For the first time, astronomers combined ground-based observations with data from a space telescope to measure the distance to a stellar object, which was discovered through microlensing.
Microlensing occurs when a massive object, such as a dim star, a brown dwarf, a planet, or even a black hole, passes in front of distant stars. As predicted by Einstein's theory of relativity, when the planet drifts through our galaxy, its gravitational field will be slightly distorted by space-time.
From the point of view of the Earth, when the planet drifts in front of a distant star, starlight can bend around the planet, creating a lensing effect. Like a magnifying glass in front of a light bulb, a gravitational lens briefly makes the light from the star brighter.
In our galaxy there are billions of stars, free-drifting planets, brown dwarfs and dim stars, so it’s impossible to predict when and where microlensing will occur. Of course, if you do not have a celestial object that will be located between us and the star.
Since the detection of microlensing events is a good thing, astronomers have developed several ground-based survey networks that use wide-angle telescopes for continuous monitoring of large areas of the sky. When an event is detected, an automated alert system alerts the astronomical community to maximize data collection. This is surprising, but there is one thing that is missing in the analysis of a microlensing event - we have no information about the distance from the Earth to the lens.
But now, combining the rapid response of the network of ground-based telescopes and the NASA Spitzer telescope, astronomers presented a new method aimed at calculating the distance to cosmic lenses.
A new report published in The Astrophysical Journal, astronomer Jennifer Yee from the Harvard-Smithsonian Center for Astrophysics (CFA), Massachusetts. which was discovered with a 1.3-meter Warsaw telescope at the Las Campanas Observatory, Chile.
Team Yi seized on the opportunity to use Spitzer to focus on transitional enlightenment. Both telescopes recorded the light curve of the event.
Spitzer rotates around the Sun at the same distance as the Earth, but lags behind Earth by about one sixth of its orbital trajectory around the Sun. This unique opportunity allowed astronomers to create a baseline in astronomical trigonometry.
As a rule, when measuring the distance to objects located for a set of light years, astronomers take measurements for 6 months. Since the Earth rotates around the Sun at a distance of 1 a. e (astronomical unit), this 6-month delay between observations forms a baseline of 2 a. e. If you know the baseline and the angular displacement of a celestial object, you can estimate the distance to this object. This method is known as parallax measurement. By simultaneously measuring the same microlensing event, astronomers were able to estimate the distance to the object OGLE-2014-BLG -0939. According to preliminary data, the distance is estimated at 10,200 (+/- 1300) light years.
Much work needs to be done to characterize the nature of this “star lens”, but the method to measure the distance to it is obviously a very powerful tool.