Muneer Salim

Muneer Salim
Indian Institute of Astrophysics | IIAP · Research Division Space Astronomy

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Publications

Publications (78)
Article
We present the results obtained from our campaign to characterize the intra-night optical variability properties of blazars detected by the Fermi large area telescope. This involves R-band monitoring observations of a sample of 18 blazars, which includes five flat spectrum radio quasars (FSRQs) and thirteen BL Lac objects (BL Lacs) covering the red...
Article
We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/Gas Slit Camera observations in soft and hard X-rays from MAXI J0709–159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the flare was around 1037 erg s−1 (MAXI), which got reduced to 1032 erg s−1 (NuSTAR) after the flare....
Article
Full-text available
We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/Gas Slit Camera observations in soft and hard X-rays from MAXI J0709–159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the flare was around 10 ³⁷ erg s ⁻¹ (MAXI), which got reduced to 10 ³² erg s ⁻¹ (NuSTAR) after the fl...
Preprint
We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/GSC observations in soft and hard X-rays from MAXI J0709-159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the flare was around 10^(37) erg/s (MAXI), which got reduced to 10^(32) erg/s (NuSTAR) after the flare. We took l...
Article
An observatory class national large optical-IR telescope (NLOT), is proposed to be built and located in the country. The telescope consists of a 10–12 m segmented primary. In order to cater to a diversity of observational programs, the telescope is designed with high throughput in both the optical and IR regions (0.3–5 μm). It should perform reason...
Preprint
Full-text available
We present the results obtained from our campaign to characterize the intra-night-optical variability properties of blazars detected by the {\it Fermi} Large Area Telescope. This involves R-band monitoring observations of a sample of 18 blazars, that includes five flat-spectrum radio quasars (FSRQs) and thirteen BL Lac objects (BL Lacs) covering th...
Article
We present a CCD VI photometric study of the globular cluster M14. Particular attention is given to the variable stars. This allowed new classifications and cluster membership considerations. New variables are reported; 3 RRc, 18 SR and 1 SX Phe. The Fourier decomposition of RR Lyrae light curves lead to the mean cluster metallicity of [Fe/H]ZW = −...
Preprint
We present a CCD $VI$ photometric study of the globular cluster M14. Particular attention is given to the variable stars. This allowed new classifications and cluster membership considerations. New variables are reported; 3 RRc, 18 SR and 1 SX Phe. The Fourier decomposition of RR Lyrae light curves lead to the mean cluster metallicity of [Fe/H]$_{\...
Article
Full-text available
We report results of the dust reverberation mapping (DRM) on the Seyfert 1 galaxy Z229−15 at z = 0.0273. Quasi-simultaneous photometric observations for a total of 48 epochs were acquired during the period 2017 July to 2018 December in B, V, J, H and Ks bands. The calculated spectral index (α) between B and V bands for each epoch was used to correc...
Preprint
Full-text available
We report results of the dust reverberation mapping (DRM) on the Seyfert 1 galaxy Z229-15 at z = 0.0273. Quasi-simultaneous photometric observations for a total of 48 epochs were acquired during the period 2017 July to 2018 December in B, V, J, H and Ks bands. The calculated spectral index ({\alpha}) between B and V bands for each epoch was used to...
Article
Full-text available
Time-series VI CCD photometry of the globular cluster M10 (NGC 6254) is employed to perform a detailed identification, inspection of their light curves, their classification and their cluster membership, of all the known variables reported up to 2018. The membership analysis is based on the Gaia-DR2 positions and proper motions. The metallicity of...
Preprint
Full-text available
Time-series VI CCD photometry of the globular cluster M10 (NGC 6254) is employed to perform a detailed identification, inspection of their light curves, their classification and their cluster membership, of all the known variables reported up to 2018. The membership analysis is based on the Gaia-DR2 positions and proper motions. The metallicity of...
Article
Full-text available
We present medium resolution (1000) K-band spectra of 12 post-AGB candidates and related stars. For several objects in our sample, these spectra were obtained for the first time. The Br\(\gamma \) line in emission is detected in seven objects indicating the onset of photo-ionization in these objects. Four objects show the presence of an He i line....
