Which limit describes the brightness at which radiation pressure pushing matter outward balances gravity pulling it inward?
- A.Chandrasekhar limit
- B.Eddington limit
- C.Roche limit
- D.Schwarzschild radius
Correct answer
Explanation
The correct answer is the Eddington limit. It is often used as a benchmark for how bright an accreting object can be, since beyond it the outward push of radiation would overwhelm the inward pull of gravity. Ultraluminous X-ray sources are puzzling precisely because they appear to shine more brightly than this simple balance predicts, and the new work concludes that ULX-8 is powered by a black hole accreting at rates exceeding this classical ceiling. Option A is wrong because the Chandrasekhar limit concerns the maximum mass of a stable white dwarf rather than a brightness ceiling. Option C is wrong because the Roche limit is the distance within which a body is torn apart by tidal forces. Option D is wrong because the Schwarzschild radius marks the event horizon of a non-rotating black hole, a size and not a luminosity.
Read the full article: IIA Team Traces Black Hole Behind Bright X-ray Source ULX-8
Practice Questions
Over roughly how long a period were the X-ray observations of NGC 4490 ULX-8 tracked in the new study?
- A.6 years
- B.12 years
- C.24 years
- D.40 years
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Archival and recent observations of the source were drawn from the Chandra, XMM-Newton and Swift space-based X-ray telescopes covering the years 2000 to 2024, which makes it one of the longest X-ray studies of this object carried out so far.
Read the full explanation →The research team that explained the behaviour of ULX-8 was drawn mainly from which institutes?
- A.Indian Institute of Astrophysics and Raman Research Institute
- B.Physical Research Laboratory and Space Applications Centre
- C.Tata Institute of Fundamental Research and Indian Institute of Science
- D.National Centre for Radio Astrophysics and Aryabhatta Research Institute
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The paper was authored by Tarang Vashisht, a student at IISER Mohali, together with Aru Beri of the Indian Institute of Astrophysics and researchers from IUCAA and the Raman Research Institute.
Read the full explanation →Which of these is India's proposed next-generation timing and spectroscopy mission named in the announcement?
- A.AstroSat
- B.NewAthena
- C.XSat
- D.Aditya
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The announcement describes it as India's proposed next-generation timing and spectroscopy mission, which together with other future observatories will bring improved sensitivity and monitoring capability for studying ultraluminous X-ray sources.
Read the full explanation →How many beneficiaries have the weather forecast and agromet advisory services reached in the region?
- A.1,467
- B.3,540
- C.5,467
- D.9,675
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The minister said forecasts are now disseminated at the panchayat level across all panchayats in the five districts, and that the weather forecast and agromet advisory services have reached this many people, giving farmers and residents wider access to weather information.
Read the full explanation →How many Automatic Weather Stations does the region now have, against three earlier at Udhampur, Kathua and Ramban?
- A.8
- B.10
- C.12
- D.15
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Nine stations were added to the three that existed at Udhampur, Kathua and Ramban, taking the total to twelve; of the new ones, four are in Kishtwar, two each in Doda and Ramban, and one in Kathua.
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