609 research outputs found
Star formation around mid-infrared bubble N37: Evidence of cloud-cloud collision
We have performed a multi-wavelength analysis of a mid-infrared (MIR) bubble
N37 and its surrounding environment. The selected 1515 area around
the bubble contains two molecular clouds (N37 cloud; V37-43 km
s, and C25.29+0.31; V43-48 km s) along the line of
sight. A total of seven OB stars are identified towards the bubble N37 using
photometric criteria, and two of them are spectroscopically confirmed as O9V
and B0V stars. Spectro-photometric distances of these two sources confirm their
physical association with the bubble. The O9V star is appeared to be the
primary ionizing source of the region, which is also in agreement with the
desired Lyman continuum flux analysis estimated from the 20 cm data. The
presence of the expanding HII region is revealed in the N37 cloud which could
be responsible for the MIR bubble. Using the CO line data and
photometric data, several cold molecular condensations as well as clusters of
young stellar objects (YSOs) are identified in the N37 cloud, revealing ongoing
star formation (SF) activities. However, the analysis of ages of YSOs and the
dynamical age of the HII region do not support the origin of SF due to the
influence of OB stars. The position-velocity analysis of CO data reveals
that two molecular clouds are inter-connected by a bridge-like structure,
favoring the onset of a cloud-cloud collision process. The SF activities (i.e.
the formation of YSOs clusters and OB stars) in the N37 cloud are possibly
influenced by the cloud-cloud collision.Comment: 18 pages, 13 figures, 2 tables, Accepted for publication in the Ap
Coral reef ecosystem - Monitoring and assessment using satellite data sets
Remaining in splendid isolation, the Andaman and Nicobar Islands have a great relevance
in the study of marine ecosystems. The islands, though remotely located in an ostensibly
pristine environment have born witness to serious issues with regard to their ecosystem
health. There are significant changes in the temperature and rain fall pattern in the islands
and predictive modelling has forecasted further damage in the near future. The inundation
of saline water into inland terrestrial ecosystems has created salinity stress to freshwater
species while reducing the water available for domestic consumption. Terrestrial flora and
fauna are vulnerable to the intruding saline waters. The marine ecosystem also faces grave
challenges. There are issues of anthropogenic pollution resulting in damage of corals, regime
shifts in community structure, water quality deterioration and other damage to marine
fauna
Scalable consistency maintenance in content distribution networks using cooperative leases
A multi-wavelength study of star formation activity in the S235 complex
We have carried out an extensive multi-wavelength study to investigate the
star formation process in the S235 complex. The S235 complex has a sphere-like
shell appearance at wavelengths longer than 2 m and harbors an O9.5V type
star approximately at its center. Near-infrared extinction map traces eight
subregions (having A 8 mag), and five of them appear to be
distributed in an almost regularly spaced manner along the sphere-like shell
surrounding the ionized emission. This picture is also supported by the
integrated CO and CO intensity maps and by Bolocam 1.1 mm
continuum emission. The position-velocity analysis of CO reveals an almost
semi-ring like structure, suggesting an expanding H\,{\sc ii} region. We find
that the Bolocam clump masses increase as we move away from the location of the
ionizing star. This correlation is seen only for those clumps which are
distributed near the edges of the shell. Photometric analysis reveals 435 young
stellar objects (YSOs), 59\% of which are found in clusters. Six subregions
(including five located near the edges of the shell) are very well correlated
with the dust clumps, CO gas, and YSOs. The average values of Mach numbers
derived using NH data for three (East~1, East~2, and Central~E) out of
these six subregions are 2.9, 2.3, and 2.9, indicating these subregions are
supersonic. The molecular outflows are detected in these three subregions,
further confirming the on-going star formation activity. Together, all these
results are interpreted as observational evidence of positive feedback of a
massive star.Comment: 28 pages, 15 figures, 3 tables, Accepted for publication in The
Astrophysical Journa
Interferon Gamma Release Assay (IGRA) friend or foe - Clinical application of IGRA in a tuberculosis endemic country
pyTANSPEC: A Data Reduction Package for TANSPEC
The TIFR-ARIES Near Infrared Spectrometer (TANSPEC) instrument provides
simultaneous wavelength coverage from 0.55 to 2.5 micron, mounted on India's
largest ground-based telescope, 3.6-m Devasthal Optical Telescope at Nainital,
India. The TANSPEC offers three modes of observations, imaging with various
filters, spectroscopy in the low-resolution prism mode with derived R~ 100-400
and the high-resolution cross-dispersed mode (XD-mode) with derived median R~
2750 for a slit of width 0.5 arcsec. In the XD-mode, ten cross-dispersed orders
are packed in the 2048 x 2048 pixels detector to cover the full wavelength
regime. As the XD-mode is most utilized as well as for consistent data
reduction for all orders and to reduce data reduction time, a dedicated
pipeline is at the need. In this paper, we present the code for the TANSPEC
XD-mode data reduction, its workflow, input/output files, and a showcase of its
implementation on a particular dataset. This publicly available pipeline
pyTANSPEC is fully developed in Python and includes nominal human intervention
only for the quality assurance of the reduced data. Two customized
configuration files are used to guide the data reduction. The pipeline creates
a log file for all the fits files in a given data directory from its header,
identifies correct frames (science, continuum and calibration lamps) based on
the user input, and offers an option to the user for eyeballing and
accepting/removing of the frames, does the cleaning of raw science frames and
yields final wavelength calibrated spectra of all orders simultaneously.Comment: 10 pages, 6 figures, accepted for publication in the Special Issue of
Journal of Astrophysics & Astronomy, 2022, Star formation studies in context
of NIR instruments on 3.6m DOT, held at ARIES, Nainital during 4-7, May, 202
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