In the article titled “Gravity-lensed supernova magnifies understanding of universe” it talks about how scientists have discovered a Type la supernova that exploded billions of years ago. It is positioned behind a galaxy two billion light years away that is acting like a gigantic gravitational magnifying glass split the star into four bright images in four different parts of the sky. Astronomers believe that since its the first supernova to be seen by gravitational lensing, it can provide a lot of useful information into how the universe is expanding. Supernova IPTF16geu was identified last September and was speculated to be one billion light years away, but due to spectral analysis showed that it was not only a Type la Supernova, but four times further than first estimated. Type la Supernova has the same luminosity and also the same properties to provide insight to astronomers on how bright they are and how far away they are as well. If astronomers know the distance and can compare the travel of light from lensing, they can calculate how fast the universe is expanding.
Stars are the key to understanding the universe, it is by studying the stars that astronomers determine their properties. To get the size of a star, usually involves estimating the distance to the star. Stars that are not to far away can have their distances measured using parallax. As the Earth moves around the sun, we see stars from a different vantage point every night. If we compose where we see a nearby star, as seen in a background of very faraway stars, at one observation and six months later, we may find that its visible position has shifted a tiny amount relative to the faraway background stars. By knowing the size of the Earth’s orbit and this little angle, astronomers can estimate the distance to a star. By knowing the distance to the star and how bright it seems to us, astronomers can calculate the total light energy coming from the star per unit time.
In our lecture tutorial book on page 41 we did an exercise on star parallax. We learned that we can obtain the distance to nearby stars by using their parallax angles. The parallax angles are measured in units of arcseconds. The article i choose showed how astronomers examine the properties of stars to form a hypothesis of how the universe works.
This conceptual objective was interesting to learn about. I now have a better understanding of how astronomers view properties of stars. Learning about the past and future of our universe in intriguing to me. I also liked how the article included pictures because i am more of a visual learner so it helped me comprehend the topic better.