In a significant development, scientists from the SN Bose Centre for Basic Science (SNBCBS) observed an imploding novae named Nova V1280 Scorpii. What was noteworthy about this discovery was that a thick dust enveloped it a month after the occurrence and remained there for approximately 250 days.
Getting Acquainted with Novae
A nova signifies a powerful explosion on the stellar surface, which temporarily increases the brightness level immensely and slowly fades over weeks or months. This event occurs in a binary system comprising a white dwarf and a main sequence star. A binary star system is defined as a common center of mass around which two stars orbit. Out of the two stars, the brighter star is classified as the primary star and the dimmer one as the secondary.
White Dwarfs: Energy-Exhausted Stars
White dwarfs are stars lacking hydrogen once used as nuclear fuel. Characterized by exceptionally high density, a typical white dwarf is half the size of our Sun. Interestingly, its surface gravity is 1,00,000 times more than that of Earth.
Cosmic Dust: Interstellar Matter Traces
Cosmic dust, composed of tiny particles of solid material, floats in the space located between the stars. The formation of extraterrestrial dust in the hostile novae ejection environment has puzzled scientists for years. Earth experiences a daily fall of hundreds of kilograms of such cosmic dust.
Breakthrough Findings: Dust Composition in Novae
The scientists’ approach involved constructing straightforward models to measure dust parameters such as hydrogen density, temperature, luminosity, and elemental abundances for both the pre-dust and post-dust phase. Notably, high abundance levels of certain elements, including carbon, nitrogen, and oxygen, were detected. Additionally, a mix of small amorphous carbon dust grains and large astrophysical silicate dust grains was found.
Unlike the typical interstellar dust that takes nearly a few thousand years to form, dust formation in novae ejecta is not a regular phenomenon. It has only been seen in a few novae around 30 to 100 days post-outburst. This unusual occurrence offers a valid opportunity to probe the dust formation process in novae.
Remarkably, in the pre-dust phase, an abundance of isotopes of certain elements like carbon, nitrogen, and oxygen was found. Similarly, the post-dust phase showed a mix of amorphous carbon dust grains and large astrophysical silicate dust grains in the ejecta.
Significance of Cosmic Dust Study
Space-dust collisions potentially have the power to transport organisms across vast distances between planets, giving life a chance to thrive on different planets. Consequently, the study of nova dust could help understand the properties and processes associated with cosmic dust.
The research team suggests that the expanding dust shell of V1280 Scorpii Nova will eventually integrate with interstellar matter as it continues to expand. Although this may take a few thousand years, it’s relatively brief in terms of the cosmic timescale.
Musings on Past UPSC Civil Services Examination Questions
In question (2009), the correct option is S. Chandrashekhar, known for his groundbreaking work on the structure and evolution of stars. Chandrasekhar earned the Nobel Prize for Physics in 1983 in partnership with William A. Fowler. His calculation of the ‘Chandrasekhar Limit’, a theoretical limit on the mass of White Dwarf Stars is particularly renowned. Demonstrating it using Albert Einstein’s Special Theory of Relativity and Quantum Physics Principles, he established that stars with mass less than 1.44 times the Sun’s mass become White Dwarfs after their nuclear fuel is exhausted. NASA named its third “Great Observatories” after Chandrasekhar, who also has an asteroid named in his honor.