Preprint
We present medium resolution (1000) K-band spectra of 12 post-AGB candidates and related stars. For several objects in our sample, these spectra were obtained for the first time. The Br$\gamma$ line in emission is detected in seven objects indicating the onset of photo-ionization in these objects. Four objects show the presence of He i line. We det...
Article
From an analysis of absorption lines in the high-resolution spectra, we have derived the radial velocities, stellar parameters (Teff, log g, wind-strength parameter log Q, and projected rotational velocity), and abundances (C, N, O, and Si) of IRAS 17460-3114, IRAS 18131-3008, IRAS 19336-0400, LSE 45, and LSE 163. Abundances are found to be solar,...
Article
We present an analysis of ${VI}$ CCD time-series photometry of globular cluster NGC 6712. Our main goal is to study the variable star population as indicators of the cluster mean physical parameters. We employed the Fourier decomposition of RR Lyrae light curves to confirm that ${}[\rm Fe/H]_{UVES} = -1.0 \pm 0.05$ is a solid estimate. We estimated...
Preprint
From an analysis of absorption lines in the high resolution spectra we have derived the radial velocities, stellar parameters (Teff, gravity, wind-strength parameter logQ and projected rotational velocity) and abundances (C, N, O, and Si ) of IRAS 17460-3114, IRAS 18131-3008, IRAS 19336-0400, LSE 45 and LSE 163. Abundances are found to be solar, ex...
Article
High-resolution optical spectra were obtained in 2017–2019 with The Southern African Large Telescope of 15 stars in the direction of the Vela supernova remnant. Interstellar Ca ii H & K and Na i D lines are discussed in this paper. In particular, the line profiles are compared with profiles at a comparable spectral resolution obtained in 1993–1996...
Preprint
Full-text available
We present an analysis of $\emph{VI}$ CCD time series photometry of globular cluster NGC 6712. Our main goal is to study the variable star population as indicators of the cluster mean physical parameters. We employed the Fourier decomposition of RR Lyrae light curves to confirm that $[\rm Fe/H]_{UVES} = -1.0 \pm 0.05$ is a solid estimate. We estima...
Preprint
Full-text available
High-resolution optical spectra were obtained in 2017-2019 with The Southern African Large Telescope of fifteen stars in the direction of the Vela supernova remnant. Interstellar Ca ii H and K and Na i D lines are discussed in this paper. In particular, the line profiles are compared with profiles at a comparable spectral resolution obtained in 199...
Article
We present the results from VI CCD time-series photometry of the globular cluster M13 (NGC6205). From the Fourier decomposition of the light curves of RRab and RRc stars we found an average metallicity of [Fe/H]zw = -1.58±0.09. The distance to the cluster was estimated as 7.1±0.1 kpc from independent methods related to the variable star families RR...
Preprint
Full-text available
We present the results from $VI$ CCD time-series photometry of the globular cluster M13 (NGC 6205). From the Fourier decomposition of the light curves of RRab and RRc stars we found an average metallicity of [Fe/H]zw = -1.58 $\pm$ 0.09. The distance to the cluster was estimated as 7.1 $\pm$ 0.1 kpc from independent methods related to the variable s...
Preprint
We present the results from V I CCD time-series photometry of the globular cluster M13 (NGC 6205). From the Fourier decomposition of the light curves of RRab and RRc stars we found an average metallicity of [Fe/H]zw =-1.58 ± 0.09. The distance to the cluster was estimated as 7.1 ± 0.1 kpc from independent methods related to the variable star famili...
Preprint
We present new CCD $VI$ photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H]=-1.65, and a distance of 23.67$\pm$0.57 kpc. Light and colour near minimum phases for RRab stars leads to an estimate of $E(B-V)$=0.104 $\pm$ 0.001. A $V/(V-I)$ col...
Article
We present new CCD VI photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H] = −1.65, and a distance of 23.67 ± 0.57 kpc. Light and colour near minimum phases for RRab stars leads to an estimate of E(B−V)=0.104 ± 0.001. A V/(V−I) colour-magnit...
