New Delhi: The Hubble Space Telescope has captured an image of the dusty spiral galaxy designated as NGC 4414, at a distance of 51 million lightyears from the Earth in the constellation of Coma Berenices. The flagship deep space observatory has previously imaged the same galaxy in 1995 and 1999, and was one of the targets of observations to determine the distances to galaxies. The galaxy contains Cepheid variable stars that have predictable changes in brightness, and act as cosmic distance markers because of the inverse square law of light. Measuring cosmic distances is a challenge because of the lack of context, and can be compared to eyeballing the distances to cities on the ground from an aircraft, at night.
As Cepheid variable stars can be used to reliably determine cosmic distances, they are known as standard candles, and are used to build a cosmic distance ladder, allowing scientists to map galaxies as increasingly greater distances. The Hubble Space Telescope has been used to observe Cepheid variable stars, like those that reside in 4414, that not only allows scientists to precisely measure the distances to galaxies, but also better understand the distribution of dark matter, and the rate at which the expansion of the universe is accelerating.
A dusty spiral galaxy
NGC 4414 is a nearly face-on spiral galaxy with well-defined spiral arms. There are significant amounts of dust in the galaxy, which are the reddish brown strands. These are clouds of gas and dust that are the raw material from which baby stars are born. In the fringes of the galaxy are blue regions that mark the presence of energetic young stars. The material from across the galaxy is spiraling inwards, towards the core of NGC 4414, where a supermassive black hole lurks. The observations by Hubble have also allowed scientists to determine the age of the universe, which is 13.7 billion years.
