75 research outputs found
Multiwavelength study of a young open cluster NGC 7419
Using new UBVRI H αCCD photometric observations and the archival infrared and X-ray data, we have carried out a multiwavelength study of a Perseus arm young open star cluster NGC 7419. An age of 22.5 ± 3.0 Myr and a distance of 3230+330-430 pc are derived for the cluster. Our photometric data indicate a higher value of colour excess ratio E(U-B)/E(B-V) than the normal one. There is an evidence for mass segregation in this dynamically relaxed cluster and in the range 1.4-8.6 M⊚, the mass function slope is in agreement with the Salpeter value. Excess emissions in near-infrared and H α support the existence of a young (≤ 2 Myr) stellar population of Herbig Ae/Be stars (≥3.0 M⊚) indicating a second episode of star formation in the cluster region. Using XMM-Newton observations, we found several X-ray sources in the cluster region but none of the Herbig Ae/Be stars is detected in X-rays. We compare the distribution of upper limits for Herbig Ae/Be stars with the X-ray distribution functions of the T Tauri and the Herbig Ae/Be stars from previous studies, and found that the X-ray emission level of these Herbig Ae/Be stars is not more than LX~ 5.2 × 1030 ergs-1, which is not significantly higher than for the T Tauri stars. Therefore, X-ray emission from Herbig Ae/Be stars could be the result of either unresolved companion stars or a process similar to T Tauri stars. We report an extended X-ray emission from the cluster region NGC 7419, with a total X-ray luminosity estimate of ~1.8 × 1031 erg s-1 arcmin-2. If the extended emission is due to unresolved emission from the point sources then we estimate ~288 T Tauri stars in the cluster region each having X-ray luminosity ~1.0 × 1030 ergs-1. Investigation of dust attenuation and 12CO emission map of a square degree region around the cluster indicates the presence of a foreground dust cloud which is most likely associated with the local arm star-forming region (Sh2-154). This cloud harbours uniformly distributed pre-main-sequence stars (0.1-2.0 M⊚ ), with no obvious trend of their distribution with either (H-K) excess or AV. This suggests that the star formation in this cloud depend mostly upon the primordial fragmentation
Raspberry-Pi and IoT based Health Monitoring System
The observation of the patient wirelessly could be a major improvement within the medical domain. The sensors once integrated into a wireless communication network, helps to remotely collect physiological signals of patient and avoid observation exploitation ancient medical instruments that makes the patient tether. During this paper, the observation of the patient is finished by the doctor endlessly while not really visiting the patient. Here, we tend to square measure exploitation varied sensors to sense the physiological parameters like temperature, vital sign, graphical record and therefore the level of saline. These detected signals square measure transmitted to the Raspberry pi to update the info endlessly via ADC which can convert these analog signals into digital signals. Through transmitter, the info is distributed wirelessly to the monitor screen of the doctor. So, the doctor will visualize the patient’s knowledge simply by sitting in his cabin. Once a important condition happens, the visual indications are going to be sent onto the screen
RJK Observations of the Optical Afterglow of GRB 991216
We present near-infrared and optical observations of the afterglow to the
Gamma-Ray Burst (GRB) 991216 obtained with the F. L. Whipple Observatory 1.2-m
telescope and the University of Hawaii 2.2-m telescope. The observations range
from 15 hours to 3.8 days after the burst. The temporal behavior of the data is
well described by a single power-law decay with index -1.36 +/-0.04,
independent of wavelength. The optical spectral energy distribution, corrected
for significant Galactic reddening of E(B-V)=0.626, is well fitted by a single
power-law with index -0.58 +/- 0.08. Combining the IR/optical observations with
a Chandra X-ray measurement gives a spectral index of -0.8 +/- 0.1 in the
synchrotron cooling regime. A comparison between the spectral and temporal
power-law indices suggest that a jet is a better match to the observations than
a simple spherical shock.Comment: Accepted to the Astrophysical Journal, 12 pages, 4 postscript figure
Multi-wavelength study of a young open cluster NGC 7419
Using UBVRI Halpha CCD photometric observations and the archival NIR and
X-ray data, we have carried out a multi-wavelength study of a young star
cluster NGC 7419. An age of 22.5+/-3.0 Myr and a distance of 3230^{+330}_{-430}
pc are derived for the cluster with a higher value of color excess ratio
E(U-B)/E(B-V) than the normal one. There is an evidence for mass segregation in
this dynamically relaxed cluster with mass function slope is in agreement with
the Salpeter value. NIR and Halpha excess support the existence of a young (< 2
Myr) stellar population of Herbig Ae/Be stars (> 3.0 M_sun) indicating a second
episode of star formation in the cluster region. Using XMM-Newton observations,
we found several X-ray sources in the cluster region but none of the Herbig
Ae/Be stars is detected in X-rays. We compare the distribution of upper limits
for Herbig Ae/Be stars with the X-ray distribution functions of the T-Tauri and
the Herbig Ae/Be stars from previous studies, and found that the X-ray emission
level of these Herbig Ae/Be stars is not more than L_X ~5.2 x 10^{30} erg/s,
which is not significantly higher than for the T-Tauri stars. Therefore, X-ray
emission from Herbig Ae/Be stars could be the result of either unresolved
