New comet 2I/Borisov visits the solar system
By Amanda Jermyn

Back in August, using his own homemade telescope, Crimean amateur astronomer Gennady Borisov first spotted a fuzzy dot of light following a strange path through the night sky. It turned out to be only the second comet from another star ever to be observed entering our solar system. Back in 2017 comet Oumuamua, was the first. The newly discovered comet has been named 2I/Borisov, with the ‘I” for interstellar and the “2” acknowledging its status as the 2nd such object ever found.

Also dubbed “The Christmas Comet,” it will make its closest approach to the Sun on December 7th, after which it will begin its journey away from our star. At its closest it will be about 180 million miles from the Sun, roughly the same distance as it will be from Earth.

Comets are comprised of rocky particles, dust, water ice and frozen gases left over from when planets form in the outer regions of planetary systems. As a comet approaches its star it heats up, releasing gas to form an atmosphere called a coma, and sometimes a trail of dust called a tail. The glowing coma and tail help make it visible in the night sky. Comet 2I/Borisov has a greenish color, with an extended coma and short tail. With the aid of a telescope it should be visible in the southern skies for several months around its closest approach to the Sun.

Using telescopes on La Palma in the Canary Islands, astronomers led by Alan Fitzsimmons of Queen’s University Belfast have already detected cyanogen, a toxic gas often found in comets, in the gas cloud around 2I/Borisov. This marked the first time astronomers have ever detected gas emitted by an interstellar object. A subsequent study led by Theodore Kareta of Arizona University’s Lunar and Planetary Observatory detected diatomic carbon, a gaseous form of carbon often found in solar system comets. The cyanide gas and diatomic carbon would account for 2I/Borisov’s green glow. Perhaps the most interesting finding so far is that the comet’s gas, dust and nuclear properties are similar to those found in solar system comets. This suggests that the comets we see coming from interstellar space likely formed in a similar way to those in our own solar system.

So where did comet 2I/Borisov come from, and what set it off on its journey through space? A close encounter with a large planet can jolt a comet out of its orbit, sending it away from its star into interstellar space, so this may well have happened to 2I/Borisov. A recent study by astronomers from the A. Mikiewicz University and the Space Research Centre of the Polish Academy of Sciences suggests that this comet likely came from a binary star system called Kruger 60 located in the constellation Cepheus, about 13.15 light years from the Sun. It consists of two M-type stars, also known as Red Dwarfs, that orbit each other once every 44.6 years.

With the advent of more sensitive telescopes it seems likely that other such intriguing objects will be observed entering our solar system, unveiling yet more mysteries of the universe.

Join the Springfield Stars Club on Tuesday, November 26th at 7pm at the Springfield Science Museum for a talk by Adam Jermyn on ”Tides on Binary Stars,” how stars that orbit each other interact. Adam is a Research Fellow at the Flatiron Institute’s Center for Computational Astrophysics in New York. He was previously a Postdoctoral Scholar at the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara. He received his PhD in astronomy from Cambridge University, England, and his undergraduate degree in physics from the California Institute of Technology (Caltech). He has won numerous awards, including, most recently, the International Astronomical Union’s PhD Prize in the field of Stars and Stellar Physics. Adam graduated from Longmeadow High School in 2011 and was a member of the US Physics Team while in high school. He has been a member of the Springfield Stars Club since the age of five. Refreshments will be served, and the public is welcome. The meeting is free of charge for members, with a suggested donation of $2 per non-member.

Also, on Friday, December 6th at 7:30pm, the Stars Club and the Springfield Science Museum will host “Stars over Springfield,” an astronomy adventure for the whole family. Amateur astronomer Paul Cardone will present “New Mexico Nights Observatory Part II,” a live demonstration of operating an observatory by remote control. A fee of $3 for adults and $2 for children under 18 will be charged.