New York: While it is not possible to put the entire Milky Way on a scale, that has not deterred astronomers from trying to make measurements of our home galaxy. According to a new “robust” estimate of Milky Way’s mass measurement, it is about 890 billion times the mass of our Sun.
That is equal to 1.8 tredecillion kilograms, a tredecillion being a 1 with 42 zeros after it, which amounts to about six billion billion billion elephants, Live Science reported.
The estimate in the new study, made available to the arXiv database this week, is inferred via a Bayesian approach from tracers of the circular velocity in the disk plane and stars in the stellar halo.
“We use the rotation curve method to determine the dark matter density profile, together with the total stellar mass, which is constrained by surface stellar density and microlensing measurements,” said the study.
The researchers estimate that the mass of Milky Way’s dark matter — an invisible and mysterious substance that acts like scaffolding throughout the universe and keeps the stars in their galaxies — is equal to about 830 billion times the mass of our Sun, or about 93 per cent of its total mass, said the report.
The researchers evaluated the robustness of their result against various possible systematics and past research work and found the conclusions to be in “good statistical agreement” with those results.
Another study, published earlier this year in the The Astrophysical Journal, estimated that the Milky Way weighs in at about 1.5 trillion solar masses (one solar mass is the mass of our Sun).
The researchers in this study used NASA’s Hubble Space Telescope and the European Space Agency’s Gaia satellite to make the measurements.
Only a few per cent of this is contributed by the approximately 200 billion stars in the Milky Way and includes a 4-million-solar-mass supermassive black hole at the centre.
Most of the rest of the mass is locked up in dark matter, said the study.
Earlier research dating back several decades used a variety of observational techniques that provided estimates for our galaxy’s mass ranging between 500 billion to 3 trillion solar masses, according to NASA.
Prasanta Patnaik