Harinder P. Singh
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View article: Unveiling the Variability and Chemical Composition of AL Col
Unveiling the Variability and Chemical Composition of AL Col Open
In this study, we present analysis of TESS photometry, spectral energy distribution (SED), high-resolution spectroscopy, and spot modeling of the α2 CVn-type star AL Col (HD 46462). The primary objective is to determine its fundamental phy…
View article: Extraction of Physical Parameters of RRab Variables Using Neural Network Based Interpolator
Extraction of Physical Parameters of RRab Variables Using Neural Network Based Interpolator Open
Determining the physical parameters of pulsating variable stars such as RR Lyrae is essential for understanding their internal structure, pulsation mechanisms, and evolutionary state. In this study, we present a machine learning framework …
View article: Physical parameters of stars in NGC 6397 using ANN-based interpolation and full spectrum fitting
Physical parameters of stars in NGC 6397 using ANN-based interpolation and full spectrum fitting Open
View article: A theoretical framework for BL Her stars
A theoretical framework for BL Her stars Open
Context. The upcoming Rubin-LSST is expected to revolutionize the field of classical pulsators by offering well-sampled multi-epoch photometric data in multiple wavelengths. Type II Cepheids (T2Cs) exhibit weak or negligible metallicity de…
View article: A theoretical framework for BL Her stars
A theoretical framework for BL Her stars Open
Context. In the era of precision stellar astrophysics, classical pulsating stars play a crucial role in determinations of the cosmological distance scale thanks to their period-luminosity (PL) relations. Therefore, it is important to const…
View article: A theoretical framework for BL Her stars IV. New period-luminosity relations in the Rubin-LSST filters
A theoretical framework for BL Her stars IV. New period-luminosity relations in the Rubin-LSST filters Open
We present new theoretical light curves in the Rubin-LSST filters for a fine grid of BL Her models computed using MESA-RSP. We also derive new theoretical period-luminosity (PL) and period-Wesenheit (PW) relations in the Rubin-LSST filters…
View article: A theoretical framework for BL Her stars III. A case study: Robust light curve optimisation in the LMC
A theoretical framework for BL Her stars III. A case study: Robust light curve optimisation in the LMC Open
We carry out an extensive light curve comparison of BL Her stars using observations from Gaia DR3 and stellar pulsation models computed using MESA-RSP with the goal to obtain the best-matched modeled-observed pairs for BL Her stars in the …
View article: Colour-Based Disentangling of Mira Variables and Ultra-Cool Dwarfs
Colour-Based Disentangling of Mira Variables and Ultra-Cool Dwarfs Open
Despite having different astronomical characteristics, the studies of mira variables and ultra-cool dwarfs frequently show similar red colors, which could cause leading to photometric misclassification. This study uses photometric data fro…
View article: Low-mass Stellar and Substellar Content of the Young Cluster Berkeley 59
Low-mass Stellar and Substellar Content of the Young Cluster Berkeley 59 Open
We present a multiwavelength analysis of the young star cluster Berkeley 59, based on Gaia data and deep IR observations with the 3.58 m Telescopio Nazionale Galileo and Spitzer space telescope. The mean proper motion of the cluster is fou…
View article: Low-mass stellar and substellar content of the young cluster Berkeley 59
Low-mass stellar and substellar content of the young cluster Berkeley 59 Open
We present a multi-wavelength analysis of the young star cluster Berkeley 59 (Be 59) based on the $Gaia$ data and deep infrared (IR) observations with the 3.58-m Telescopio Nazionale Galileo and $Spitzer$ space telescope. The mean proper m…
View article: Multiwavelength photometric study of RR lyrae variables in the globular cluster NGC 5272 (Messier 3)
Multiwavelength photometric study of RR lyrae variables in the globular cluster NGC 5272 (Messier 3) Open
We present a comprehensive photometric study of RR Lyrae stars in the M3 globular cluster, utilizing a vast data set of 3140 optical (UBVRI) CCD images spanning 35 yr from astronomical data archives. We have successfully identified previou…
View article: Stellar Variability and Distance Indicators in the Near-infrared in Nearby Galaxies. I. RR Lyrae and Anomalous Cepheids in Draco Dwarf Spheroidal
