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ARTICLES | IIA

Expert astro-photographers and amateur astronomers came together at the Hanle Dark Sky Reserve between 29 September to 4 October 2024, for the second Star Party.

The unique event was organised by the Indian Institute of Astrophysics (IIA) an autonomous institute of the Department of Science and Technology (DST) in collaboration with Department of Wildlife Protection of UT Ladakh, and Bhabha Atomic Research Centre (BARC) and was attended by more than 45 astronomy enthusiasts from across the country. Hanle and the surrounding region are host to some of the darkest night skies in India. Hence, the Hanle Dark Sky Reserve (HDSR), centred around the Indian Astronomical Observatory, was notified by the Govt. of Ladakh in December 2022, and since then, it has been a major attraction for astro-tourism from across the country.

Using 100 years daily records of the Sun at the Kodaikanal Solar Observatory, astronomers have succeeded in mapping, for the very first time, the variation in the rotation speed of the Sun’s chromosphere, from the equator right up to its polar regions. The research can help give a complete picture of the Sun's inner workings.

This paper was published in the Astrophysical Journal, titled “Equator to Pole Solar Chromospheric Differential Rotation Using Ca-K Features Derived from Kodaikanal Data”, and was authored by Kharayat, Hema (Indian Institute of Astrophysics and M.L.K.P.G. College, Balrampur) and Singh, Jagdev, Priyal, Muthu and Ravindra, B. from Indian Institute of Astrophysics.

Evidence of interaction between a radio jet emitted from special kind of galaxies called Active Galactic Nuclei (AGN) and the surrounding interstellar medium at small spatial scale of about 10 parsecs has been detected for the first time in a dwarf galaxy situated at a distance of about 14 million light years. This finding challenges the hypothesis that only large and massive galaxies jets from which regulate star formation, host AGN powered by massive black holes. Combining data from radio to X-ray wavebands from the galaxy NGC 4395, researchers from Indian Institute of Astrophysics (IIA), an autonomous institute of the Department of Science and Technology (DST) observed evidence for such an interaction at the scale of 10 parsecs, or about 30 light years, around the black hole at the centre of this galaxy.

This study was published in a paper in the Astrophysical Journal, titled “Evidence for Low-power Radio Jet–ISM Interaction at 10 pc in the Dwarf AGN Host NGC 4395”, and was authored by Payel Nandi (lead author), C.S. Stalin, and Ram Sagar from IIA, along with other collaborators spread across institutions in Europe and India.

A new way to probe deeper into the Sun’s secrets has been found by studying the magnetic field at different layers of the solar atmosphere using data from the Kodaikanal Tower Tunnel Telescope. A study led by IIA researchers examined an active region (sunspot) with complex features, including multiple umbrae and a penumbra, through simultaneous observations in the Hydrogen-alpha and Calcium II 8662 Å lines from the Kodaikanal Tower Tunnel telescope. It provides a comprehensive analysis of the line-of-sight (LOS) magnetic field through these simultaneous observations. The results indicate that the Hα line core consistently infers weaker magnetic field strengths than the Ca II 8662 Å line inversions, suggesting that the Hα line samples higher atmospheric layers than the Ca II IR triplet.

Press release published here.

Download the paper from here.

Astronomers have discovered a new correlation using 100 years of solar data from the Kodaikanal Solar Observatory, which will help predict the strength of an upcoming solar cycle maximum as well as help in space weather forecasting. The publicly available data from the observatory (which is celebrating 125 years this year) with a span of more than nine solar cycles, each cycle extending for about 11 years, was used to detect the large-sized (30,000 km) convective patterns called supergranulations on the visible surface of the sun. The analysis shows that these supergranular lane widths were positively correlated with the sunspot number.

Press release published here.

Download the paper from here.

Researchers have made a groundbreaking discovery of a vampire star in the star cluster M67 located in the constellation Cancer, that has been rejuvenating its youth by sucking up material from a companion.  The study provides rare insights into the binary star evolution process and provides an important missing link in the rejuvenation in these stars. This discovery experimentally confirms the theoretical prediction that the vampire stars are formed by acquiring polluted matter through transfer from their companion, leaving behind a remnant white dwarf. The rarity of such chemically polluted systems is still a mystery and the team thinks that it may be due to the quick settling of the pollutants in the atmosphere of the vampire stars.

Press release published here.

Download the paper from here.

A new online tool to create a comprehensive star catalogue for the Adaptive Optics (AO) system of the upcoming Thirty Meter Telescope (TMT), can enable this ground-based telescope-- one of the largest to be operational in the next decade, generate sharper astronomical images. Researchers at IIA and their collaborators have developed an automated code that can be used as an online tool to create a catalogue of Near Infrared (NIR) stars. The automated code can compute the expected near-infrared magnitudes of stellar sources identified in various optical sky surveys using their optical magnitudes.

Press release published here.

Download the paper from here.

Intense auroral activity was captured by cameras at our Indian Astronomical Observatory in Hanle and Merak in Ladakh on the night of 10-11 May, caused by intense geomagnetic storms arising from Coronal Mass Ejections from the Sun impacting the Earth. Strong aurorae were predicted to occur, and were indeed seen from across the globe at much lower latitudes than usual.

Photos and videos can be downloaded from here.

The Moon passed in front of the bright red star Antares on 27 April 2024, hiding it for roughly 40 minutes. This event was visible only from southern India. The SCOPE Section of IIA filmed the disappearance and reappearance of Antares and made it publicly available.

Videos of the occultation can be found here.

The 125th anniversary of the iconic Kodaikanal Solar Observatory (KSO) was celebrated on 1 April 2024 by Indian Institute of Astrophysics (IIA), an autonomous institute of the Department of Science and Technology (DST), to remember the history of KSO, felicitate its scientists, and honour its legacy was a milestone for astronomy in India. The KSO houses a digital repository of 1.2 lakh digitised solar images and thousands of other images of the Sun recorded every day since the start of the 20th century. A.S. Kiran Kumar, former Chairman of ISRO and Chairperson of the Governing Council of IIA then unveiled the KSO 125 logo for the anniversary celebrations along with a booklet detailing the history and the research highlights of the Observatory.

Webpage of the event here.