NEWS – Astronomers from the Indian Institute of Astrophysics (IIA) identified a vampire star in the star cluster M67, located in the constellation Cancer.

Vampire stars, also known as blue straggler stars (BSS), challenge simple stellar evolution models and exhibit traits typical of younger stars.

KEY FINDINGS

• Rejuvenation Process: The vampire star rejuvenates by siphoning material from a companion star in a binary system.
• Detection Tools: Data from the UltraViolet Imaging Telescope on AstroSat, India’s dedicated space observatory, was crucial for this discovery.
• Star Studied: The vampire star identified is WOCS 9005, located in M67.

HOW VAMPIRE STARS WORK

• Vampire Star: Typically a compact, hot star (white dwarf, neutron star, or black hole).
• Donor Star: Larger, cooler star (main-sequence or red giant).

Process:

• The vampire star’s strong gravity attracts material from the donor star.
• Material forms an accretion disk around the vampire star.
• Transferred material increases the vampire star’s mass and energy output.

Types of Vampire Stars:

1. Algol-type Binaries: Main-sequence donor star with a white dwarf vampire star.
2. Cataclysmic Variables: White dwarf vampire star with a main-sequence or red dwarf donor star.
3. X-ray Binaries: Neutron star or black hole vampire star with a main-sequence or red giant donor star.

Effects on the Donor Star:

• Mass Loss: Donor star loses material to the vampire star.
• Orbital Period Changes: Altered by the mass transfer process.
• Increased Temperature and Luminosity: Donor star may become more luminous and hotter.
• Eventual Engulfment: In some cases, the donor star may be entirely engulfed by the vampire star.