CosmicVarta
Platform for promoting Indian astronomy research to the public.
Category General
The Indian Space Research Organisation (ISRO) commenced the new year with the launch of the X-Ray Polarimeter Satellite (XPoSat). X-ray polarization measurement is an emerging technique in X-ray astronomy and holds immense potential for enhancing our understanding of the extreme...
The Sun has fascinated mankind since the dawn of civilization. From famines to fertile farms, every aspect of life on Earth was defined by it. Unaware of the true nature of the Sun, humans have worshipped this mighty celestial being...
India’s ambitious space program reaches new heights as Chandrayaan-3, the eagerly anticipated lunar exploration mission, prepares for launch. Get ready to witness history in the making as India embarks again on an extraordinary journey towards the Moon, marking a remarkable...
The Cosmology Education and Research Training Centre (COSMOS) is an upcoming state-of-the-art planetarium, along with a data training centre and resource centre in Mysuru. The Indian Institute of Astrophysics (IIA) has formed an Education and Public Outreach Committee (EPOC) for...
‘Frontiers in Cosmology’ was a five-day international conference held at Raman Research Institute (RRI) during February 20 – 24, 2023. More than 100 participants including researchers, scientists, students and faculties from around the world attended the meet.
The Department of Physics and Electronics at CHRIST (Deemed to be University) in Bangalore, Karnataka, organised the National Seminar on Advances in Astrophysics and Space Science Research (NSAASSR) from February 13 to 15, 2023. The seminar was organised as part...
CosmicVarta celebrates its first birthday today! Hurray!
It was a wonderful year indeed.
Today, we take a look back at our journey and briefly talk about our future plans.
As part of the National Science day celebrations, the Indian Institute of Astrophysics organised a panel discussion titled- Bengaluru The Astronomy City. The focus of the meeting was to educate the young students regarding various opportunities in astronomy and astrophysics...
A significant fraction of the advances in science and technology arises due to seminal contributions by women - all the while tackling a series of battles against social norms and skewed opportunities. Even today, there exists a lack of representation...
Being involved in research means dealing with a lot of papers on a day to day basis. Be it reading them, organizing them, or referencing them we often face a perilous task. A collection of scores of pdf documents scattered...
Progress is possible only when everyone capable of contributing is given an equal chance irrespective of gender, community and nationality. While there is a long way to go before this gap is fulfilled, it should be noted that we as...
A popular article exploring how the ages of the Earth and Moon were measured.
GitHub has become the go-to tool for software engineers across the world to keep their codes together and collaborate with each other. Being easy, seamless, and available on all the platforms makes it a brilliant choice indeed.
A popular article exploring how the age of the Universe was calculated.
Prof. Thanu Padmanabhan, one of the stalwarts of theoretical physics, and a shining star of the Indian scientific community, left his mortal abode on the 17th of September this year. With a stellar career spanning over four decades, he has...
CosmicVarta is a team effort where we all come together to discuss astronomy and related tools and ideas. Come join us on this journey!
Category Solar and Stellar Astrophysics
This article explains the importance of the Sun’s coronal magnetic field. In view of this, this article elaborates the capability of spectral lines emitted in the extreme-ultraviolet and delineates the promising technique of the Hanle effect in deriving the coronal...
Ionospheric irregularity studies are important aspects for understanding ionospheric physics and related processes, especially near the low-latitude regions. This work, for the first time, shows the nature of the ionospheric irregularities present during these observation days and sets a path...
This article is about investigating the characteristics of Interplanetary Coronal Mass Ejections using in-situ observation. ICMEs are well-known to expand as they propagate through the heliosphere. Despite this, their cross-sections are usually modeled as static plasma columns within the magnetohydrodynamics...
Forecasting the strength of the solar cycle is of the utmost importance because it affects space weather and our technology-based society. By a riveting feature of the solar cycles, i.e. Waldmeier effect (WE2), we find a linear relationship between the...
The article discusses the structure of the neutron star crust. In the neutron star’s crust, exotic structures commonly known as “nuclear pasta” are believed to exist. The pasta structure impacts various structural, thermal and transport properties of the crust and...
As the saying goes, “न कंचित् शाश्वतम्” (lit. Nothing is permanent), and hence the nature of this universe. The ever-evolving twinkles in the starry night are also non-discriminate towards this concept. If a star is born, it ought to die....
With the gravitational wave observations capturing the coalescence of compact objects, hunting for black holes has taken quite a front-row seat in astronomical observations. Here, we discuss two such detection of black holes in orbit with a main sequence companion,...
