Astronomers discover possible planets around cataclysmic variable stars

(ORDO NEWS) — The planet is able to influence the flow of matter from one star to the second, changing the brightness of their binary system. This makes it possible to notice planets revolving around cataclysmic variable pairs.

Cataclysmic variables are binary systems, and their brightness changes as one star moves around the other. However, sometimes such changes do not coincide with the orbital period of the system, which may indicate the presence of a planet invisible to telescopes.

This is the conclusion reached by the authors of a new article published in the journal MNRAS. Astronomers believe that anomalies in brightness will make it possible to detect new exoplanets even in such variable systems.

Cataclysmic variables are called stars, which from time to time abruptly change their brightness, flashing sharply, and then slowly fading away. They come in different types, but always consist of two stars orbiting each other.

One of them is much more massive, hotter and denser than its partner and gradually pulls its substance onto itself.

As a rule, such a pair is made up of white dwarfs (with an average mass of 0.75 solar and comparable in size to the Earth) and red dwarfs (with a mass of 0.1-0.3 solar and a diameter of about 0.2 solar diameters).

Moving from a red dwarf to a white dwarf, matter usually forms an accretion disk, which gets very hot and sometimes begins to radiate brighter than even the stars themselves.

From there, it falls to the surface of the white dwarf, and when enough matter accumulates on it, new thermonuclear reactions begin there, causing the variable to flare up sharply – on a scale of several hours or days.

After exhausting the “extra” reaction gas, the star gradually fades out to flare up again after several or even thousands of years.

However, if in such a system there is a third body invisible to telescopes, its gravity should affect the flow of matter from the donor star, and hence the radiation of the accretion disk.

The brightness of such cataclysmic variables can change, not coinciding with the period of revolution of a pair of stars around each other.

It is these objects – LU of the constellation Giraffe, QZ Serpens, V1007 Hercules and BK Lynx – that Carlos Chavez and his colleagues from the Autonomous University of Nuevo Leon in Mexico considered in their new work.

Their calculations showed that planet-like bodies could be present in at least two of these four systems.

Scientists believe that in the near future this approach will be used in the search for new exoplanets. The most popular transit method today allows you to notice distant planets by changing the brightness of their stars at those moments when the planets partially cover them, passing in their orbit.

In this case, the plane of rotation of the planet must be on the line of observation, otherwise the eclipse will not occur.

But changes in the brightness of cataclysmic variables do not depend on their orientation relative to us. Perhaps they will help discover many new exoplanets orbiting at all angles around such turbulent stellar pairs.

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