Preprint
Full-text available
We present an analysis of VI CCD time-series photometry of the globular cluster NGC 6171. The main goal is to determine individual physical parameters for single-mode RR Lyrae stars present in the field of view of our images, by means of light curve Fourier decomposition and well-established calibrations and zero-points. This leads to the estimatio...
Article
We present an analysis of VI CCD time series photometry of the globular cluster NGC 6171. The main goal is to determine individual physical parameters for single‐mode RR Lyrae stars present in the field of view of our images, by means of light curve Fourier decomposition and well‐established calibrations and zero points. This leads to the estimatio...
Article
Full-text available
We have calculated the physical parameters of the RR Lyrae stars in the globular cluster NGC~4147 via the Fourier decomposition of their light curves, using new data and well-established semi-empirical calibrations and zero points. The mean metallicity and distance estimated using the RRc stars are [Fe/H]$_{ZW}=-1.72\pm0.15$ and $19.05\pm0.46$ kpc...
Article
Full-text available
We have investigated the role of a few prominent excitation mechanisms viz. collisional excitation, recombination, continuum fluorescence and Lyman beta fluorescence on the OI line spectra in Herbig Ae/Be stars. The aim is to understand which of them is the central mechanism that explains the observed OI line strengths. The study is based on an ana...
Article
Based on photometric data obtained between 1935 and 2017, O − C diagrams were built for 22 RR Lyrae stars in the globular cluster NGC 6171, leading to the discovery of secular period changes in four variables for which we have calculated period change rates β. In contrast, we find that 82% of the sample stars have stable periods over the last 82 ye...
Article
Full-text available
We report an analysis of new $V$ and $I$ CCD time-series photometry of the globular cluster NGC 6934. Through the Fourier decomposition of the RR Lyrae light curves, the mean values of [Fe/H] and the distance of the cluster were estimated, we found; [Fe/H]$_{UVES}$=-1.48$\pm$0.14 and $d$=16.03$\pm$0.42 kpc, and [Fe/H]$_{UVES}$=-1.43$\pm$0.11 and $d...
Article
Full-text available
We present results of our study of PDS 11 binary system, which belongs to a rare class of isolated, high galactic latitude T Tauri stars. Our spectroscopic analysis reveals that PDS 11 is a M2-M2 binary system with both components showing similar H-alpha emission strength. Both the components appear to be accreting, and are classical T Tauri stars....
Article
In a survey conducted between 2011-12 of interstellar Na I D line profiles in the direction of the Vela supernova remnant, a few lines of sight showed dramatic changes in low velocity absorption components with respect to profiles from 1993-1994 reported by Cha & Sembach. Three stars - HD 63578, HD 68217 and HD 76161 showed large decrease in streng...
Article
Full-text available
The gamma-ray blazar OJ 287 was in a high activity state during December 2015 - February 2016. Coinciding with this high brightness state, we observed this source for photometry on 40 nights in R-band and for polarimetry on 9 epochs in UBVRI bands. During the period of our observations, the source brightness varied between $13.20 \pm 0.04$ to $14.9...
Article
Full-text available
We report the distance and [Fe/H] value for the globular cluster NGC 5904 (M5) derived from the Fourier decomposition of the light curves of selected RRab and RRc stars. The aim in doing this was to bring these parameters into the homogeneous scales established by our previous work on numerous other globular clusters, allowing a direct comparison o...
Article
Full-text available
High-resolution spectral profiles of Na i D lines from the interstellar medium towards 64 stars in the direction of the Vela supernova remnant are presented. This survey conducted mostly between 2011 and 12 complements an earlier survey of the same stars by Cha & Sembach done in the 1993–96 period. The interval of 15–18 yr provides a base line to s...
Article
A new astronomical photo-polarimeter that can measure linear polarization of point sources simultaneously in three spectral bands was designed and built in Indian Institute of Astrophysics. The polarimeter has a Calcite beam-displacement prism as the analyzer. The ordinary and extra-ordinary emerging beams in each spectral band are quasi-simultaneo...
