ISRO shares new findings on black hole
During the high-brightness phase, the team discovered that the rapid flickers in X-rays were repeating about 70 times per second, known as Quasi-periodic Oscillations (QPOs). Interestingly, such 'fast' flickers vanish during the low-brightness phase, noted the researchers Anju Nandi from ISRO, Santabrata Das from IIT- Guwahati, Sreehari H from Hafiza University and Seshadri Majumder from IIT Guwahati.
India's first dedicated multi-wavelength space observatory, AstroSat, has been continuously monitoring the black hole GRS 1915+105 since its launch in September 2015 and is working to provide insights into the source's behaviour. The research team stated that they found that these rapid QPOs are intimately connected to a super-heated cloud of energetic plasma surrounding the black hole, known as the corona. During the bright, high-energy phases when QPOs are strongest, the corona becomes more compact and significantly hotter with higher luminosity. Conversely, in the dimmer dip phases, the corona expands and cools, causing the flickers to vanish. This pattern suggests that the compact oscillating corona seems to be the origin of these fast QPO signals.
This research work titled- Evidence of oscillating 'compact' Comptonised corona in GRS 1915+105: insights into HFQPOs with AstroSat- was also published in the journal Monthly Notices of the Royal Astronomical Society, on July 4, 2025. ISRO shared the details on July 25.
The research team noted that these findings will help scientists understand what happens in the vicinity of a black hole, where gravity is incredibly strong and conditions are extreme.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Time of India
17 minutes ago
- Time of India
Unique space radar will track earth's every shake & shift
Built By Isro & Nasa, This Satellite Could Become Our Planet's Early Warning System For Floods, Crop Loss, Coastal Erosion Our planet is constantly changing. The ground shifts, often unnoticed. Glaciers inch forward, coastlines retreat and forests thin or thicken with the seasons. Some of these changes unfold slowly. Others strike without warning. On Wednesday, July 30, a satellite called Nisar (Nasa-Isro Synthetic Aperture Radar ), the first joint satellite mission for the two space agencies, will lift off to track these movements. It will scan the Earth's surface every 12 days, capturing changes as small as a few centimetres. Each pixel will represent an area roughly half the size of a tennis court. The data Nisar will gather will serve a variety of purposes — it will warn of flooding, coastline erosion, guide realtime disaster response, improve food security and even track ships. It will be one of the most advanced Earth-observation satellites ever to go up. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Indonesia: Unsold Sofas Prices May Surprise You (Prices May Surprise You) Sofas | Search Ads Search Now Undo Beaming to villages Nisar's launch also comes 50 years after India and US collaborated on a very different kind of project: the Satellite Instructional Television Experiment, or SITE. Launched a month after then PM Indira Gandhi declared the Emergency, SITE began broadcasting on Aug 1, 1975 to community TV sets in 2,400 villages across Karnataka, Rajasthan, Odisha, Bihar, Madhya Pradesh and Andhra Pradesh. It was seen as a mutually beneficial deal for Nasa and Isro. At the time, 40% of India's population was in villages with fewer than 3,000 people, and a quarter were in hamlets with fewer than 200. Traditional infrastructure alone couldn't reach them, but space tech could. So, an agreement was made: The US would supply its ATS-6 telecommunications satellite for a test run; India would build the ground infrastructure. The experiment was a success. SITE reached around 2 lakh people, helped train 50,000 science teachers in primary schools and beamed advice to thousands of farmers, becoming 'the largest sociological experiment in the world'. Before SITE, India and US had worked together in space for close to a decade, but this was the first time their efforts touched lives. 50 years apart 'It took 50 years from one major joint project in communications and broadcasting to another project on Earth observation,' former Isro deputy director Arup Dasgupta, who led deployment of SITE's receivers, told TOI. He said Nisar's launch showed how much Isro had progressed. 