August 20, 2025

rchives (PRELIMS  Focus) SN 2023zkd Category: SCIENCE AND TECHNOLOGY Context:  Astronomers have observed a new type of supernova triggered by the violent interaction between a massive star and a black hole in a binary system, named SN 2023zkd. A massive star, at least 10 times the Sun’s mass, was locked in a tight orbit with a stellar-mass black hole. Over years, the black hole’s gravity stripped away the star’s outer hydrogen layer, exposing helium and causing abnormal brightening. As the orbit decayed, the gravitational stress reached a tipping point, leading to a supernova explosion that released more energy in a second than the Sun will emit in its lifetime. The black hole then consumed much of the stellar debris, becoming more massive. This is the first strong evidence that black holes can directly trigger supernovae in massive stars, not just influence them through accretion or mergers. It reshapes our understanding of how massive stars die and how black holes grow. The event was detected thanks to an AI-based system, which flagged unusual activity and prompted rapid follow-up observations. Archival data showed years of brightening prior to the explosion, confirming the gradual mass transfer process. The discovery highlights the role of black holes in catalyzing stellar deaths, the power of AI in astronomy, and provides new insights into the complex evolution of binary star systems. Learning Corner: Supernova A supernova is the catastrophic explosion of a star, resulting in a sudden, extremely bright outburst that may briefly outshine an entire galaxy. It represents the final evolutionary stage of certain stars and plays a critical role in enriching the interstellar medium with heavy elements (like iron, gold, uranium). Supernovae are key to the cosmic cycle of matter and are important markers for measuring cosmic distances (Type Ia). Types of Supernovae Type I Supernova Occurs in binary star systems, where a white dwarf accretes matter from its companion until it reaches the Chandrasekhar limit (~1.4 solar masses). Results in a thermonuclear explosion with no hydrogen lines in spectrum. Subtypes: Type Ia – Used as “standard candles” in cosmology for distance measurement. Type Ib and Ic – Collapse of massive stars stripped of hydrogen (Ib) and both hydrogen + helium (Ic). Type II Supernova Results from the core-collapse of a massive star (> 8 solar masses) after nuclear fuel exhaustion. Spectrum shows strong hydrogen lines. Produces either a neutron star or a black hole. Significance Enriches galaxies with heavier elements (stellar nucleosynthesis). Creates neutron stars, pulsars, or black holes. Provides tools to study dark energy and cosmic expansion (Type Ia).  SN 2023zkd: A New Class of Supernova Discovery & Uniqueness: Detected in July 2023 by the Zwicky Transient Facility, SN 2023zkd was not a typical stellar explosion. It is believed to be the strongest evidence of a black hole–triggered supernova, caused by the gravitational interaction between a massive star and its black hole companion. AI-based Early Detection: An AI system (Lightcurve Anomaly Identification and Similarity Search – LAISS) flagged its unusual light pattern months in advance, enabling astronomers to track the event in detail. Strange Pre-Explosion Behavior: The star displayed four years of continuous brightening before its final detonation, a highly unusual precursor not seen in ordinary supernovae. Double-Peaked Light Curve: Instead of one brightness peak, SN 2023zkd showed two separate re-brightening events after explosion—likely from the blast colliding with earlier ejected gas and then with more distant material. Cause of Explosion: Scientists suggest that as the star orbited closer to the black hole, intense gravitational stress stripped its mass and eventually triggered the explosion. Another theory is that the black hole shredded the star, and the debris collisions mimicked a supernova. In both cases, the black hole grew more massive. Scientific Significance: SN 2023zkd provides a new model of stellar death, showing how compact objects like black holes can induce supernova-like events. It also highlights the growing role of AI in astronomy for early detection and classification of rare cosmic phenomena. Source: REUTERS GST reforms Category: ECONOMICS Context : S&P Global Ratings has noted that India’s planned GST reforms, despite lowering tax rates and causing an initial revenue loss, are expected to boost long-term revenues by driving higher consumption. Estimates suggest a shortfall of about ₹85,000 crore initially, but rising demand could eventually add nearly ₹2 lakh crore in revenue. The reforms—moving towards a simpler two-slab structure of 9% and 18%—are expected to improve compliance, make accounting fairer, and support economic growth. HSBC adds that the GST revamp, along with a possible S&P credit upgrade and changes in global trade tariffs, could strengthen India’s fiscal discipline and investment climate. The success of these reforms, however, will depend on effective execution, coordination with the GST Council, and adjustments in revenue-sharing arrangements. Learning Corner: GST Council Constitutional Body: Established under Article 279A of the Constitution (via the 101st Constitutional Amendment Act, 2016). Composition: Chairperson: Union Finance Minister Members: Union Minister of State (Finance/Revenue) + Finance Ministers of all States & UTs with legislatures. Decision-Making: Decisions taken by 75% majority of weighted votes: Centre: 1/3rd weightage States: 2/3rd weightage Functions: Recommend GST rates, exemptions, thresholds, model laws, and special provisions for states. Decide on revenue sharing, dispute resolution, and simplification of compliance. Importance: Acts as a federal forum of cooperative federalism, ensuring consensus between Centre and States on indirect taxation. Key in GST rationalization, rate cuts, and reforms like e-way bills and e-invoicing. Source:  THE INDIAN EXPRESS Naegleria fowleri Category: SCIENCE AND TECHNOLOGY Context: A brain-eating amoeba, has caused the death of a child and infected two others in Kerala’s Kozhikode The infection, called primary amoebic meningoencephalitis (PAM), is extremely rare but nearly always fatal, with a global fatality rate of about 97%. The amoeba thrives in warm freshwater such as ponds, lakes, and rivers, and infects people through the nose while swimming—not through drinking water. Symptoms appear within 1–18 days and include headache, fever, nausea, vomiting, altered mental state, and can progress to coma. There is no proven effective treatment, though drug combinations are attempted