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100 Years with Our Closest Star, the Sun

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100 Years with Our Closest Star, the Sun 100 years with our closest star, the sun Shubashree Desikan CHENNAI, MAY 06, 2017 18:55 IST Layered structure The three datasets reveal different layers of the sun. (From left) The H-alpha reveals the filaments; the Ca-K, the chromosphere; the white light images, the photosphere and sunspots. Indian Institute of Astrophysics releases digitised images of the sun for researchers and science enthusiasts Every day, since 1904, staff at the Kodaikanal Solar Observatory in Tamil Nadu have aimed their telescope at the sun, freezing the images of its disc. This data, spanning a hundred years and more, has now been digitised by astrophysicists from the Indian Institute of Astrophysics, Bengaluru, and made available to the public. Apart from use in academic studies of long term behaviour of the sun, the data can be used to better understand sunspot activity which impacts climate and affects telecommunication systems. It also throws light on major events in the past which had an impact on the earth’s magnetic field. “From that knowledge we may understand the current and future events with greater precision. This also allows us to predict future [sunspot] activity levels with better accuracy,” says Dipankar Banerjee, IIAP, the Principal Investigator. While ‘spectroheliograms’ were taken at the Kodai observatory since 1902, it was in 1909 that the data was used to discover the Evershed effect – that gases in the sunspots flowed radially outwards. The discovery by John Evershed put the KSO at par with the best observatories in the world. But its importance eventually declined as it was not upgraded or maintained. In a backhanded way, though, this turned out to be beneficial, because “the pictures had all been taken with the same instrument over the years, and this made it much easier to calibrate and digitise,” says Sudip Mandal, a Ph.D student who has worked on the project. The data is unique not only in that it spans a hundred years, but that there are three sets of images, taken using different filters – White light, H-alpha and Calcium-K. It is known that the sun has a layered structure, and each of these data sets exposes a different layer. Under white light filtering, the sun’s photosphere and the sunspots are visible, while the Calcium-K light can show layers some 2,000 km above this, in the chromosphere. The H-alpha images show up layers a little above the Calcium-K images. Features called “filaments” which are related to large expulsions of material from the sun’s surface can be viewed in the sets. Opening up the digitised data has attracted international attention: Max Planck Institute, Gottingen; National Astronomical Observatories of China, Beijing and Big Bear Solar Observatory, US are interested in studying the way the sun’s luminosity changes. Though the sun appears to have a steady brightness, its luminosity actually undergoes changes over time. Some of the groups. The Big Bear Solar Observatory and the Beijing teams are interested in the H-alpha data in order to study the filaments that can be observed in those shots. Within India, groups from IUCAA, Pune; Physical Research Laboratory, Ahmedabad; and IISER, Kolkata, want to make studies. A movie that the scientists made out of a sequence of hundreds of white light images shows how the sunspots appear and disappear periodically over an eleven-year cycle. Such movies offer immense possibilities for developing educational software, as classes of students can visually experience how the sun and the sunspots behave over the years. Just like CERN offers its data to science hobbyists, for analysis that does not require much training and yet cannot be carried out without human intervention, this data, too, could be used by science fora in India to build citizen science projects. The data was historically archived in photographic plates and film. After the digitisation, the images are preserved in high-resolution digital format. “We store it in FITS [flexible image transport system] which is the most commonly used digital file format,” clarifies Dr Banerjee. Digitising this has been a challenging task wthat involves not just reading and displaying the image but also extracting information – for instance differentiating a sunspot from artefacts such as a scratch or a fungal streak. “It can only be done using a lot of sophisticated mathematical tools. Some are available some we have had to develop to handle these challenges,” says Dr Banerjee. This data can be freely downloaded from https://kso.iiap.res.in and wis also available on request through the contact details given on this website. The project which was initiated about six years ago by S.S. Hasan, then the director of IIAP, has succeeded in converting to digitised format some sixty- seventy thousand