014 is useful to better understand its characteristics. In particular, initial estimates suggested that its diameter was at least 100 kilometers, three times the largest known comet, but these are estimates based on the absence of a coma. C/2014 UN271 will remain far from the Sun, arriving close to Saturn’s orbit at the beginning of 2031, so it can only be admired with telescopes but it could still be very interesting because it probably comes from the Oort cloud.

Comet C/2016 R2 (PANSTARRS) and its spectrum (Image ESO/L. Calçada, SPECULOOS Team/E. Jehin, Manfroid et al.)

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Two articles published in the journal “Nature” report different studies on the materials present in the atmospheres of comets, which appear to contain iron and nickel even in the ones far from the Sun. Jean Manfroid, Damien Hutsemekers, and Emmanuel Jehin used data collected by the UVES spectrograph of ESO’s VLT in Chile to analyze the atmospheres of various comets detecting the presence of both iron and nickel. Piotr Guzik and Michał Drahus used the X-shooter spectrograph, also of the VLT, to examine in particular the interstellar comet 2I/Borisov detecting the presence of nickel. They were surprising results because the sublimation of heavy metals was thought possible only near the Sun.