The Absolute Cosmos: Earth is significantly closer to Sagittarius A* than previously thought
A new map of Milky Way has somewhat changed our Solar System’s position in our galaxy. Newly created map has placed our solar system way closer to our galaxy’s supermassive black hole, Sagittarius A* (Sgr A*).
However, this is not something one should worry about as we are not moving closer to Sagittarius A*. The new map has identified our solar system’s position in Milky Way more accurately.
The new map very effectively shows that how difficult is to map a galaxy in three dimensions from sitting inside it. While it is quite easy to map the two dimensional co-ordinates of celestial objects but calculating distances to these objects is a tough job.
Distances play a key role in measuring the brightness of celestial objects. One such example is Betelgeuse, which according to scientists is closer to Earth than previously thought. Meaning it is neither as big nor as bright as previously thought.
Scientists are working hard in resolving those distances more accurately in order to refine the three dimensional map of our galaxy. They are conducting the surveys using best available technology of modern times.
One such survey is VERA radio astronomy survey conducted by Japanese VERA collaboration. VERA represents VLBI (Very Long Baseline Interferometry) Exploration of Radio Astrometry.
VERA functions by using the same technique that was used by the Event Horizon Telescope which generated the first ever direct image of a black hole’s shadow.
Designed to calculate the distances to radio emitting stars by measuring their parallax, VERA became operational in 2000.
It monitors those stars for over a year to watch how their position changes relative to stars which are much farther away as Earth circles our Sun. This change in position can then be used to measure how far a star is from our planet.
VERA has a resolution of ten millionths of an arcsecond, which can produce highly accurate measurements. This is exactly what scientists have used to re-define our Solar System’s position in the Milky Way galaxy.
They used the first VERA Astrometry Catalog (delivered earlier this year) of ninety nine celestial objects and various other observations to create a position and velocity map of those objects. By using this map, scientists calculated the galactic centre’s position.
Distance to the galactic centre was defined to 27,700 light years by the International Astronomical Union in 1985. In 2019, the GRAVITY collaboration redefined the distance and found it closer at 26,673 light years away.
And now VERA observations bring it even more closer at 25,800 light years. Solar System’s speed was also found faster at 227 kilometres per second, which previously was thought to be 220 kilometres per second.
How minute the change may be, yet it could effect the way we look activities around galactic centre. Eventually, helping scientists to paint more precise image of the complex movements and interactions around Sagittarius A*.
In the meantime VERA collaboration is continuously making observations of objects in Milky Way. It will be joined by even more larger survey East Asian VLBI Network. Together these projects will provide measurements of extraordinary accuracy.
For more information: The First VERA Astrometry Catalog