5 research outputs found
Structural Analysis of Open Cluster Bochum 2
We present the results from our deep optical photometric observations of
Bochum 2 (Boc2) star cluster obtained using the m Devasthal Fast Optical
Telescope along with archival photometric data from Pan-STARRS2/2MASS/UKIDSS
surveys. We also used high-quality parallax and proper motion data from the
Data Release 3. We found that the Boc2 cluster has a small size
(1.1 pc) and circular morphology. Using parallax of member stars
and isochrone fitting method, the distance of this cluster is estimated as
kpc. We have found that this cluster holds young ( Myr) and
massive (OO) stars as well as an older population of low mass stars. We
found that the massive stars have formed in the inner region of the Boc2
cluster in a recent epoch of star formation. We have derived mass function
slope () in the cluster region as in the mass range
M/M. The tidal radius of the Boc2 cluster ()
is much more than its observed radius ( pc). This suggests that most
of the low-mass stars in this cluster are the remains of an older population of
stars formed via an earlier epoch of star formation.Comment: accepted for publication in Journal of Astrophysics and Astronom
Dissecting the morphology of star forming complex S193
We have studied a star-forming complex S193 using near-infrared (NIR)
observations and other archival data covering optical to radio wavelengths. We
identified stellar clusters in the complex using the NIR photometric data and
estimated the membership and distance of the clusters. Using the mid-infrared
(MIR) and far-infrared (FIR) images, the distribution of the dust emission
around H\,{\sc ii} regions is traced in the complex. The column
density and temperature maps analysis reveal 16 cold dust clumps in the
complex. The H image and 1.4 GHz radio continuum emission map are
employed to study the ionised gas distribution and infer the spectral type and
the dynamical age of each H\,{\sc ii} region/ionised clump in the complex. The
CO(J =32) and CO(J =10) molecular line data hint at the
presence of two velocity components around [-43,-46] and [-47,-50] km/s, and
their spatial distribution reveals two overlapping zones toward the complex. By
investigating the immediate surroundings of the central cluster [BDS2003]57 and
the pressure calculations, we suggest that the feedback from the massive stars
seems responsible for the observed velocity gradient and might have triggered
the formation of the central cluster [BDS2003]57.}Comment: Accepted for publication in MNRAS, 20 pages, 15 figure
Post-outburst evolution of bonafide FUor V2493 Cyg: A Spectro-photometric monitoring
We present here the results of eight years of our near-simultaneous
optical/near-infrared spectro-photometric monitoring of bonafide FUor candidate
`V2493 Cyg' starting from 2013 September to 2021 June. During our optical
monitoring period (between October 16, 2015 and December 30, 2019), the V2493
Cyg is slowly dimming with an average dimming rate of 26.6 5.6
mmag/yr in V band. Our optical photometric colors show a significant reddening
of the source post the second outburst pointing towards a gradual expansion of
the emitting region post the second outburst. The mid infra-red colors, on the
contrary, exhibits a blueing trend which can be attributed to the brightening
of the disc due to the outburst. Our spectroscopic monitoring shows a dramatic
variation of the H line as it transitioned from absorption feature to
the emission feature and back. Such transition can possibly be explained by the
variation in the wind structure in combination with accretion. Combining our
time evolution spectra of the Ca II infra-red triplet lines with the previously
published spectra of V2493 Cyg, we find that the accretion region has
stabilised compared to the early days of the outburst. The evolution of the O I
7773 \AA~ line also points towards the stabilization of the
circumstellar disc post the second outburst.Comment: 34 pages, 12 figures, 6 tables, accepted for publication in Ap
Exploring Stellar Cluster and Feedback-driven Star Formation in the Galactic Mid-infrared Bubble [HKS2019] E70
We present a comprehensive analysis of the Galactic mid-infrared bubble [HKS2019] E70 (E70) by adopting a multiwavelength approach to understand the physical environment and star formation scenario around it. We identified a small (radius ∼1.7 pc) stellar cluster inside the E70 bubble, and its distance is estimated as 3.26 ± 0.45 kpc. This cluster is embedded in the molecular cloud and hosts massive stars, as well as young stellar objects (YSOs), suggesting active star formation in the region. The spectral type of the brightest star (M1) of the E70 cluster is estimated as O9V, and a circular ring/shell of gas and dust is found around it. The diffuse radio emission inside this ring/shell, the excess pressure exerted by the massive star M1 at the YSO’s core, and the distribution of photodissociation regions, a class I YSO, and two ultracompact H ii regions on the rim of this ring/shell clearly suggest positive feedback of the massive star M1 in the region. We also found a low-density shell-like structure in the ^12 CO( J = 1–0) molecular emission along the perimeter of the E70 bubble. The velocity structure of the ^12 CO emission suggests that the feedback from the massive star appears to have expelled the molecular material, and the subsequent swept-up material is what appears as the E70 bubble