Article
We designed and built a new astronomical photo-polarimeter that can measure linear polarization simultaneously in three spectral bands. It has a Calcite beamdisplacement prism as the analyzer. The ordinary and extra-ordinary emerging beams in each spectral bands are quasi-simultaneously detected by the same photomultiplier by using a high speed rot...
Article
We report twelve variables not previously detected in the globular cluster M5 (NGC 5904); one SX Phe and eleven semi-regular variables (SR). Their identifications, equatorial coordinates, ephemerides, and light curves are given. Furthermore, we have explored the light curves of a group of stars whose variability has not been confirmed and that are...
Article
We designed and built a new astronomical photo-polarimeter that can measure linear polarization simultaneously in three spectral bands. It has a Calcite beam-displacement prism as the analyzer. The ordinary and extra-ordinary emerging beams in each spectral bands are quasi-simultaneously detected by the same photomultiplier by using a high speed ro...
Article
Full-text available
We have done a detailed abundance analysis of four unexplored candidate post- Asymptotic Giant Branch(AGB) stars IRAS 13110 - 6629, IRAS 17579 - 3121, IRAS 18321 - 1401 and IRAS 18489 - 0629 using high resolution spectra. We have constructed Spectral Energy Distributions (SED) for these objects using the existing photometric data combined with infr...
Article
Full-text available
Identification of metal-poor stars among field stars is extremely useful for studying the structure and evolution of the Galaxy and of external galaxies. We search for metal-poor stars using the artificial neural network (ANN) and extend its usage to determine absolute magnitudes. We have constructed a library of 167 medium-resolution stellar spect...
Article
Full-text available
An update on recent methods for automated stellar parametrization is given. We present preliminary results of the ongoing program for rapid parametrization of field stars using medium resolution spectra obtained using Vainu Bappu Telescope at VBO, Kavalur, India. We have used Artificial Neural Network for estimating temperature, gravity, metallicit...
Article
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Aims: We attempt to establish the real nature of the orbital period variation and its relation to the spot activity of V711 Tau, and determine why the (B-V) colour of the star appears to be nearly independent of its V magnitude. We wish to verify whether existing predictions in the literature for the long-term spot activity of the star are true or...
Article
We obtained new radial velocities of the G-type component of V711 Tau on 42 nights during 2004-09, and BV photometry of V711 Tau on 202 nights during the years 1993-2009. We measured the equivalent widths of two well resolved lines of the G-type component from 13 of the spectra obtained by us. We also measured the equivalent widths and base-line wi...
Article
Full-text available
We obtained the images of the eastern part of the solar corona in the Fexiv 530.3nm (green) and Fex 637.4nm (red) coronal emission lines during the total solar eclipse of 29 March 2006 at Manavgat, Antalya, Turkey. The images were obtained using a 35cm Meade telescope equipped with a Peltier-cooled 2k × 2k CCD and 0.3nm pass-band interference filte...
Article
The medium-resolution spectroscopic survey of our 180 ASAS stars was carried out using the 2-m Himalayan Chandra Telescope (HCT) of Indian Astronomical Observatory (IAO) equipped with the Himalaya Faint Object Spectrograph (HFOSC) spectrograph and the 2.3-m Vainu Bappu Telescope (VBT) of Vainu Bappu Observatory (VBO) equipped with the Optomechanics...
Article
We have started a spectroscopic survey to identify new chromospherically active components and low-mass pre-main sequence (PMS) stars in recently discovered All Sky Automated Survey (ASAS) eclipsing binaries. In this paper, we briefly describe our scientific motivation, the observing tools and the results obtained from the first phase of this surve...
Article
The recurrent nova RS Ophiuchi had its sixth recorded outburst on 2006 February 12, after an interval of 21 years. RS Ophiuchi is an interacting binary system with M2-3 giant secondary and an accreting, massive white dwarf primary. Recent results indicate this system to be a potential type Ia supernova progenitor. The latest outburst has been inte...
Article
The Na I D line profiles in the line of sight to few stars in the direction of Vela Supernovae remnant have been obtained including the HD 72127A, which is known to show such variations. Furthur changes in the profiles of HD 72127A have been seen. A programme to monitor more stars in the direction of Vela has been initiated. The time scale for vari...