images previously stored in photographic plates. The team includes scientists and the big team of research assistants at the Kodaikanal lab. At the moment, the group has released the “lowest level” or raw data and plans are on to eventually release the processed ones, too. https://www.thehindu.com/sci-tech/science/100-years-with-our-closest-star-the- sun/article18400934.ece Assam keelback spotted for the first time in 129 years Shubashree Desikan JULY 11, 2020 20:05 IST Elusive vertebrate: The female snake was spotted in a muddy stream in the Poba reserve forest | Photo Credit: Abhijit Das The team also recorded 400 plants, 270 butterflies, 25 amphibians and 44 reptiles, 239 birds and at least 20 mammals The Assam keelback snake has been sighted by a team from the Wildlife Institute of India, Dehradun, for the first time since 1869. This snake was spotted in 2018 by zoologist Abhijit Das when he, along with a team, was retracing the Abor expedition – an iconic expedition that took place from 1911-1912 that had yielded a rich list of flora and fauna of the Assam region. After due identification, the find has been described in a paper published recently in the journal Vertebrate Zoology. Rewarding expedition The Abor expedition had covered a 130 km stretch along the Siang river from the base camp at Kobo Chapori (elevation approximately 121 metres above sea level) to the head quarter at Yembung ( about 3,500 metres above sea level) and beyond. “The staggering zoological result includes description of 244 species and 14 genera new to science,” says Dr Das. In the latest expedition which traced out the route of the earlier one, too, the researchers were not disappointed. As Dr. Das recounts, “We recorded 400 plants, 270 butterflies, 66 odonates, 25 amphibians and 44 reptiles, 239 birds and at least 20 mammals.” The survey started from Poba reserved forest located at the interstate border of Assam and Arunachal Pradesh on September 30, 2018. “I spotted the snake as I was following a small muddy stream deep inside evergreen forest,” says Dr. Das. “Generally, in a forest you have a forest floor with leaf-litter, but here was a special habitat, consisting of stream and swamp within the forest, which attracted me.” Unlike other snakes, this one took shelter under water, below the fallen leaf-litter, a very special way to avoid attention. Preserved specimens First known as Hebius pealii this snake was named after Edward Peal, a British tea planter who first collected two specimens of this snake from upper Assam, 129 years ago. Of the two collected specimens, one was preserved in the Zoological Survey of India, Kolkata, and the other was kept in the Natural History Museum in London. Since the former specimen had disintegrated, the team had to compare the present specimen they found with the one kept in the Natural History Museum, London. Had that specimen gone bad, making the identification would have been that much more difficult. The Assam keelback is so far known only to inhabit Sivasagar in Upper Assam and Poba in Assam-Arunachal border. So, as far as present knowledge goes, it is an endemic snake of Upper Assam. Through a molecular study, the team has shown that this snake belongs to the genus Herpetoreas, which has only three other known members, and not Hebius. This is also the first description of a live snake and its colouration. This is the first female Assam keelback to have been found. “So, we now know how male and female may differ in morphological characters,” says Dr Das. https://www.thehindu.com/sci-tech/science/assam-keelback-spotted-for-the-first-time-in-129- years/article32052652.ece ‘A Fragmented Feminism: The Life and Letters of Anandibai Joshee’ review: A voice all her own Shubashree Desikan JULY 04, 2020 16:55 IST A life in letters of Anandibai Joshee, who struggled against all odds to become the first trained woman doctor from India and achieved much in a short span On March 31, 1865, in Pune, a girl child was born to Gangabai and Ganpatrao Joshi — their fifth child, whom they named Yamuna. On her ninth birthday, March 31, 1874, she was married to Gopalrao Joshee, a widower of about 26, employed as a postmaster at Thane. She was from then known as Anandibai — a name chosen for her by her husband Gopalrao. In her short life of just 22 years, she made history by becoming the first Indian woman to be trained as a medical doctor, at the Women’s Medical College of Pennsylvania, in Philadelphia. Consumed by tuberculosis, she died in 1887, soon after her return to India with an MD degree in medicine (1886). She had accepted an offer to take charge of the Edward Albert Memorial Hospital in Kolhapur, which unfortunately never materialised. In many ways, her life was similar to that of Srinivasa Ramanujan (1887 -1920) who shook the world of mathematics, but died young of tuberculosis aggravated by malnourishment and lack of care.
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