During astronomical observation, astronomers measure the amount of energy emitted by astronomical objects. This energy is generally measured in terms of the flux density of the source. At radio frequencies, these measurements are calibrated using calibrator sources, which have known...
The Great Dimming of Betelgeuse (alpha Orionis) in late 2019 puzzled astronomers across the globe. The star appeared the faintest in all its modern recorded history. The mystery mounted as it quickly regained brightness in the next few months, and...
This article is based on the paper published in the Journal of Astrophysics & Astronomy. The article shows the results of our deep optical photometric observations of a young cluster NGC 1893 taken with the 3.6m Devasthal Optical Telescope. Based...
In this article, we presented the temporal evolution of elemental abundances during solar flares of GOES B1−B4 class, the weakest events for which such studies have been possible so far, using observations with XSM on board Chandrayaan-2. This study was...
Light when seen correctly provides rich information on what happens in the cosmos. In this article, we showcase our work on identifying signatures of the solar wind in the solar chromosphere – far lower in the solar atmosphere than what...
XSM onboard Chandrayaan-2 observed the Sun during the deepest solar minimum of the past century from in 2019-2020. By studying the XSM spectra for the days when the Sun was very quiet, researchers have found that the abundances of all...
We present a catalog of 3339 hot emission-line stars (ELS) identified from 451,695 O, B, and A type spectra, provided by the LAMOST DR5 release. We developed an automated python routine that identified 5437 spectra having a peak between 6561...
This article takes the reader through a journey of inferring the cosmos - specifically our dear neighbour Sun - through various properties of light. The journey meanders through our work on understanding solar chromospheric properties through spectral lines, and seems...
Starting from the history of star classification in the millinniums, this interesting note will take you through some of the very basic concepts on emission-line stars. You will be able to understand what they are and why these type of...
This article traces the origins of the coronal heating problem, and describes in vivid detail our efforts in resolving this through machine learning. This is a non-technical article based on our paper, but references have been appended for the interested...
XSM onboard Chandrayaan 2 observed the Sun during its minimum activity period in 2019-2020. Using this data, the researchers have for the first time detected a very large number of small scale explosions, called microflares, happening on the Sun. The...
A general article exploring some of the most extreme stars of the universe. Each one of them deserves the word ‘most’ for varied reasons. Just read and enjoy the mysterious cosmos sitting at home.
Pre-main-sequence (PMS) stars evolve into the main-sequence (MS) phase over a period of time. Interestingly, we found a scarcity of studies in the existing literature that examine and attempt to better understand the stars in the PMS to MS transition...
It is well known that the Sun rotates differentially, i.e. its equator rotates faster than the pole. Not only at the surface, but the solar rotation profile also varies with the radius, which was discovered in helioseismic observation. This observation...
Curiosity is what has driven mankind to observations of new phenomena. Every twinkling star in the night sky is definitely not due to the atmospheric refraction of earth. Rather, one might be looking at a variable star, each with a...
The focus of this article is solar wind. I first take the reader through the theory & observations, and various properties of solar wind. Then, I take a detour through machine and deep learning which form the basis of our...
Category Earth and Planetary Astrophysics
Ionospheric irregularity studies are important aspects for understanding ionospheric physics and related processes, especially near the low-latitude regions. This work, for the first time, shows the nature of the ionospheric irregularities present during these observation days and sets a path...
On account of International Moon Day, we present a brief overview of the formation scenarios of the Moon. We also discuss the findings of Chandrayaan.
Polarization is an emerging technique in the field of exoplanets. Understanding the basic physics behind the polarization of the light observed from the planets can help us study them in detail. One such aspect is to study the polarization of...
Category Instrumentation and Methods for Astrophysics
One of the science goals of the Aditya L1 is to map the coronal magnetic field topology. The infrared channel of the VELC payload of the Aditya L1 is equipped with a spectropolarimeter to perform full stokes spectropolarimetric observations in...
This article is the review of a journal paper on the Visible Emission Line Coronagraph, the primary payload onboard India’s first solar space mission, ADITYA-L1. The paper discusses some technical details of VELC and the work done in analyzing them....
Category High Energy Astrophysical Phenomena
The process of production of high energy gamma-ray photons within the jets of blazars remains a mystery, with limited understanding of processes driving the particle accelerations over parsec scales and beyond. The complexity deepens with the detection of photons reaching...
The neutron star is the most well known compact object in the Universe. It has several macroscopic properties such as mass (M), radius (R), compactness (C), tidal deformability (Λ), and moment of inertia (I), which can be observed using different...