Article
Full-text available
The morphology of the dust fans and shells in the images of comet C/2001 Q4 (NEAT) showed significant changes between 2004 April and June due to rapid changes in the Earth viewing and solar illumination geometry. We model the trajectories of dust grains ejected from distributed sources on the comet to explain the observed dust morphology in the ima...
Article
We consider the first 27-level atomic model of Fe XIII (5.9 K < log T_{e} < 6.4 K) to estimate its ground level populations, taking account of electron as well as proton collisional excitations and de-excitations, radiative cascades, radiative excitations and de-excitations. Radiative cascade is important but the effect of dilution factor is neglig...
Article
Full-text available
It is generally believed that the magnetic pressure is much higher than the gas pressure in the coronal loops and these loops are isothermal in nature. We made systematic observations of four strong coronal emission lines in the visible and near infrared part of the spectrum for about 8 years. Two emission lines were observed at a time, making rast...
Article
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Aims:In this paper we report the results of the spectroscopic survey we carried out to detect chromospheric activity of late-type stars in the fields of view of the CoRoT space mission. Methods: We give an accurate MK classification of all targets, which is valuable information on both the main CoRoT project and additional science programs, by mean...
Article
Photometric observations over three seasons show HD 288313 to be a light variable with a 2.2636-d period. The observed V amplitudes lie in the range of 0.06–0.15 mag. The star showed appreciable changes in the brightness at maximum and minimum of the light curve from season to season. The (b−y) colour did not show any significant variation during t...
Article
We present the results of our spectral classification which is made by using cross-correlation technique and the artificial neural networks (ANN). For 180 stars we give the spectral type from the literature, mostly are from SIMBAD, the spectral type and the correlation coefficient with respect to a template star that we found from cross-correlation...
Article
SN 2004et was observed with the 2-m Himalayan Chandra Telescope (HCT) of the Indian Astronomical Observatory (IAO), Hanle, India, using the Himalaya Faint Object Spectrograph Camera (HFOSC). he photometric monitoring of SN 2004et, in Bessell UBVRI filters , began on 2004 September 29, soon after its discovery, and continued until 2006 March 16. The...
Article
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We present optical spectra of 45 intermediate mass Herbig Ae/Be stars. Together with the multi-epoch spectroscopic and photometric data compiled for a large sample of these stars and ages estimated for individual stars by using pre-main sequence evolutionary tracks, we have studied the evolution of emission line activity in them. We find that, on a...
Article
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We present optical photometry and spectroscopy of the type IIP supernova SN 2004et that occurred in the nearby galaxy NGC 6946. The observations span a time range of 8 days to 541 days after explosion. The late time bolometric luminosity and the H$\alpha$ luminosity in the nebular phase indicate that $0.06\pm0.02{M_\odot}$ of $^{56}$Ni was synthesi...
Article
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Different approaches for automated spectral classification are critically reviewed. We describe in detail ANN based methods which are very efficient in quick handling of the large volumes of data generated by different surveys. We summarize the application of ANN in various surveys covering UV, visual and IR spectral regions and the accuracies obta...
Article
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With a view to investigate variations in parameters of coronal emission lines over a large range of radial distance from the limb, raster scans were made with sufficiently long exposure times on several days during September – October 2003. An analysis of the data shows that (i) in most of the coronal structures, the FWHM of the Fe xiv 5303 line de...
Article
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We have obtained spectroscopic observations in coronal emission lines by choosing two lines simultaneously, one [Fe x] 6374 Å and the other [Fe xi] 7892 Å or [Fe xiii] 10747 Å or [Fe xiv] 5303 Å. We found that in 95 per cent of the coronal loops observed in 6374 Å, the FWHM of the emission line increases with height above the limb irrespective of t...
Article
We present spectroscopic observations in the region of H alpha and Li I lines of the weak emission T Tauri star V410 Tau obtained over 1999/2000, 2002/2003 and 2003/2004 seasons. The emission strength showed rotational modulation during the 1999/2000 season in such a way that the emis- sion strength is maximum at light minimum and vice versa. This...