17,190 research outputs found
The young cluster NGC 2282 : a multi-wavelength perspective
We present the analysis of the stellar content of NGC~2282, a young cluster
in the Monoceros constellation, using deep optical and IPHAS photometry
along with infrared (IR) data from UKIDSS and -IRAC. Based on the
stellar surface density analysis using nearest neighborhood method, the radius
of the cluster is estimated as 3.15\arcmin. From optical spectroscopic
analysis of 8 bright sources, we have classified three early B-type members in
the cluster, which includes, HD 289120, a previously known B2V type star, a
Herbig Ae/Be star (B0.5 Ve) and a B5 V star. From spectrophotometric analyses,
the distance to the cluster has been estimated as 1.65 kpc. The -band
extinction map is estimated using nearest neighborhood technique, and the mean
extinction within the cluster area is found to be A 3.9 mag. Using
IR colour-colour criteria and H-emission properties, we have
identified a total of 152 candidate young stellar objects (YSOs) in the region,
of which, 75 are classified as Class II, 9 are Class I YSOs. Our YSO catalog
also includes 50 H-emission line sources, identified using slitless
spectroscopy and IPHAS photometry data. Based on the optical and near-IR
colour-magnitude diagram analyses, the cluster age has been estimated to be in
the range of 2 5 Myr, which is in agreement with the estimated age from
disc fraction ( 58\%). Masses of these YSOs are found to be
0.12.0 M. Spatial distribution of the candidate YSOs shows spherical
morphology, more or less similar to the surface density map.Comment: 16 pages, 19 Figure
Evidence of mobile carriers with Charge Ordering gap in Epitaxial PrCaMnO Thin Films
Epitaxial thin films of charge-ordered PrCaMnO have
been studied using variable temperature Scanning tunneling microscopy and
spectroscopy (STM/STS). The as grown films were found to be granular while the
annealed films show atomic terraces at all temperatures and are found to be
electronically homogeneous in 78-300K temperature range. At high temperatures
(TT 230 K) the local tunnel spectra of the annealed films show
a depression in the density of states (DOS) near Fermi energy implying a
pseudogap with a significant DOS at E. The gap feature becomes more robust
with cooling with a sharp jump in DOS at E at T and with a gap value
of 0.3 eV at 78K. At low temperatures we find a small but finite DOS at
E indicative of some delocalized carriers in the CO phase together with an
energy gap. This is consistent with bulk transport, which shows weakening of
the activation gap with cooling below 200K, and indicates the presence of two
types of carriers at low temperatures.Comment: 4 pages, 4 figure
Incidence of HI 21-cm absorption in strong FeII systems at
We present the results from our search for HI 21-cm absorption in a sample of
16 strong FeII systems ((MgII ) \AA\ and
(FeII ) or \AA) at
using the Giant Metrewave Radio Telescope and the Green Bank Telescope. We
report six new HI 21-cm absorption detections from our sample, which have
increased the known number of detections in strong MgII systems at this
redshift range by %. Combining our measurements with those in the
literature, we find that the detection rate of HI 21-cm absorption increases
with , being four times higher in systems with
\AA\ compared to systems with \AA. The (HI)
associated with the HI 21-cm absorbers would be
cm, assuming a spin temperature of K (based on HI 21-cm
absorption measurements of damped Lyman- systems at this redshift
range) and unit covering factor. We find that HI 21-cm absorption arises on an
average in systems with stronger metal absorption. We also find that quasars
with HI 21-cm absorption detected towards them have systematically higher
values than those which do not. Further, by comparing the velocity
widths of HI 21-cm absorption lines detected in absorption- and galaxy-selected
samples, we find that they show an increasing trend (significant at
) with redshift at , which could imply that the absorption
originates from more massive galaxy haloes at high-. Increasing the number
of HI 21-cm absorption detections at these redshifts is important to confirm
various trends noted here with higher statistical significance.Comment: 17 pages, 10 figures, 8 tables, accepted for publication in MNRA
Repeated DNA sequences in different Neurospora species
Repeated DNA sequences in different Neurospora specie
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