2020 Nobel Prize in Physics awarded for research on Milky Way’s supermassive black hole

The central parts of our Galaxy, the Milky Way, as observed in the near-infrared with the NACO instrument on ESO’s Very Large Telescope. By following the motions of the most central stars over more than 16 years, astronomers were able to determine the mass of the supermassive black hole that lurks there.
Credit:ESO/S. Gillessen et al.

Reinhard Genzel and Andrea Ghez have jointly been awarded the 2020 Nobel Prize in Physics for their work on the supermassive black hole, Sagittarius A*, at the center of our galaxy. Genzel, Director at the Max Planck Institute for Extraterrestrial Physics in Germany, and his team have conducted observations of Sagittarius A* for nearly 30 years using a fleet of instruments on European Southern Observatory (ESO) telescopes.

Genzel shares half of the prize with Ghez, a professor at the University of California, Los Angeles in the US, “for the discovery of a supermassive compact object at the center of our galaxy”, with the other half awarded to Roger Penrose, professor at the University of Oxford in the UK, “for the discovery that black hole formation is a robust prediction of the general theory of relativity.” 

“Congratulations to all three Nobel laureates! We are delighted that the research on the supermassive black hole at the center of our galaxy has been recognized with the 2020 Nobel Prize in Physics. We are proud that the telescopes ESO builds and operates at its observatories in Chile played a key role in this discovery,” says ESO’s Director General Xavier Barcons. “The work done by Reinhard Genzel with ESO telescopes and by Andrea Ghez with the Keck telescopes in Hawaii has enabled unprecedented insight into Sagittarius A*, which confirmed predictions of Einstein’s general relativity.”

ESO has worked in very close collaboration with Genzel and his group for around 30 years. Since the early 1990s, Genzel and his team, in cooperation with ESO, have developed instruments designed to track the orbits of stars in the Sagittarius A* region at the center of the Milky Way. 

They started their campaign in 1992 using the SHARP instrument on ESO’s New Technology Telescope (NTT) at the La Silla Observatory in Chile. The team later used extremely sensitive instruments on ESO’s Very Large Telescope (VLT) and the Very Large Telescope Interferometer at the Paranal Observatory, namely NACO, SINFONI and later GRAVITY, to continue their study of Sagittarius A. 

In 2008, after 16 years of tracking stars orbiting Sagittarius A*, the team delivered the best empirical evidence that a supermassive black hole exists at the center of our galaxy. Both Genzel’s and Ghez’s groups accurately traced the orbit of one star in particular, S2, which reached the closest distance to Sagittarius A* in May 2018. ESO undertook a number of developments and infrastructure upgrades in Paranal to enable accurate measurements of the position and velocity of S2.

The team led by Genzel found the light emitted by the star close to the supermassive black hole was stretched to longer wavelengths, an effect known as gravitational redshift, confirming for the first time Einstein’s general relativity near a supermassive black hole. Earlier this year, the team announced they had seen S2 ‘dance’ around the supermassive black hole, showing its orbit is shaped like a rosette, an effect called Schwarzschild precession that was predicted by Einstein.

Genzel and his team are also involved in the development of instruments that will be installed on ESO’s Extremely Large Telescope, currently under construction in Chile’s Atacama Desert, which will enable them to probe the environment even closer to the supermassive black hole.

April meeting canceled

coronavirus covid-19 credit:CDCThe Cleveland Metroparks System’s Nature Centers are closed in an effort to control the spread of the novel coronavirus and COVID-19 disease. The monthly meetings of the Cuyahoga Astronomical Association take place at the Rocky River Nature Center which is affected by the park facility closure, therefore canceling the club’s April meeting.

Our meetings have become very popular, filling the nature center’s main meeting room with closely-spaced audience members — a potentially risky situation for contagious disease spread.

The CAA is willingly cooperating in efforts to prevent the spread of the novel coronavirus in the period of this spring’s Public Health Emergency. COVID-19 is a serious disease and it is only prudent, if disappointing, for some events to be called off. For more information on this public health issue, visit the Ohio Department of Health’s website.

