arXiv subjects

Ayush Moharana

Publications and source records attributed to Ayush Moharana.

10 recordsLinked to original sources

arXiv2026

UX Men: Detached Eclipsing Binary as a Benchmark Candidate

We present ultra-precise fundamental parameters for the detached eclipsing binary UX Men based on 31 TESS sectors ($\sim$882 d) and radial velocities from HARPS, FEROS, CORALIE, and UCLES. The light curves were detrended for spot-induced variability and modelled independently with JKTEBOP and ALLESFITTER, while radial velocities were extracted via TODCOR and fitted with a Keplerian orbit. Spectral disentangling yielded individual component spectra analysed with iSpec to determine $T_{\rm eff}$ and $\mathrm{[M/H]}$. Multi-band photometry was used to determine the fluxes, flux ratios and ultimately to measure photometric $T_{\rm eff}$. We obtain the masses $M_{\rm A}$ = $1.2300 \pm{0.0012}$ M$_{\odot}$, $M_{\rm B}$ = $1.1946\pm{0.0012}$ M$_{\odot}$ and radii $R_{\rm A}$ = $1.3605\pm{0.0031}$ R$_{\odot}$, $R_{\rm B}$ = $1.2801\pm{0.0069}$ R$_{\odot}$ with sub-percent precision. Uncertainties were found to be dominated by systematic effects coming from (weak) stellar activity. $T_{\rm eff,A}$ = $6302\pm{77}$, $T_{\rm eff,B}$ = $6292\pm65$ \& Metallicity estimates are $[M/H]_{\rm A} = 0.02\pm{0.13}$ dex and $[M/H]_{\rm B}= 0.07\pm{0.10}$ dex. Isochrone fitting yields a consistent age of $τ$ = $2.75\pm{0.13}$ Gyr. The system exhibits a $\sim$ 673-day periodicity in eclipse-timing variations, likely due to stellar activity, with no evidence for a third body. Results are independent of the modelling code used, but without proper treatment of activity-induced systematics the uncertainties would be underestimated. UX Men is a high-precision benchmark binary providing stringent tests of stellar models and a robust calibration source for PLATO. Expanding the sample of well-characterised detached eclipsing binaries will strengthen the empirical foundations for stellar physics and the calibration of future photometric missions

astro-ph.SR↗

arXiv2026

Multiplicity of Cool Stars and their Evolution

Making up a sizeable portion of the galactic census, stellar multiples are experiencing a renaissance. Enabling the study of multiple strands of the study of cool stars, stellar multiples have been found and characterised in great numbers by the missions of the last decade, allowing the exploration of stellar parameters and populations, observation of stellar interactions, studies into stellar formation and evolution, and characterisation of circumbinary systems. This exciting explosion of science is only set to continue, with future missions set to offer even further insights into the topic. Within these proceedings we will summarise the presentations and discussions on cool stellar multiplicity within our splinter sessions at the 23rd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, as we examine the present state of the field and look to what the future may bring.

astro-ph.SR↗

arXiv2026

Detached eclipsing binary star science in the 2040s

Detached eclipsing binary stars (DEBS) are currently the best source of accurate and precise fundamental stellar parameters. This makes DEBS crucial targets for constraining the impact of various physical processes on stellar structure and evolution. Long-period binaries are particularly interesting because their separation minimises interactions between the components. This makes long-period binaries more comparable to single stars. However, the current sample of DEBS with high precision stellar parameters are dominated by short-period systems (e.g. ~90% of the Gaia DR3 eclipsing binaries have periods < 5 days). Facilities capable of performing detailed studies of long-period DEBS will be essential to further improve our understanding of stellar structure and evolution. Such facilities would need to be able to obtain spectroscopic observations of more distant objects at high resolution and cadence. 2-8m class telescopes with echelle spectrographs and an ability to monitor a large sample of stars would be required.