companion stars or a process similar to T-Tauri stars. We report an extended
X-ray emission from the cluster region NGC 7419, with a total L_X estimate of ~
1.8 x 10^31 erg/s/arcmin^2. Investigation of dust and CO map of 1 degree region
around the cluster indicates the presence of a foreground dust cloud which is
most likely associated with star forming region Sh2-154. This cloud harbors
uniformly distributed pre main sequence stars (0.1-2.0M_sun) and the star
formation in this cloud depend mostly upon the primordial fragmentation.Comment: 23 pages, 23 figures, 13 tables; Accepted for publication in MNRA
Mass functions and photometric binaries in nine open clusters
Using homogeneous CCD photometric data from the 105-cm Kiso Schmidt telescope
covering a 50' x 50' field, we study the mass functions (MFs) of nine open
clusters. The ages and Galactocentric distances of the target clusters vary
from 16 - 2000 Myr and 9-10.8 kpc, respectively. The values of MF slopes vary
from -1.1 to -2.1. The classical value derived by Salpeter (1955) for the slope
of the IMF is \Gamma = -1.35. The MFs in the outer regions of the clusters are
found to be steeper than in the inner regions, indicating the presence of mass
segregation in the clusters.The MF slopes (in the outer region as well as the
whole cluster) undergo an exponential decay with the evolutionary parameter
\tau (= age/ relaxation time). It seems that the evaporation of low-mass
members from outer regions of the clusters is not significant at larger
Galactocentric distances. It is concluded that the initial mass function (IMF)
in the anticentre direction of the Galaxy might have been steeper than the IMF
in the opposite direction. A comparison of the observed CMDs of the clusters
with synthetic CMDs gives a photometric binary content of ~40%.Comment: Accepted for the publication in AJ, 21 Pages, 11 Figures, 9 Table
Star formation in young star cluster NGC 1893
We present a comprehensive multi-wavelength study of the star-forming region
NGC 1893 to explore the effects of massive stars on low-mass star formation.
Using near-infrared colours, slitless spectroscopy and narrow-band
photometry in the cluster region we have identified candidate young stellar
objects (YSOs) distributed in a pattern from the cluster to one of the nearby
nebulae Sim 129. The colour-magnitude diagram of the YSOs indicates
that majority of these objects have ages between 1 to 5 Myr. The spread in the
ages of the YSOs may indicate a non-coeval star formation in the cluster. The
slope of the KLF for the cluster is estimated to be , which agrees
well with the average value () reported for young clusters. For the
entire observed mass range the value of the slope of
the initial mass function, ', comes out to be , which is
in agreement with the Salpeter value of -1.35 in the solar neighborhood.
However, the value of ' for PMS phase stars (mass range ) is found to be which is shallower than the
value () obtained for MS stars having mass range indicating a break in the slope of the mass function at . Estimated ' values indicate an effect of mass segregation
for main-sequence stars, in the sense that massive stars are preferentially
located towards the cluster center. The estimated dynamical evolution time is
found to be greater than the age of the cluster, therefore the observed mass
segregation in the cluster may be the imprint of the star formation process.
There is evidence for triggered star formation in the region, which seems to
govern initial morphology of the cluster.Comment: Accepted for the publication in MNRAS, 21 pages, 26 figures, 10
table
Rapid UBVRI Follow-up of the Highly Collimated Optical Afterglow of GRB010222
(Abridged) We present the earliest optical observations of the optical
counterpart to the GRB 010222, obtained with the FLWO 1.2-m telescope in UBVRI
passbands, starting 3.64 hours after the burst. We also present late R-band
observations of the afterglow obtained with the 1.8-m VATT ~25 days after the
burst. The temporal analysis of our data joined with published data indicates a
steepening decay, independent of wavelength, asymptotically approaching
t^{-0.80+/-0.05} at early times (t << 1 day) and t^{-1.30+/-0.05} at late
times, with a sharp break at t_b=0.72+/-0.1 days. This is the second earliest
observed break of any afterglow (after GRB 980519), which clearly indicates the
importance of rapid multi-band follow-up for GRB afterglow research. The
optical spectral energy distribution, corrected for small Galactic reddening,
can be fit fairly well by a single power-law with a slope of -1.07+/-0.09.
However, when we fit using our BVRI data only, we obtain a shallower slope of
-0.88+/- 0.1, in excellent agreement with the slope derived from our
low-resolution spectrum (-0.89 +/- 0.03). The spectral slope and light curve
decay slopes we derive are not consistent with a jet model despite the presence
of a temporal break. Significant host dust extinction with a star-burst
reddening law would flatten the spectral index to match jet predictions and
still be consistent with the observed spectral energy distribution. We derive
an opening angle of 2.1 deg, smaller than any listed in the recent compilation
of Frail et al. The total beamed energy corrected for the jet geometry is
4x10^50 erg, very close to the ``standard'' value of 5x10^50 erg found by Frail
et al. for a number of other bursts with light-curve breaks.Comment: revised version (minor changes only) to be published in the ApJ Part
1, 12 pages, 4 figures; all data used for the fits and our CCD frames
available at ftp://cfa-ftp.harvard.edu/pub/kstanek/GRB010222/ and through WWW
at http://cfa-www.harvard.edu/cfa/oir/Research/GRB
- …