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Unravelling the nature of explosion of thermonuclear supernovae

Dutta, Anirban (Indian Institute of Astrophysics, 2023-05)

Type Ia supernovae (SNe Ia) result from thermonuclear explosions in binary systems consisting of at least one carbon-oxygen white dwarf. They are crucial for the understanding of galactic chemical composition as they are ...

Unravelling the nuclear dust morphology of NGC 1365: a two-phase polar–RAT model for the ultraviolet to infrared spectral energy distribution

Swain, Subhashree; Shalima, P; Latha, K. V. P (Oxford University Press on behalf of Royal Astronomical Society, 2024-01)

We present a 3D radiative transfer model for the spectral energy distribution (SED) of NGC 1365, which is a ‘changing look’ Seyfert 1.8 type active galactic nucleus (AGN). The SED from the ultraviolet (UV) to the infrared ...

Unravelling the post-collision properties of the Cartwheel galaxy: A MUSE exploration of its bar and inner region

Mondal, Chayan; Barway, Sudhanshu (EDP Sciences, 2024-01)

Aims. We aim to investigate the characteristics of the bar and inner disc in the collisional ring galaxy Cartwheel. Methods. We used integral field unit (IFU) observations from the Multi-Unit Spectroscopic Explorer (MUSE) ...

Unravelling the unusually curved X-ray spectrum of RGB J0710 + 591 using AstroSat observations

Goswami, Pranjupriya; Sinha, Atreyee; Chandra, Sunil; Misra, Ranjeev; Chitnis, Varsha; Gogoi, Rupjyoti; Sahayanathan, Sunder; Stalin, C. S; Singh, K. P; Yada, J. S (Oxford University Press on behalf of the Royal Astronomical Society, 2020-02)

We report the analysis of simultaneous multiwavelength data of the high-energy-peaked blazar RGB J0710 + 591 from the Large Area X-ray Proportional Counters, Soft X-ray focusing Telescope, and Ultraviolet Imaging ...

Unusual bright filaments on the sun on 1926 February 22

Royds, T (Royal Astronomical Society, 1926)

Unusual extinction profiles by Rayleigh scattering

Shah, G. A (WILEY-VCH Verlag Berlin GmbH & Co, 1977)

The extinction efficiencies for small smooth metallic particles (granules) have been calculated using rigorous Mie theory of scattering. Strong size-dependent resonances for spheres composed of sodium, potassium, and calcium ...

Unusual long-term low-activity states of EGRET blazars in the Fermi era

Bhattacharya, Debbijoy; Mohana A, K; Gulati, S; Bhattacharyya, Subir; Bhatt, N; Sreekumar, P; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2017-11)

We examine the long-term (∼10 years) γ-ray variability of blazars observed by the Energetic Gamma Ray Experiment Telescope (EGRET) and Fermi and find that 10 EGRET-detected flat-spectrum radio quasars (FSRQs) were not ...

Unusual optical quiescence of the classical BL Lac object PKS 0735+178 on intranight time scale

Goyal, A; Gopal-Krishna; Anupama, G. C; Sahu, D. K; Sagar, R; Britzen, S; Karouzos, M; Aller, M. F; Aller, H. D (Wiley Blackwell, 2009-07)

We present the result of our extensive intranight optical monitoring of the well known low-energy peaked BL Lac (LBL) object PKS 0735+178. This long-term follow-up consists of $R$-band monitoring for a minimum duration of ...

Unusual solar activity

Salaruddin, MD; Narayan, B. G (Calcutta University Press, 1939-12)

The paper describes briefly the outstanding features of a recent persistent solar activity observed in Kodaikanal. Attempts have been made to correlate the bright chromospheric eruptions with the terrestrial effects. It ...

An unusual very low-mass high-amplitude pre-main sequence periodic variable

Rodríguez-Ledesma, M. V; Mundt, R; Ibrahimov, M; Messina, S; Parihar, P. S; Hessman, F. V; Alves de Oliveira, C; Herbst, W (EDP Sciences, 2012-08)

Aims. We have investigated the nature of the variability of CHS 7797, an unusual periodic variable in the Orion Nebula Cluster. Methods. An extensive I-band photometric data set of CHS 7797 was compiled between 2004−2010 ...

The unusually large population of Blazhko variables in the globular cluster NGC 5024 (M53)

Arellano Ferro, A; Bramich, D. M; Figuera Jaimes, R; Giridhar, S; Kuppuswamy, K (Wiley-Blackwell, 2012-02)

We report the discovery of amplitude and phase modulations typical of the Blazhko effect in 22 RRc and nine RRab type RR Lyrae stars in NGC 5024 (M53). This brings the confirmed Blazhko variables in this cluster to 23 RRc ...

