NASA astronomers have claimed that the Milky Way has 1.5 trillion times more mass than the Sun, earlier this year. However, new research has implied that the galaxy could be, in fact, much thinner than scientists have previously believed.
The Milky Way holds a minimum of 200 billion stars, even though some astronomers suggest the numbers could go as high as 400 billion. In March this year, a NASA paper based on observations collected from Hubble Space Telescope suggested an approximate weight of the Milky Way.
The NASA research, which was conducted together with the European Space Agency (ESA), discovered that the galaxy weighs a spectacular 1.5 trillion solar masses. A recent paper, however, pre-published on the server arXiv on December 9th, has implied that the Milky Way is way slimmer.
The Puzzling Cause
The pre-published paper, titled ‘A Robust Estimate of the Milky Way Mass From Rotation Curve Data,’ says that the Milky Way weighs approximately 890 billion solar masses or is 890 billion times heavier than our Sun.
It also measures the width of the galaxy, which is claimed to be about 250,000 light-years. This means that the Milky Way is approximately 1,469,656,300,000,000,000 miles wide. Even so, there seems to be a slim consensus on the galaxy’s weight. Previous estimates have pinned the number between 500 billion and 3 trillion solar masses.
Back in March, astronomer Roeland van der Marel said: “We want to know the mass of the Milky Way more accurately so that we can put it into a cosmological context and compare it to simulations of galaxies in the evolving universe. Not knowing the precise mass of the Milky Way presents a problem for a lot of cosmological questions.”
The stars count in the galaxy also happens to have a rather insignificant effect on the galaxy’s weight. A lot of its heaviness is assigned to the enigmatic substance known as dark matter.
Impossible to Calculate
Another cause of mass in the Milky Way is Sagittarius A*, which is a supermassive black hole located at the core of the galaxy. The black hole is believed to weight approximately 4 million times more than the Sun.
The pre-published research utilized a rotation curve, based on the activity of other stars and stellar gases that sway through the Milky Way. The scientists rutted the orbiting movements of the stellar bodies against the forces of gravity to estimate the masses of the bodies they were analyzing. When the puzzle of the dark matter was considered, which took approximately 93 percent of the galaxy’s mass, the research ended up with the result: 890 billion solar masses.
The researchers wrote: “We have used rotation curve data to estimate the dark and total mass of the Milky Way and performed a careful assessment of the robustness of these estimates.”
Even so, because of our location inside the Milky Way, it is extremely difficult to make precise measurements. Astronomers have it easier to measure the mass of close objects such as the Andromeda galaxy because they can be observed in their entirety.