Blazars are a rare class of active galactic nuclei (AGN), in which the jets are pointed directly toward our line of sight, making them one of the brightest yet extremely compact sources. Relativistic effects such as beaming makes the jet...
Dying heavy stars forms black holes and sometimes emit jets, producing very narrow-angle flashes of gamma rays known as Gamma-Ray Bursts (GRBs). This article summarises the findings from the follow-up of such a GRB 210204A. The GRB showed typical afterglow...
An active galactic nucleus (AGN) is powered by the matter accreting onto the central supermassive black hole (SMBH) at the centre of a galaxy. Changing look (CL) AGNs are those sources that show rapid change in the column density of...
General theory of relativity proposed by Albert Einstein in 1915 has passed all the experimental and observational tests with flying colors. Gravitational waves from the merger of compact binaries such as black holes and neutron stars provide a unique opportunity...
Hydrodynamic flows around black holes is a fascinating area of research that provides a window into the processes that power relativistic jets and energetic particle acceleration. However, this is a challenging task when studied using the full general relativistic framework....
As the saying goes, “न कंचित् शाश्वतम्” (lit. Nothing is permanent), and hence the nature of this universe. The ever-evolving twinkles in the starry night are also non-discriminate towards this concept. If a star is born, it ought to die....
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (greater than two seconds) duration are produced by the core-collapse of massive stars, and those of short (less than two seconds) duration by the...
With the gravitational wave observations capturing the coalescence of compact objects, hunting for black holes has taken quite a front-row seat in astronomical observations. Here, we discuss two such detection of black holes in orbit with a main sequence companion,...
Long after humans figured out that the small bright dots in the night sky were just another sun-like object, and not very long after the discovery of the neutron, in the year 1933, Baade and Zwicky theorized the existence of...
Supernovae are extreme astrophysical transient phenomena marking the death of stars. In this article, I take you to the journey of the life of a star as massive as 100 times our sun. Through the state-of-the-art simulation tool MESA, we...
India has a long history of more than two decades of observations of optical counterparts of gamma-ray bursts (GRBs) using Indian meter-class telescopes like the 1.04m Sampurnanand Telescope (ST), 1.3m Devasthal Fast Optical Telescope (DFOT), 2m Himalayan Chandra Telescope (HCT),...
Observed pulsars are misaligned in nature. The misalignment scenario occurs when the rotation axis and the magnetic axis of the star forms a finite non-zero angle between them. This scenario gives rise to very interesting phenomenons. This article explores such...
Yash Bhargava from Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, takes us through the journey of the death of a star in this wonderful article about his work.
Researchers from Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, present the new measurements of the spin and orbital parameters of the binary star system ‘Cen X-3’. This work is a step forward in understanding the complex dynamics of the...
Estimating the strength of the magnetic field of a neutron star in a binary star system ‘Cen X-3’
Gravitational waves are invisible ripples in space travel at the speed of light. It is generated in different scenarios, such as when two celestial bodies orbit around each other, an isolated body with tri-axial symmetry spins, inhomogeneity in matter distribution...
Category Astrophysics of Galaxies
Embark on a cosmic journey as Gourab Giri explores the enigmatic X-shaped structures observed in radio galaxies, formed by the ejection of jets from supermassive black holes.
Space vehicles are propelled by rocket engines that generate thrust by expelling exhaust at extremely rapid speeds. As Newton’s third law states “For every action, there is an equal and opposite reaction”, the engines help to accelerate the rockets forward...
Initially, early-type galaxies were considered aged, evolved systems with a reddish appearance, primarily comprising older stars and lacking young star formation due to limited gas and dust resources. However, contemporary techniques, such as integral field spectroscopy for studying star motion...
Blazars are a rare class of active galactic nuclei (AGN), in which the jets are pointed directly toward our line of sight, making them one of the brightest yet extremely compact sources. Relativistic effects such as beaming makes the jet...
This article discusses the results from our combined radio polarization and emission line study of five type-2 radio-quiet quasars. We investigate the origin of radio emission in these sources and understand what impact the local gaseous environments have on the...
An active galactic nucleus (AGN) is powered by the matter accreting onto the central supermassive black hole (SMBH) at the centre of a galaxy. Changing look (CL) AGNs are those sources that show rapid change in the column density of...
The interstellar molecular clouds are the high-density regions between the stars having elements in the molecular phase. These clouds usually come up with different structures based on the influence of nearby massive ionizing stars. Also, these stars can either hinder...
