134 research outputs found
Is PMI a good leading indicator of industrial production?: Evidence from India
The manufacturing Purchasing Managers’ Index is often used by policy makers to gauge the ‘nerve’ of the real economy and as lead indicator of industrial activity. This paper makes an effort to evaluate whether the PMI is indeed a good lead indicator of IIP or whether by relying on PMI the policy makers are making a systematic error. Using ARDL technique, this paper largely support the claim that the PMI is a good lead indicator of industrial activity, albeit only in the short run
Is PMI a good leading indicator of industrial production?: Evidence from India
The manufacturing Purchasing Managers’ Index is often used by policy makers to gauge the ‘nerve’ of the real economy and as lead indicator of industrial activity. This paper makes an effort to evaluate whether the PMI is indeed a good lead indicator of IIP or whether by relying on PMI the policy makers are making a systematic error. Using ARDL technique, this paper largely support the claim that the PMI is a good lead indicator of industrial activity, albeit only in the short run
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We give a 5 k n O(1) time fixed-parameter algorithm for determining whether a given undirected graph on n vertices has a subset of at most k vertices whose deletion results in a tree. Such a subset is a restricted form of a feedback vertex set. While parameterized complexity of feedback vertex set problem and several of its variations have been well studied, to the best of our knowledge, this is the first fixed-parameter algorithm for this version of feedback vertex set. Submitted
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
Stellar contents and star formation in the young star cluster Be 59
We present CCD photometry of the young open cluster Be 59 with the
aim to study the star formation scenario in the cluster. The radial extent of
the cluster is found to be 10 arcmin (2.9 pc). The interstellar
extinction in the cluster region varies between 1.4 to 1.8 mag.
The ratio of total-to-selective extinction in the cluster region is estimated
as . The distance of the cluster is found to be kpc.
Using near-infrared colours and slitless spectroscopy, we have identified young
stellar objects (YSOs) in the open cluster Be 59 region. The ages of these YSOs
range between Myr to 2 Myr, whereas the mean age of the massive
stars in the cluster region is found to be 2 Myr. There is evidence for
second generation star formation outside the boundary of the cluster, which may
be triggered by massive stars in the cluster. The slope of the initial mass
function, , in the mass range is found to be
which is shallower than the Salpeter value (-1.35), whereas in
the mass range the slope is almost flat. The slope of
the K-band luminosity function is estimated as , which is smaller
than the average value (0.4) reported for young embedded clusters.
Approximately 32% of H emission stars of Be 59 exhibit NIR excess
indicating that inner disks of the T-Tauri star (TTS) population have not
dissipated. The MSX and IRAS-HIRES images around the cluster region are also
used to study the emission from unidentified infrared bands and to estimate the
spatial distribution of optical depth of warm and cold interstellar dust.Comment: Accepted for the publication in MNRAS, 39 pages, 26 Figures, 8 Table
Star Formation Activity in the Galactic HII Complex S255-S257
We present results on the star-formation activity of an optically obscured
region containing an embedded cluster (S255-IR) and molecular gas between two
evolved HII regions S255 and S257. We have studied the complex using optical,
near-infrared (NIR) imaging, optical spectroscopy and radio continnum mapping
at 15 GHz, along with Spitzer-IRAC results. It is found that the main exciting
sources of the evolved HII regions S255 and S257 and the compact HII regions
associated with S255-IR are of O9.5 - B3 V nature, consistent with previous
observations. Our NIR observations reveal 109 likely young stellar object (YSO)
candidates in an area of ~ 4'.9 x 4'.9 centered on S255-IR, which include 69
new YSO candidates. Our observations increased the number of previously
identified YSOs in this region by 32%. To see the global star formation, we
constructed the V-I/V diagram for 51 optically identified IRAC YSOs in an area
of ~ 13' x 13' centered on S255-IR. We suggest that these YSOs have an
approximate age between 0.1 - 4 Myr, indicating a non-coeval star formation.
Using spectral energy distribution models, we constrained physical properties
and evolutionary status of 31 and 16 YSO candidates outside and inside the gas
ridge, respectively. The models suggest that the sources associated within the
gas ridge are of younger population (mean age ~ 1.2 Myr) than the sources
outside the gas ridge (mean age ~ 2.5 Myr). The positions of the young sources
inside the gas ridge at the interface of the HII regions S255 and S257, favor a
site of induced star formation.Comment: 46 pages, 14 figures, 5 tables. Accepted for publication in The
Astrophysical Journa
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
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