astro-ph.IM↗

arXiv2024

Adding TESS to CRÉME. Light curves and masses of 300+ eclipsing binaries

The Comprehensive Research with Echelles on the Most interesting Eclipsing binaries (CRÉME) projects was aimed to collect high-resolutions spectra of about 380 detached eclipsing binaries (DEBs), which mostly do not have literature RV data. From this vast observational material we were able to estimate masses of components of 325 double-lined system. Since the launch of the TESS mission we have been collecting 2-min cadence photometry for the CRÉME targets through successful GI proposals. As by Sector 85, we obtained data for $>$330 of them. We are thus now in the process of comprehensively analyzing our targets. This paper presents the recent status of the CRÉME project and its space photometry counterpart, and describes several sub-projects within CRÉME that focus on specific classes of targets.

astro-ph.SR↗

arXiv2024

Formation of Compact Hierarchical Triples

Compact hierarchical triples (CHTs) are triple stars where the tertiary is in an orbit of a period less than 1000 d. They were thought to be rare but we are discovering more of these systems recently, thanks to space-based missions like TESS, Kepler, and GAIA. In this work, we use orbital parameters obtained from these missions to constrain the formation process of CHTs. We also use spectroscopic and systemic parameters from our work, and the literature to understand the effects of metallicity and dynamics on the formation processes.

astro-ph.SR↗

arXiv2024

Spectroscopy of Eclipsing Compact Hierarchical Triples I

Eclipsing Compact Hierarchical Triples (ECHTs) are systems with the tertiary star orbiting an eclipsing binary (EB) in an orbit of fewer than 1000 days. In a CHT, all three stars exist in a space less than 5 AU in separation. A low-mass CHT is an interesting case to understand multiple star and planet formation at such small scales. In this study, we combine spectroscopy and photometry to estimate the orbital, stellar and atmospheric parameters of stars in a sample of CHTs. Using the complete set of parameters we aim to constrain the metallicity and age of the systems. We use time-series spectroscopy to obtain radial velocities (RVs) and disentangled spectra. Using RV modelling, EB light curve modelling, and spectral analysis, we estimated the metallicities and temperatures. Using isochrone fitting, we constrain the ages of the system. We then combine observations of masses, outer eccentricities (e_2), orbital periods and age estimates of the systems from the literature. We compare the distributions of e_2, and tertiary mass ratio, q_3 = M_3/(M_1+M_2), for three different metallicity ranges and two ranges of age. We estimate masses, radii, temperatures, metallicities and age of 12 stars in 4 CHTs. The CHT CD-32 6459 shows signs of von Zeipel-Lidov-Kozai oscillations while CD-62 1257 can evolve to form a triple common envelope. The rest of the CHTs are old and have an M-dwarf tertiary. We find that the q_3 distribution for CHTs with sub-solar metallicity has a uniform distribution but the systems with solar and above-solar metallicity peak between 0.5 and 1. When dividing them according to their ages, we found the q_3 of old systems around 0.5. The eccentricity e_2 favours a value around 0.3 irrespective of metallicity or age. The distributions are biased by the lack of observations and observing methods and therefore call for more observations of low-mass CHT.

astro-ph.SR↗

arXiv2023

Solaris photometric survey: Search for circumbinary companions using eclipse timing variations

Eclipse timing variations (ETV) have been a successful tool for detecting circumbinary companions to eclipsing binaries (EB). While TESS and Kepler have been prolific for ETV searches, they sometimes can be limited by time and sky coverage which can be addressed by specialised ground-based ETV surveys. We present the initial results from the Solaris photometric survey which uses four 0.5m robotic telescopes in the southern hemisphere to look for circumbinary companions. We present the method of light curve extraction, detrending, and EB modelling using the observations from the Solaris network. Using these light curves we extract precise eclipse timing for 7 EB and look for companions using a Lomb-Scargle periodogram search. We find two possible periodic signals for the target GSC 08814-01026. With the system having strong activity, we check for the feasibility of orbital solutions at these two periods. We find that the 245 +/- 1 d period is due to an M-dwarf mass companion. This makes GSC 08814-01026 a candidate compact hierarchical triple system. The other periodic signal at 146 +/- 1 d is an artefact of stellar activity.

astro-ph.SR↗

arXiv2023

Detached Eclipsing Binaries in Compact Hierarchical Triples: Triple-lined systems BD+44 2258 and KIC 06525196