'Fifty years ago, we used a Nasa satellite to beam educational programmes. Today, we are launching their payload along with our own Synthetic Aperture Radar on an Indian launcher.' Nisar has been described by Nasa-JPL project scientist Paul Rosen as 'a storyteller of Earth's changing surface'. The satellite will capture motion of land, ice, water and vegetation across seasons, which means data for seismologists, climatologists, agriculturists, conservationists and many others. And the information will be freely available to them. A dual-band instrument Equipped with dual radar systems — the L-band by Nasa and Sband by Isro — Nisar can see through clouds and observe Earth day or night. It will scan the Himalayas, beaches of California, the Amazon rainforest and the farms of Punjab — not just once, but repeatedly, creating a time series of surface changes that show what has shifted, where and how fast.'It lets us read Earth's surface like a series of moving frames,' Rosen said. 'Using SAR, we can measure ground displacement down to even millimetre precision.' The longer-wavelength L-band penetrates vegetation and interacts with features such as rocks and tree trunks. Shorter S-band captures surface details like leaves and topsoil. Combined, they allow scientists to view the same landscape through two different lenses, revealing structure and change. 'A dual-band SAR like this has never flown before. L-band opens up deeper imaging and new interferometric applications. You can track deformation, subsidence, and seismic shifts in much finer detail,' said professor PG Diwakar of the National Institute of Advanced Studies. One major focus will be the Himalayas. 'We've never had such a tool for studying Himalayan snow, glaciers and lake systems. Nisar will let us observe how glacial lakes evolve — critical for understanding GLOF (glacial lake outburst flood) risk,' Diwakar said. L-band's ability to see below the canopy also improves forest assessments. For farmers, it will help forecast yields and assess crop loss. In disaster-prone areas, Nisar's interferometric accuracy will boost early detection, measuring ground shifts over wide regions. It will even aid during oil spills. 'This will be the first mission between US and India to observe Earth in such a detailed way,' said Nicola Fox, associate administrator, Nasa science mission directorate. Roots in 1978 Nisar's roots go back to a breakthrough launch in 1978, when Nasa put in orbit Seasat — the world's first satellite with SAR. The mission lasted only 105 days, but the data this satellite produced reshaped Earth observation. Now, nearly 50 years after Seasat, Nisar is set to go up and stay there for at least three years, generating more data daily than any other previous remote-sensing satellite. For India, which will handle its launch, the satellite deepens its scientific engagement with the world. For Nasa, it extends an Earth observation legacy. Together, they have created something greater than the sum of their parts — a satellite that watches Earth not as a snapshot, but as a breathing, evolving whole.
Time of India
4 hours ago
- Time of India
India growing by leaps and bounds in space sector: PM Modi
NEW DELHI: Ahead of the National Space Day, PM Narendra Modi on Sunday highlighted India's growing capabilities in the space sector, citing Group Captain Shubhanshu Shukla's recent journey to International Space Station (ISS) and the emergence of more than 200 startups in the sector. Talking about Shukla, who was one of the four crew members of the Axiom-4 mission to ISS, Modi, in his 124th 'Mann Ki Baat' episode, said that when the astronaut landed back on Earth, a "wave of happiness rippled through every heart" and the "whole country was filled with pride". He also highlighted that the success of Isro 's Chandrayaan-3 mission had created an atmosphere of curiosity in the country for space endeavours. "I remember, when Chandrayaan-3 successfully landed in Aug 2023, a new ambience was created in the country. A new curiosity also arose among children about science, about space. Little children now say, we will also go to space; we will also land on the Moon - we will become space scientists," the Prime Minister said. He specially mentioned the 'INSPIRE-MANAK Abhiyan', which promotes innovation among children by providing them with a platform to develop innovative ideas rooted in science. "Under this, five children are selected from each school. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like If you have a mouse, play this game for 1 minute Navy Quest Undo Each child comes up with a new idea. So far, lakhs of children have joined, and since Chandrayaan-3, their number has doubled". On India's space startups, Modi pointed out that their number has quadrupled in the last five years. "Five years ago, there were fewer than 50 startups. Today, there are more than 200." As regards the upcoming National Space Day on Aug 23, he said, "How will you celebrate it..., do you have any new ideas? Do send me a message on the NaMo App". He also mentioned the recent achievements of students in science and mathematics, giving a shout-out to the country's brightest minds.
