Heartbeat stars: A star with a heartbeat & without a magnetic field discovered

What is the news?

Scientists have discovered a peculiar binary star named HD73619 in the Cancer constellation, one of the closest open star clusters to the Earth. The star shows heartbeat but no signs of pulsations/vibrations activity, contrary to the norm of binary stars sporting both heartbeats as well as pulsations.

What are the heartbeat stars?

The name heartbeat comes from the resemblance of the path of the stars to an electrocardiogram of the human heart. Here, each star travels in a highly elliptical orbit around a common centre of mass. The distance between the two stars varies drastically as they orbit each other.

When the stars are at their closest, there is a sudden increase in the brightness, with amplitude going up to several parts per thousand. As they move apart, the light variation falls and becomes almost flat. This results in alternating peaks and troughs in their light curves.

The pulsation activity of the stars is due to oscillations in the component stars when they are the closest.

What are the findings by the scientists?

A team of 33 scientists from Aryabhata research institute of observational sciences (ARIES) carried out photometric and high-resolution spectroscopic observations of HD73619. It was found that HD73619 is the first member of heartbeat systems in binary chemical peculiar stars that do not show any positional activity at the closest approach.

Chemically peculiar stars are the ones that have an abundance of elements heavier than hydrogen and helium on the surface. The study also revealed an absence of a weak magnetic field, which reflect the unknown origins of the system.

What is the importance of the discovery?

It is important for the study of inhomogeneities due to spots in non-magnetic stars. It will help in the investigation of the origins of pulsational variability.

Source: This post is based on the article “A star with a heartbeat & without a magnetic field discovered” published in The PIB on 7th January 2022.