Dust is as ubiquitous in galaxies as are stars, gases and dark matter. Although dust forms less than 1% of the mass of the interstellar medium, its importance can be gauged from the fact that dust reprocesses more than half...
The interaction of radio jets with gas associated with the host galaxy could play an important role in determining their morphology. Such interactions may be more prevalent at high redshifts, when these powerful AGN are still the assembly sites of...
AGNs are very luminous objects at the centre of active galaxies. The inner regions of these galaxies can not be resolved directly, yet the understanding of these regions can be achieved by employing indirect methods. In this study, we employed...
There is a lack of consensus on the origin of radio emission in radio-quiet (RQ) and radio-intermediate (RI) AGN. Primary contenders include low-power radio jets, winds, star-formation and coronal emission. Our multi-frequency, multi-scale radio polarization study has revealed a multi-component...
Galaxies are the building blocks of our universe. A comprehensive theory of how galaxies evolve with cosmic time is key to understanding how the universe turns out the way it is today. Decades of observational, theoretical and computational efforts have...
A small percentage of the ejected hot plasma flows (the jets) from supermassive blackholes are observed to deviate from their intended path, resulting in unusual jetted morphologies. One of these peculiarities appears when the jet starts to dance /precess around...
Stars take birth in molecular clouds. The presence of magnetic fields everywhere in the universe naturally creates a curiosity to investigate their role at all the stages of star fomation. The motion of clouds through the interstellar medium in the...
When observed with a radio telescope, a giant peculiar X-shaped morphology is seen in some galaxies. It is difficult to understand what gives rise to such peculiar morphology; And, to date, this is a topic of debate among astronomers themselves....
The study of the cosmos is only complete when we can receive and analyse data from the entire electromagnetic spectrum, ranging from picometer-sized gamma rays to several meters long radio waves. This realization is what led to the advent of...
Most of the massive galaxies in the Universe host a supermassive black hole (SMBH) at their center. A minority among them are known as active galaxies and host active galactic nuclei (AGNs). These AGN are believed to be powered by...
Galaxies reside in the deep potential of invisible matter called dark matter. Their dynamics is significantly affected by the distribution of dark matter around them. Distribution of dark matter around galaxies is usually known as dark matter halo. Most of...
Category Cosmology and Nongalactic Astrophysics
Studying the spatial distribution of extragalactic source populations is vital in understanding the matter distribution in the Universe, the cosmological evolution of matter density fields and the relationship between dark matter and luminous matter. This article investigates the clustering properties...
We study how galaxies and other sources in the early universe change the neutral universe or InterGalactic Medium (IGM) into the ionized one. We compare different kinds of source models and how they ionize the neutral universe which mainly consists...
Space is quite inhomogeneous at small scales. These inhomogeneities may play a significant role in governing the physical phenomena at this scale. Here we have analysed the impact of these inhomogeneities on the Gravitational Wave (GW) observables. For this analysis...
SARAS 3 experiment, designed and developed at Raman Research Institute, has conclusively refuted the claim of detection of the signal from cosmic dawn by EDGES experiment. It has become the first experiment worldwide to reach the required sensitivity and cross-verify...
Fast Radio Bursts are millisecond-duration radio transients of extragalactic origin. Their dispersion measures are sensitive to the presence of ionized matter along their lines of sight. This unique measurable makes FRBs a promising cosmological probe that can shed light on...
Category Astrobiology
The only life forms we know about are the ones that exist on Earth. Due to advancements in space exploration, it has become possible to send rovers, probes, space crafts, and telescopes in further deep space. With the help of...
Category Featured
We Indians celebrate National Science Day on 28th February each year to mark the discovery of the Raman effect by Sir C. V. Raman. Some of Raman’s discoveries like the Raman effect (for which he was awarded the Nobel prize),...
Category General articles (in any of the above categories)
A popular article describing the history and contributions of the Vainu Bappu Observatory: the telescope town of India.
My affair with the observatory is also highlighted in brief.
Category Science Outreach
A summary of science outreach performed during the Young Astronomer’s Meeting, 2022.
Category Radio survey
This article describes a series of scientific endeavors undertaken that led to the compilation and characterization of nearly half a million radio sources observed as part of the MeerKAT Absorption Line Survey (MALS, P.I.- Prof. Neeraj Gupta). Remarkably, many of...
Category AGN
This article describes a series of scientific endeavors undertaken that led to the compilation and characterization of nearly half a million radio sources observed as part of the MeerKAT Absorption Line Survey (MALS, P.I.- Prof. Neeraj Gupta). Remarkably, many of...
