Search Publications
Disentangling the neighbouring pulsars SXP 15.3 and SXP 305
Udalski, A.; Coe, M. J.; Roy, A. +8 more
SXP 15.3 and SXP 305 are two Be X-ray binaries in the Small Magellanic Cloud that are spatially separated by ~7 arcsec. The small separation between these sources has, in the past, resulted in confusion about the origin of the emission from the combined region. We present long-term optical and X-ray monitoring results of both sources, where we stu…
The outer orbit of the high-mass stellar triple system Herschel 36 determined with the VLTI
Brandner, W.; Pott, J. -U.; Alberdi, A. +8 more
Multiplicity is a ubiquitous characteristic of massive stars. Multiple systems offer us a unique observational constraint on the formation of high-mass systems. Herschel 36 A is a massive triple system composed of a close binary (Ab1-Ab2) and an outer component (Aa). We measured the orbital motion of the outer component of Herschel 36 A using infr…
Study of UV bright sources in globular cluster NGC 4590 using Ultraviolet Imaging Telescope (UVIT) observations
Pradhan, Ananta C.; Mohapatra, Abhisek; Parthasarathy, M. +5 more
We have studied ultraviolet (UV) bright sources in the Galactic globular cluster (GGC) NGC 4590 using Ultraviolet Imaging Telescope onboard the AstroSat satellite. Using UV-optical colour-magnitude diagrams (CMDs), we have identified and characterized the sources of different evolutionary stages i.e. blue horizontal branch stars (BHBs), extremely …
Magnetic fields and young stellar objects in cometary cloud L1616
Soam, Archana; Saha, Piyali; Gopinathan, Maheswar +3 more
The Lynds' Dark Nebula (LDN) 1615/1616 and CB 28 (hereafter L1616) together form a cometary globule located at an angular distance of about 8° west of the Orion OB1 association, aligned roughly along the east-west direction, and showing a distinct head-tail structure. The presence of massive stars in the Orion belt has been considered to be respon…
Cool interstellar medium as an evolutionary tracer in ALMA-observed local dusty early-type galaxies
Popescu, Cristina C.; Davis, Timothy A.; Sansom, Anne E. +1 more
The content and distribution of cool interstellar medium (<30 K) can indicate the evolutionary mechanisms that transform late-type to early-type galaxies (ETGs). To investigate this, ALMA observations of 12CO[2-1] line emission were obtained for five dusty ETGs from a complete sample in low-density environments. Four of the ETGs have…
Discovery and origin of the radio emission from the multiple stellar system KQ Vel
Umana, G.; Owocki, S. P.; Fossati, L. +20 more
KQ Vel is a binary system composed of a slowly rotating magnetic Ap star with a companion of unknown nature. In this paper, we report the detection of its radio emission. We conducted a multifrequency radio campaign using the ATCA interferometer (band-names: 16 cm, 4 cm, and 15 mm). The target was detected in all bands. The most obvious explanatio…
Density exponent analysis: gravity-driven steepening of the density profiles of star-forming regions
Li, Guang-Xing; Zhou, Ji-Xuan
The evolution of molecular interstellar clouds is a complex, multiscale process. The power-law density exponent describes the steepness of density profiles, and it has been used to characterize the density structures of the clouds; yet its usage is usually limited to spherically symmetric systems. Importing the Level-Set Method, we develop a new f…
Stellar populations of the globular cluster NGC 5053 investigated using AstroSat-Ultra Violet Imaging Telescope
Nikitha, K. J.; Vig, S.; Ghosh, S. K.
Globular clusters (GCs), being old and densely packed, serve as ideal laboratories to test stellar evolution theories. Although there is enormous literature on GCs in optical bands, studies in the ultraviolet (UV) regime are sparse. In this work, we study the stellar populations of a metal-poor and a rather dispersed GC, NGC 5053, using the UV ins…
Water-maser survey towards off-plane O-rich AGBs around the orbital plane of the Sagittarius stellar stream
Zhang, Bo; Li, Jingjing; Wu, Yuanwei +1 more
A 22 GHz water-maser survey was conducted towards 178 O-rich asymptotic giant branch (AGB) stars with the aim of identifying maser emission associated with the Sagittarius stellar stream. In this survey, maser emissions were detected in 21 targets, 20 of which were new detections. We studied the Galactic distributions of H2O- and SiO-ma…
LAMOST J045019.27 + 394758.7, with peculiar abundances of N, Na, V, Zn, is possibly a Sculptor dwarf galaxy escapee
Shejeelammal, J.; Goswami, Aruna; Joshi, Santosh +5 more
We present the results of the high-resolution (R ~ 60 000) spectroscopic analysis of the star LAMOSTJ045019.27 + 394758.7 (hereafter J045) from the list of carbon stars of LAMOST DR2. From our analysis, we find that J045 does not exhibit the spectral characteristics of carbon stars. It is found to be a metal-poor ([Fe/H] = -1.05) giant that shows …