Hindustan Times
5 hours ago
- Hindustan Times
‘One mission to watch Earth': ISRO-NASA's joint satellite NISAR set for July 30 launch
The Indian Space Research Organisation (ISRO) on Sunday stated that the upcoming launch of NISAR, the first joint Earth observation satellite by ISRO and NASA, will mark a key milestone in Earth observation technology. The NISAR mission's primary objectives are to study land & ice deformation, land ecosystems, and oceanic regions in areas of common interest to the US and Indian science communities.(X/@isro) NISAR will be launched from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh, on July 30 at 17:40 IST. NISAR is the first mission of its kind, jointly developed by ISRO and NASA. It is an L- and S-band, global, microwave imaging mission, with the capability to acquire fully polarimetric and interferometric data, as per an official statement from ISRO. The unique dual-band Synthetic Aperture Radar of NISAR employs the advanced, novel SweepSAR technique, which provides high-resolution and large-swath imagery. NISAR will image the global land and ice-covered surfaces, including islands, sea-ice and selected oceans, every 12 days. The NISAR mission's primary objectives are to study land & ice deformation, land ecosystems, and oceanic regions in areas of common interest to the US and Indian science communities. Also read: Modi hails Shubhanshu Shukla's return to Earth as India's new Chandrayaan moment The joint mission will accomplish multiple tasks, including measuring the woody biomass and its changes, tracking changes in the extent of active crops, understanding the changes in wetlands' extent, and mapping Greenland & Antarctica's ice sheets and the dynamics of sea ice and mountain glaciers. As per the statement, it will also help characterise land surface deformation related to seismicity, volcanism, landslides, and subsidence & uplift associated with changes in subsurface aquifers, hydrocarbon reservoirs, etc. "One mission to watch Earth. #ISRO #NASA builds, Earth benefits. This marks a key milestone in Earth observation technology. Stay tuned as we bring you closer to the mission that watches our world," ISRO sais in a post on X. "The Spacecraft is built around ISRO's I-3K Structure. It carries two major Payloads viz., L & S- Band Synthetic Aperture Radar (SAR). The S-band Radar system, data handling & high-speed downlink system, the spacecraft and the launch system are developed by ISRO. The L-band Radar system, the high-speed downlink system, the Solid-State Recorder, the GPS receiver, and the 9 m Boom hoisting the 12m reflector are delivered by NASA. Further, ISRO takes care of the satellite commanding and operations; NASA will provide the orbit manoeuvre plan and RADAR operations plan. NISAR mission will be aided with ground station support from both ISRO and NASA for downloading of the acquired images, which, after the necessary processing, will be disseminated to the user community," the statement added. The data acquired through S-band and L-band SAR from a single platform will help scientists understand the changes happening to Planet Earth. The complex payloads and mainframe systems have been designed, developed, qualified and realised over a period of 8 to 10 years. "The S- Band SAR and L- Band SAR were independently developed, integrated and tested at ISRO and JPL/NASA respectively. The Integrated Radar Instrument Structure (IRIS), consisting of S - Band and L - Band SAR and other payload elements were intergrated and tested at JPL/NASA and delivered to ISRO," it stated. Mainframe satellite elements and payloads were assembled, integrated and tested at URSC/ISRO. The mission phases can be broadly classified into: Launch phase, Deployment Phase, Commissioning Phase and Science Phase. NISAR will be launched onboard the GSLV-F16 launch vehicle on July 30, 2025 from ISRO's Satish Dhawan Space Centre (SDSC), also referred to as Sriharikota High Altitude Range (SHAR), located in Sriharikota on the southeast coast of the Indian peninsula. It hosts a 12m dia large reflector which shall be deployed in-orbit 9m away from the satellite by a complex multistage deployable boom designed and developed by JPL/NASA. The first 90 days after launch will be dedicated to commissioning, or In-Orbit Checkout (IOC), the objective of which is to prepare the observatory for science operations. Commissioning is divided into sub-phases of initial checks and calibrations of mainframe elements followed by JPL engineering payload and instrument checkout. The science operations phase begins at the end of commissioning and extends till end of mission life. During this phase, the science orbit will be maintained via regular maneuvers, scheduled to avoid or minimize conflicts with science observations. Extensive calibration and validation (CalVal) activities will take place. The observation plan for both L and S-band instruments, along with engineering activities (e.g., maneuvers, parameter updates, etc.), will be generated pre-launch via frequent coordination between JPL and ISRO, the statement added.
