Breakthroughs in black hole studies prove prize-worthy
Black holes were the subject of this year’s Nobel Prize in physics. Three astrophysicists shared the prize: Roger Penrose received half of the distinction for his “discovery that black hole formation is a robust prediction of the General Theory of Relativity,” and Reinhard Genzel and Andrea Ghez shared the other half for their “discovery of a supermassive compact object at the center of our galaxy.”
Genzel and Ghez worked in two separate teams on two continents to probe the center of the Milky Way. Those who have attended the popular “Black Holes: The Other Side of Infinity” show, which plays frequently at the William M. Thomas Planetarium at Bakersfield College, will be more familiar with Ghez since her work is a centerpiece of the program.
Ghez and Genzel use the largest telescopes in the world to hone in on the stars orbiting the supermassive black hole at our galaxy’s center. Ghez uses the 10-meter diameter Keck Telescope
in Hawaii and Genzel uses the Very Large Telescope facility in Chile, which has four 8-meter-diameter telescopes. They each had to develop techniques to peer through the gas and dust that blocks our view of the center as well as overcome the blurring effect of our turbulent atmosphere. They have been watching the stars that orbit very near the supermassive black hole since the early 1990s.
By tracking the positions of these stars very precisely, they were able to independently show that they must orbit a very compact object with a mass of about 4 million times the mass of the sun. It is the fact that the two groups were independent and competing against each other that put the discovery of the supermassive black hole at the galaxy’s center on a firm foundation. One star is so close that it takes less than 16 years to orbit the supermassive black hole in a very elliptical orbit. At closest approach the star is whipping by at 7,000 kilometers per second!
At our great distance of more than 27,000 light years from the galactic center, the sun takes about 214 million years to orbit the galaxy and the gravity the sun feels inside of its orbit is due to stars, gas, dust and dark matter. In fact, if the supermassive black hole was not present at all, the sun’s orbit would be essentially the same as it is now. While 4 million solar masses is a lot, the almost 100 billion solar masses of other material inside the sun’s orbit is a lot bigger!
REVISITING DATA AFTER DISCOVERY
Last month, I wrote about the surprising discovery of large quantities of phosphine found in Venus’ atmosphere. The phosphine in the atmosphere could be explained through biological processes in the clouds, so the discovery made national news. While more observations will be made by other research groups to verify the phosphine signal and while other groups will be trying to figure out geological processes to create the gas, another group is looking at archival data in Venus probes of decades ago to see if they may have overlooked something.
They’re looking at data from the NASA Pioneer Venus 2 mission, consisting of an orbiter and four atmospheric probes, which entered Venus’ atmosphere in December 1978. The largest of the probes had a mass spectrometer and a gas chromatograph to “sniff the air” (measure the atmospheric composition).
Looking at the data from
a fresh perspective has revealed evidence of phosphine along with methane and ammonia that could also be made by microbes, although the new analysis does not indicate the quantities of the phosphine nor whether or not it is biological in origin.
Large quantities of these molecules would not survive long in Venus’ atmosphere because the atmosphere’s chemistry quickly breaks it down and transforms it to something else. There must be some source continually pumping in the phosphine, methane and ammonia.
How could they have overlooked those detections? Rakesh Mogul from
Cal Poly Pomona, who led the team doing this new analysis of the Pioneer Venus 2 data, wonders if people were focused on just the gases that would survive in chemical equilibrium with Venus’ atmosphere because it was assumed that the hellish conditions of Venus would make it impossible for any type of life to upset the equilibrium.
He speculates that “perhaps (the researchers in 1978) were just waiting for other data to support the evidence of disequilibria in the minor species (such as phosphine). And maybe this is the time for it.”
It’s shocking that people could overlook something so obvious because of their preconceived notions of how things should be!
IN THE NIGHT SKY
The Orionid meteor shower peaks on Tuesday night into early Wednesday and the moon will be at waxing crescent, so it will set early in the night. That will keep the sky dark enough to spot some extra meteors. On Halloween, we’ll have a blue moon, which is the second full moon in the same month.