Compact Hierarchical Triples (CHT) are systems with the tertiary star orbiting the inner binary in an orbit shorter than 1000 days. CHT with an eclipsing binary as its inner binary can help us extract a multitude of information about all three stars in the system. In this study, we use independent observational techniques to estimate the orbital, stellar, and atmospheric parameters of two triple-lined CHT: BD+442258 and KIC06525196. We find that the masses of stars in BD+442258 are $1.011\pm0.029 M_{\odot}$, $0.941\pm0.033 M_{\odot}$, and $0.907\pm0.065 M_{\odot}$ while in KIC06525196 the estimated masses are $1.0351\pm0.0055 M_{\odot}$, $0.9712\pm0.0039 M_{\odot}$, and $0.777\pm0.012 M_{\odot}$. Using spectral disentangling, we obtained individual spectra of all the stars and combined them with light curve modeling to obtain radii, metallicities, and temperatures. Using stellar evolution models from MESA, we constrain the log(age) of BD+442258 to be 9.89 and 9.49 for KIC06525196. Two stars in BD+442258 are found to be sub-giants while all three stars in KIC06525196 are main-sequence stars. We constrain the mutual inclinations to certain angles for BD+442258 and KIC06525196 using numerical integration. Integrating with tidal interaction schemes and stellar evolution models, we find that KIC06525196 is a stable system. But the inner binary of BD+442258 merges within 550 Myrs. The time of this merger is affected by the orientation of the tertiary, even rushing the collapse by 100 Myrs when the mutual inclination is close to 90 degrees.

astro-ph.SR↗

arXiv2023

Evolution and Dynamics of Tight Triple Systems

Tight Triple Systems have stars in a hierarchical configuration with a third star orbiting the inner binary with a period of fewer than 1000 days. Such systems are important for understanding the formation and evolution of stars in multiple systems. Having a detached eclipsing binary (DEB) as one of its components allows us to obtain precise stellar and orbital parameters of these systems. We discuss the process to obtain accurate parameters of these systems using high-resolution spectroscopy, radial velocity measurements, and precise space-based photometry. This enables us to have a 3D geometrical picture as well as the metallicity, age, and evolutionary status of these systems.

astro-ph.SR↗

arXiv2020

Ultraviolet Imaging Telescope (UVIT) observation of the Galactic Globular Cluster NGC 7492

We present detailed photometric observations of the Galactic globular cluster NGC 7492 using the data obtained with two far-ultraviolet (FUV: 1300 - 1800 Å) and three near-ultraviolet (NUV: 2000 - 3000 Å) filters of Ultraviolet Imaging Telescope (UVIT) on-board the \textit{AstroSat} satellite. We confirmed the cluster membership of the extracted sources using GAIA data release 2 (Gaia DR2) proper motion data. We have used color-magnitude diagrams (CMDs) using UVIT and GAIA filters to separate out different evolutionary stages of the stars present in the cluster. We have identified a new extreme horizontal branch (EHB) star at the core of the cluster using UV and UV-optical CMDs. The estimated distance-modulus of the cluster is $16.95\pm0.05$ obtained by fitting BaSTI isochrones with cluster parameters, $[Fe/H] = -1.8$ dex and age $= 12.0$ Gyr on the V $-$ I vs V CMD. Interestingly, only the EHB star and blue horizontal branch stars (BHBs) among the UV-bright hot sources are detected in FUV filters of UVIT. We have derived the effective temperature of BHBs using color-temperature relation and spectral energy distributions (SEDs) of multi-band filters, which are in the range from 8,000 K to 10,500 K. We find a variation of He abundance of BHBs by fitting the BaSTI ZAHB. The range in the He abundance of the BHBs corresponding to the best fit isochrones is 0.247 to 0.350. We have estimated various physical parameters of the newly identified EHB star in the cluster using SED fit and post-HB evolutionary tracks. We have studied the radial distribution of all the sources of the cluster detected in UVIT. The sources detected in FUV filters extend beyond the half light radius (1.15$'$) of the cluster, whereas the sources detected in NUV filters extend beyond the tidal radius (9.2$'$) of the cluster.

astro-ph.GA↗