Unveiling an Old Disk around a Massive Young Leaking Blueberry in SDSS-IV MaNGA

Paswan, Abhishek; Saha, Kanak; Borgohain, Anshuman; Leitherer, Claus; Dhiwar, Suraj (American Astronomical Society, 2022-04-10)

Extreme emission-line galaxies, such as blue compact dwarfs (BCDs), Green Peas (GPs), and blueberries in the local universe are potential candidates for understanding the nature of galaxies that reionized the early universe. ...

Unveiling the dynamics and genesis of small-scale fine-structure loops in the lower solar atmosphere

Bura, Annu; Samanta, T; Sterling, Alphonse C; Chen, Yajie; Joshi, Jayant; Yurchyshyn, Vasyl; Moore, Ronald L (American Astronomical Society, 2025-04-20)

Recent high-resolution solar observations have unveiled the presence of small-scale loop-like structures in the lower solar atmosphere, often referred to as unresolved fine structures, low-lying loops, and miniature hot ...

Unveiling the kinematics of a central region in the triple-AGN host NGC 7733-7734 interacting group

Keshri, Saili; Barway, Sudhanshu; Mousumi Das; Yadav, Jyoti; Combes, Francoise (EDP Sciences, 2025-03)

We present a detailed study of the interacting triple active galactic nuclear system, NGC 7733-34, focusing on stellar kinematics, ionised gas characteristics, and star formation within the central region and stellar bars ...

Unveiling the nature of two dwarf novae: CRTS J080846.2+313106 and V416 Dra

Joshi, Arti; Catelan, Marcio; Scaringi, Simone; Schwope, Axel; Anupama, G. C; Rawat, Nikita; Sahu, D. K; Singh, Mridweeka; Dastidar, Raya; Subramanian, Rama Venkata; Rao, Srinivas M (EDP Sciences, 2024-09)

We present the analysis of optical photometric and spectroscopic observations of two non-magnetic cataclysmic variables, namely CRTS J080846.2+313106 and V416 Dra. We find CRTS J080846.2+313106 to vary with a period of ...

Unveiling Vela – time variability of Na I D lines in the direction of the Vela supernova remnant

Kameswara Rao, N; Muneer, S; Lambert, D. L; Varghese, B. A (Oxford University Press on behalf of the Royal Astronomical Society, 2016-01-21)

High-resolution spectral profiles of Na I D lines from the interstellar medium towards 64 stars in the direction of the Vela supernova remnant are presented. This survey conducted mostly between 2011 and 12 complements an ...

Unveiling Vela – variability of interstellar lines in the direction of the Vela supernova remnant – III. Na D and Ca II K

Kameswara Rao, N; Lambert, D. L; Reddy, A. B. S; Gupta, R; Muneer, S; Singh, H. P (Oxford University Press on behalf of the Royal Astronomical Society, 2020-03)

High-resolution optical spectra were obtained in 2017–2019 with The Southern African Large Telescope of 15 stars in the direction of the Vela supernova remnant. Interstellar Ca II H & K and Na I D lines are discussed in ...

Unveiling Vela: time variability of interstellar lines in the direction of the Vela supernova remnant – II. Na D and Ca II

Kameswara Rao, N; Lambert, D. L; Reddy, A. B. S; Gupta, R; Muneer, S; Singh, H. P (IOP Publishing, 2017-05)

In a survey conducted between 2011 and 2012 of interstellar Na I D line profiles in the direction of the Vela supernova remnant (SNR), a few lines of sight showed dramatic changes in low-velocity absorption components with ...

UOCS X. Rich collection of post-mass-transfer systems in NGC 6791

Jadhav, Vikrant V; Subramaniam, A; Sagar, Ram (EDP Sciences, 2023-08)

Aims. NGC 6791 is one of the richest old open clusters in the Milky Way. Its position above the Galactic plane and its number density make it an interesting middle ground between Galactic open and globular clusters. We aim ...

UOCS XIV. Uncovering extremely low-mass white dwarfs and blue lurkers in NGC 752

Jadhav, Vikrant V; Subramaniam, A; Sagar, R (EDP Sciences, 2024-08)

Context. Evolutionary pathways of binary systems are vastly different from single stellar evolution, and thus there is a need to quantify their frequency and diversity. Thanks to their to their coeval nature, open clusters ...

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