A recent study led by IUCAA (with Nobel Prize winner Adam Riess as a co-author) has utilized Mira variable stars to determine the Hubble constant with a precision of 3.7%

What it represents?

Mira variables are fascinating, oscillating red giant stars whose luminosity changes periodically because of the expansion and contraction phases in their outer layers.

Uncovering:

The prototype star Mira (Omicron Ceti) was discovered to be variable in 1596 by David Fabricius and later examined in the 17th century, establishing it as the first acknowledged variable star.

Attributes:

Period of brightness fluctuation: 100–1,000 days.

Surface temperature: approximately 3,000 K (around half of the Sun's surface temperature).

Situated in a late stage of evolution (expiring giant stars).

Robust period–luminosity connection, akin to Cepheid stars.

Types rich in oxygen (employed in the research) are less influenced by metallicity, resulting in clearer luminosity calibration.

Importance:

Act as "standard candles" in astronomy—assisting in measuring cosmic distances.

Offer a fresh independent calibration for Type Ia supernovae in the extragalactic distance scale.

Essential in ascertaining the Hubble constant and resolving the Hubble tension (discrepancy in the Universe's expansion rate observed through early compared to late-Universe techniques).