In the mean time, stay healthy and work to prevent the spread of COVID-19 to others; the sooner it stops, the sooner we can get back to normal.

January 14 Meeting: New Horizons at Ultima Thule

Image: Artist's impression of the New Horizons spacecraft encountering a Kuiper Belt Object.
Artist’s impression of the New Horizons spacecraft encountering a Kuiper Belt Object. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

Kai Getrost, CAA member and member of the NASA MU69 Occultation Team, will be program presenter at the January 14 meeting of the Cuyahoga Astronomical Association (CAA). Getrost will discuss the latest news about what we’ve learned, how we got there, and how he was involved in the mission on three science trips to South America.

This image taken by the Long-Range Reconnaissance Imager (LORRI) is the most detailed of Ultima Thule returned so far by the New Horizons spacecraft. It was taken at 5:01 Universal Time on January 1, 2019, just 30 minutes before closest approach from a range of 18,000 miles (28,000 kilometers), with an original scale of 730 feet (140 meters) per pixel. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
This image taken by the Long-Range Reconnaissance Imager (LORRI) is the most detailed of Ultima Thule returned so far by the New Horizons spacecraft. It was taken at 5:01 Universal Time on January 1, 2019, just 30 minutes before closest approach from a range of 18,000 miles (28,000 kilometers), with an original scale of 730 feet (140 meters) per pixel. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The successful January 1 flyby of Kuiper Belt Object 2014 MU69/Ultima Thule came after extensive work by the scientists and technicians running the New Horizons mission. Largely unknown, invisible to the public, were efforts on the part of others to accurately locate the spacecraft’s target of opportunity subsequent to Pluto. Teams of astronomers were dispatched with portable telescopes and computers to observe and time occultations of stars by the invisible (it’s only about 20 miles long and is 4 billion miles away) target object; the exact location and improved orbital information of Ultima Thule was derived from those observations. Occultation refers to the moment the light from a distant star is blocked by an object nearer the observer.

The CAA’s monthly meetings are held on the second Monday of every month (except December) at 7:30 PM at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks. Meeting programs are open to the public.

Following the presentation and a brief social break, the club will conduct its membership business meeting.

Upcoming programs….

The Cuyahoga Astronomical Association (CAA) does not hold a General Meeting in December but that doesn’t mean nothing is happening over the winter months! Here are descriptions of programs planned for the CAA’s upcoming meetings:

January 8, 2018
“Journey to Another Solar System!”
Research astronomer and host of WKYC’s “In The Sky” Jay Reynolds will discuss how scientists are working now on a project to send high-speed probes to our nearest star (beyond our own Sun), with data results in less than 40 years of launch!

February 12, 2018
“Parallax: How we measure the distance from us to the stars!”
Club member and self-professed astronomy nerd Tim Campbell will follow Jay Reynolds’s January presentation by showing how through history, humans used cleverness, a basic principle of vision, and a succession of instruments to go from calculating the throwing distance to food to calculating just how far away those little dots in the nighttime sky really are!

March 12, 2018
“Astrophotography and other Cool Pictures”
Club members Alan and Gale Studt will present photos featuring starry night landscapes, panoramas, and star trails blended with earthly landscapes! For the technically curious, Alan will go over his gear and basic procedures. Plus music and more!

May 14, 2018
“The Inflationary Hot Big Bang Theory”
The universe is 13.7 billion years old and our best current understanding of the its origin is called the Big Bang Theory. Gary Kader, Director of the Burrell Memorial Observatory at Baldwin Wallace University, will present a lecture on the science and history of the Big Bang Theory, taking us back to within a trillionth of a second after that beginning.

June 11, 2018
“Telescope Show and Tell”
Tonight various club members will display their favorite telescopes and explain why, how, and “how much!”

CAA’s monthly meetings are held on the second Monday of every month (except December) at 7:30 PM at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks.