FAQs

Below you will find a list of FAQs asked from us in public events and outreach activities. Please do not hesitate to send us any questions that you have regarding this project or about astronomy in general and we will include it here.

 


Q. What does an astrophysicist do?
A. We study objects in space (planets, stars, galaxies) and try to figure out how they work.


Q. How many stars are there in our Galaxy?
A. It has been estimated that there are about 400 billion stars in our Galaxy.


Q. What are stars made of?
A. Primarily Hydrogen, which is converted to Helium and then heavier elements over the course of a stars lifetime via nuclear fusion.


Q. Are all stars the same?
A. Nope! Stars can be anywhere between 150 and 0.1 times the mass of our own Sun.


Q. How are stars made?
A. There are very large clouds made up of gas and dust in our Galaxy (called ‘Giant Molecular Clouds’) which accrete more gas and dust over time. Eventually gravity causes these clouds collapse and form many stars which are typically clustered together (we call these ‘star clusters’).


Q. So what is the StarFormMapper project?
A. StarFormMapper (SFM) aims to combine data from two of ESA’s major space missions, Gaia and Herschel, together with ground based facilities, to constrain the mechanisms of massive star and star cluster formation.


Q. ..and Gaia is?
A. Gaia is a space observatory operated by the European Space Agency (ESA). Gaia was launched in December 2013. During the course of its 5 year mission, it will observe around 1 billion objects (mainly stars) which translates into 0.5 percent of all stars in the Galaxy. While this might seem like a very small fraction, astronomers are able to do some exciting science even with this tiny fraction and put constraints on the formation and evolution theories of stars and the Milky Way galaxy.


Q. What about Herschel?
A. Herschel was a space observatory operated by the European Space Agency (ESA). It operated between 2009 and 2013. During the course of its 4 year mission, it observed objects in our solar system, stars in our Galaxy and other Galaxies. Unlike Gaia, Herschel observed a special kind of light from these objects known as Infrared.


Q. Ok…so what is a space observatory?
A. Space observatories are like ground based observatories, but are in space! The quality of the images taken by ground based observatories are hampered by the Earth atmosphere. As a result, by sending observatories to space the effect of atmosphere is eliminated which leads to a significant improvement to the quality of the images.


Q. I hear that astronomers sometimes talk about the “magnitude of stars”. What is that?
A. The magnitude of a star is a measure of how bright it is. In astronomy, we define two types of magnitudes for stars: apparent magnitude (how bright it appears when we observe it) and absolute magnitude (how bright it really is). The apparent magnitude of a star depends on [1] its mass (the more massive the star, the brighter it really is) and [2] its distance from Earth. The magnitude of a star can be any number and conversely, the smaller its value the brighter the star! For example, a star with a magnitude of -5 is much brighter than a star with a magnitude of 10.


Q. How are the absolute magnitudes of stars measured?
A. It is the how bright the star would be if it was located at a distance of 10 parsecs from the Earth. A parsec (pc) is a unit of measuring distance in astronomy and approximately equal to 3.1×1017 meters or 3.26 light-years.


Q. Why do you measure distances in parsecs and not meters?
A. The distance to astronomical objects is so large that meters or even kilometres are too small a unit – its like trying to measuring your height in millimetres. For example, Proxima Centauri is the nearest star to the Sun at 1.3 parsecs away (40,000,000,000,000,000 meters)!


 

Can’t find the answer to your question? Ask an Astrophysicist!