Stellar Variability and Distance Indicators in the Near-infrared in Nearby Galaxies. I. RR Lyrae and Anomalous Cepheids in Draco Dwarf Spheroidal Open
The Draco Dwarf spheroidal (dSph) galaxy is one of the nearest and the most dark-matter-dominated satellites of the Milky Way. We obtained multiepoch near-infrared (NIR, JHK s ) observations of the central region of Draco dSph covering a s…
View article: Stellar Variability and Distance Indicators in the Near-infrared in Nearby Galaxies. I. RR Lyrae and Anomalous Cepheids in Draco dwarf spheroidal
Stellar Variability and Distance Indicators in the Near-infrared in Nearby Galaxies. I. RR Lyrae and Anomalous Cepheids in Draco dwarf spheroidal Open
Draco dwarf Spheroidal galaxy (dSph) is one of the nearest and the most dark matter dominated satellites of the Milky Way. We obtained multi-epoch near-infrared (NIR, $JHK_s$) observations of the central region of Draco dSph covering a sky…
View article: A theoretical framework for BL Her stars
A theoretical framework for BL Her stars Open
Context. In the era of the Hubble tension, it is crucial to obtain a precise calibration of the period-luminosity (PL) relations of classical pulsators. Type II Cepheids (T2Cs; often exhibiting negligible or weak metallicity dependence on …
View article: A theoretical framework for BL Her stars -- II. New period-luminosity relations in the Gaia passbands
A theoretical framework for BL Her stars -- II. New period-luminosity relations in the Gaia passbands Open
We present new theoretical period-luminosity (PL) and period-Wesenheit (PW) relations for a fine grid of convective BL Her, the shortest period T2Cs, models computed using MESA-RSP and compare our results with the empirical relations from …
View article: High-resolution Spectroscopic Metallicities of Milky Way Cepheid Standards and their impact on the Leavitt Law and the Hubble constant
High-resolution Spectroscopic Metallicities of Milky Way Cepheid Standards and their impact on the Leavitt Law and the Hubble constant Open
Milky Way Cepheid variables with accurate {\it Hubble Space Telescope} photometry have been established as standards for primary calibration of the cosmic distance ladder to achieve a percent-level determination of the Hubble constant ($H_…
View article: High-resolution Spectroscopic Metallicities of Milky Way Cepheid Standards and Their Impact on the Leavitt Law and the Hubble Constant
High-resolution Spectroscopic Metallicities of Milky Way Cepheid Standards and Their Impact on the Leavitt Law and the Hubble Constant Open
Milky Way Cepheid variables with accurate Hubble Space Telescope photometry have been established as standards for primary calibration of the cosmic distance ladder to achieve a percent-level determination of the Hubble constant ( H 0 ). T…
View article: Predicting light curves of RR Lyrae variables using artificial neural network based interpolation of a grid of pulsation models
Predicting light curves of RR Lyrae variables using artificial neural network based interpolation of a grid of pulsation models Open
We present a new technique to generate the light curves of RRab stars in different photometric bands (I and V bands) using artificial neural networks (ANN). A pre-computed grid of models was used to train the ANN, and the architecture was …
View article: Predicting light curves of RR Lyrae variables using artificial neural network based interpolation of a grid of pulsation models
Predicting light curves of RR Lyrae variables using artificial neural network based interpolation of a grid of pulsation models Open
We present a new technique to generate the light curves of RRab stars in different photometric bands ($I$ and $V$ bands) using Artificial Neural Networks (ANN). A pre-computed grid of models was used to train the ANN, and the architecture …
View article: Precise Empirical Determination of Metallicity Dependence of Near-infrared Period-Luminosity Relations for RR Lyrae Variables
Precise Empirical Determination of Metallicity Dependence of Near-infrared Period-Luminosity Relations for RR Lyrae Variables Open
RR Lyrae variables are excellent population II distance indicators thanks to their well-defined period-luminosity relations (PLRs) at infrared wavelengths. We present results of near-infrared (NIR) monitoring of Galactic globular clusters …
View article: Precise Empirical Determination of Metallicity Dependence of Near-infrared Period–Luminosity Relations for RR Lyrae Variables
