Category General

XpoSat: India's venture into the new frontier of X-ray astronomy

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...


Aditya-L1: India's Array of Instruments on a Journey Closer to the Sun, Continuing a Legacy of Space Excellence

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...


Chandrayaan-3 : A 14 day lunar cruise

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...


'Where’s the Shadow?' - A workshop in preparation for Zero Shadow Day

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...


India’s expanding Cosmology community

‘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.


Proceedings of the National Seminar on Advances in Astrophysics and Space Science Research (NSAAASSR) 2023

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...


One year of CosmicVarta

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.


Bengaluru: The Astronomy City

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 list of scholarships for women in Science

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...


Mendeley Reference Manager

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...


Voices of the Women in Science - A list of books on women scientists

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...


Measuring the ages of the Earth and Moon

A popular article exploring how the ages of the Earth and Moon were measured.


Using GitHub for Academic Research

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.


Measuring the age of the Universe: An overview

A popular article exploring how the age of the Universe was calculated.


The scientific legacy of Thanu Padmanabhan

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...


What is CosmicVarta?

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

Revealing the mysteries of the Sun's coronal Magnetic Field using high energy spectropolarimetry

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...


Utilization of Navigation with Indian Constellation (NavIC) for space weather and upper atmospheric studies

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...


Investigating the massive plasma blobs from the Sun using an ‘in-situ’ eye

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...


Solar cycle 25 is going to be a bit stronger than cycle 24!

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...


Nuclear Pasta in the crust of neutron star

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...


Astrophysical autopsy of a cosmic demise

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....


Fantastic beasts and where to find them: the elusive nature of X-ray quiet black holes

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,...


Precise Measurement of Flux Density of Radio Emissions from the Sun using Day-time Celestial Radio Sources

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: A Stellar Tipping Point?

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...


How do astronomers understand the evolution of young stars in star clusters?

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...


Evolution of plasma parameters during B class flares

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...


Anyway the plasma moves - it does really matter!

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...


How much Metal does the Quiet Sun Corona contain?

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...


Identifying emission-line stars from a large spectroscopic database

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...


Understanding the solar chromosphere through spectral lines

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...


Classical Ae stars: What are they? Why study them?

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...


Using machine learning to infer Solar coronal heating

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...


Deciphering The Mysteries of The Quiet Sun Explosions

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...


Most Extreme Stars

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.


Identification of a new category of stars: stars in rare transition phase found

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...


The First Theoretical Model of the Near-Surface Shear Layer of the Sun

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...


Twinkle twinkle little stars, should I wonder what you are? A brief account of variable stars

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...


From Sun to Earth using Artificial Intelligence

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

Utilization of Navigation with Indian Constellation (NavIC) for space weather and upper atmospheric studies

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...


The International Moon Day

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 of the light reflected from exoplanets: A new window into the study of exoplanets

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

Magnetic Field Measurements of the Solar Corona by Aditya L1

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...


Technical aspects of VELC onboard ADITYA-L1: India’s first solar space mission

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

Magnetic reconnection as Cosmic lighthouse

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...


I-Love-C universal relation for the anisotropic neutron stars

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...


Origin of ultra-bright blazar emissions: An astronomer’s glimpse into cosmic volcanoes

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...


The Ghost of a Star Screams 6 Days After Its Death

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...


Why do some Active Galactic Nuclei Change their Look?

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...


Can missing physics in gravitational waveforms mimic false violations of general relativity?

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...


Using a pseudo-Kerr formalism to study accretion and wind flows around rotating black holes

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....


Astrophysical autopsy of a cosmic demise

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....


3.6m DOT discovered unexpected kilonova emission from a long-duration gamma-ray burst

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...


Fantastic beasts and where to find them: the elusive nature of X-ray quiet black holes

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,...


Insight into the pulsar emmision mechanism using subpulse drifting: Subpulse drifting in PSR J1822−2256

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...


Core-collapse supernova from a possible progenitor star of 100 solar mass

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...


Revealing the nature of the brightest & explosive astronomical sources in the sky using 3.6m Devasthal Optical Telescope (DOT)

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),...


General Relativity And Its Effect On A Deformed And Misaligned Pulsar

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...


Understanding the emissions in Black hole binaries

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.


Understanding the evolution of the binary star system ‘Cen X-3’: New measurements of the spin and orbital parameters of the system

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...


How strong is a neutron star's magnetic field?

Estimating the strength of the magnetic field of a neutron star in a binary star system ‘Cen X-3’


Futuristic gravitational wave observations to resolve dichotomy of compact objects

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

Bending/Flipping/Reorienting: Superheated plasma outflow from supermassive blackhole producing ‘X’-like fountains

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.


Rockets in the Interstellar Medium

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...


Collisions between galaxies: A frequent phenomenon than we expected earlier

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...


Origin of ultra-bright blazar emissions: An astronomer’s glimpse into cosmic volcanoes

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...


Looking at five radio-quiet AGN through the polarization lens

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...


Why do some Active Galactic Nuclei Change their Look?

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...


Imploding Cometary Clouds: An Astronomer's Perspective

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...


Accounting for the presence of dust in galaxies

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...


Astronomers find cold atomic gas playing peek-a-boo around a powerful quasar

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...


A comparison of the properties of Narrow Line and the Broad Line Seyfert galaxies

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...


What makes radio-quiet AGN radio-quiet? A polarization perspective

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...


Star-forming S0 Galaxies in SDSS-MaNGA: fading spirals or rejuvenated S0s?

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...


Why are some jets curved: presence of dancing blackholes?

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...


Clouds’ Motion entangled by Magnetic Fields in Cepheus Flare

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...


Bending of Cosmic fountains, giving birth to a peculiar X-shaped galaxy

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....


EARTH-SIZED TELESCOPES FOR ASTRONOMICAL OBSERVATIONS IN THE LOW RADIO FREQUENCIES

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...


Mass of the Black Hole in the nearby AGN: Mrk 590

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...


Bar Buckling and Boxy/Peanut Bulges as the Tracer of Dark Matter Halo Shape

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

Using Light to Trace Dark Matter

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...


Exploring the topology of hydrogen distribution in the early universe

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...


Gravitational Waves in an Inhomogeneous Universe

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 telescope refutes astrophysical origins of the claimed cosmic dawn signal

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...


Shedding Light on the Cosmic Web with Fast Radio Bursts

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

Astrobiology: Exploring the universe for signs of extra-terrestrial life

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...


Sir C. V. Raman: Raman effect and beyond

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)

Vainu Bappu Observatory: the telescope town of India

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

Spreading the joy of science - The science outreach activities during the Young Astronomer’s Meeting, 2022

A summary of science outreach performed during the Young Astronomer’s Meeting, 2022.


Category Radio survey

MALS Unveiled: Revealing Half a Million Cosmic Radio Sources

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

MALS Unveiled: Revealing Half a Million Cosmic Radio Sources

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...