Precise Empirical Determination of Metallicity Dependence of Near-infrared Period–Luminosity Relations for RR Lyrae Variables Open
RR Lyrae variables are excellent Population II distance indicators thanks to their well-defined period–luminosity relations (PLRs) at infrared wavelengths. We present results of near-infrared (NIR) monitoring of Galactic globular clusters …
View article: Near-infrared observations of RR Lyrae and Type II Cepheid variables in the metal-rich bulge globular cluster NGC 6441
Near-infrared observations of RR Lyrae and Type II Cepheid variables in the metal-rich bulge globular cluster NGC 6441 Open
Context. NGC 6441 is a bulge globular cluster (GC) with an unusual horizontal branch morphology and a rich population of RR Lyrae (RRL) and Type II Cepheid (T2C) variables that is unexpected for its relatively high metallicity. Aims. Our g…
View article: Extra-tidal star candidates in globular clusters of the Sagittarius dwarf spheroidal galaxy
Extra-tidal star candidates in globular clusters of the Sagittarius dwarf spheroidal galaxy Open
Context. Globular clusters (GCs) associated with the Sagittarius dwarf spheroidal galaxy (Sgr dSph) have evolved under the gravitational potential of both Sgr dSph and the Milky Way. The effects of these potentials are most pronounced in t…
View article: Optical Characterization of Two Cataclysmic Variables: RBS 0490 and SDSS J075939.79+191417.3
Optical Characterization of Two Cataclysmic Variables: RBS 0490 and SDSS J075939.79+191417.3 Open
We present optical photometric and spectroscopic observations of two cataclysmic variables (CVs), namely RBS 0490 and SDSS J075939.79+191417.3. The optical variations of RBS 0490 have been found to occur with a period of 1.689 ± 0.001 hr, …
View article: First detection of a magnetic field in low-luminosity B[e] stars
First detection of a magnetic field in low-luminosity B[e] stars Open
We report the first detection of the magnetic field in a star of FS CMa type, a subgroup of objects characterized by the B[e] phenomenon. The split of magnetically sensitive lines in IRAS 17449+2320 determines the magnetic field modulus of…
View article: The Indo‐US Library of Coude Feed Stellar Spectra
The Indo‐US Library of Coude Feed Stellar Spectra Open
We have obtained spectra for 1273 stars using the 0.9 m coudé feed telescope at Kitt Peak National Observatory. This telescope feeds the coudé spectrograph of the 2.1 m telescope. The spectra have been obtained with the no. 5 camera of the…
View article: APOGEE discovery of a chemically atypical star disrupted from NGC 6723 and captured by the Milky Way bulge
APOGEE discovery of a chemically atypical star disrupted from NGC 6723 and captured by the Milky Way bulge Open
The central (‘bulge’) region of the Milky Way is teeming with a significant fraction of mildly metal-deficient stars with atmospheres that are strongly enriched in cyanogen ( 12 C 14 N). Some of these objects, which are also known as nitro…
View article: A theoretical framework for BL Her stars – I. Effect of metallicity and convection parameters on period–luminosity and period–radius relations
A theoretical framework for BL Her stars – I. Effect of metallicity and convection parameters on period–luminosity and period–radius relations Open
We present a new grid of convective BL Herculis models using the state-of-the-art 1D non-linear radial stellar pulsation tool mesa-rsp. We investigate the impact of metallicity and four sets of different convection parameters on multiwavel…
View article: Extra-tidal star candidates around the Galactic globular clusters NGC 2808, NGC 6266 and NGC 6397 with Gaia DR2 astrometry
Extra-tidal star candidates around the Galactic globular clusters NGC 2808, NGC 6266 and NGC 6397 with Gaia DR2 astrometry Open
Context. Extra-tidal stars are those that lie outside the tidal radius of a cluster due to internal processes or external forces acting on it. The presence and spatial distribution of these stars can give us insights into the past evolutio…
View article: A study of the stellar photosphere-hydrogen ionisation front interaction in pulsating variables using period-color relations
A study of the stellar photosphere-hydrogen ionisation front interaction in pulsating variables using period-color relations Open
Period-color (PC) relations may be used to study the interaction of the stellar photosphere and the hydrogen ionization front (HIF). RR Lyraes (RRLs) and long period classical Cepheids (P > 10d) have been found to exhibit different PC beha…