Arpita Roy
A5040040199- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Spectroscopy and Laser Applications
- Advanced Fiber Laser Technologies
- Calibration and Measurement Techniques
- Galaxies: Formation, Evolution, Phenomena
- Atmospheric Ozone and Climate
- Space Exploration and Technology
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Scientific Research and Discoveries
- Astrophysical Phenomena and Observations
- Coal Properties and Utilization
- Planetary Science and Exploration
- Advanced Frequency and Time Standards
- Particle Accelerators and Free-Electron Lasers
- Astronomical and nuclear sciences
- Nanoparticles: synthesis and applications
- Magnetic confinement fusion research
- High-pressure geophysics and materials
Berkeley College
2025
University of California, Berkeley
2025
Space Telescope Science Institute
2020-2024
Johns Hopkins University
2021-2024
Sharda University
2022-2024
Indian Institute of Engineering Science and Technology, Shibpur
2024
Galgotias University
2023
Pennsylvania State University
2012-2022
Macquarie University
2018-2022
NSF’s NOIRLab
2022
The M dwarf star Gliese 581 is believed to host four planets, including one (GJ 581d) near the habitable zone that could possibly support liquid water on its surface if it a rocky planet. detection of another habitable-zone planet--GJ 581g--is disputed, as significance depends eccentricity assumed for d. Analyzing stellar activity using Hα line, we measure rotation period 130 ± 2 days and correlation modulation with radial velocity. Correcting greatly diminishes signal GJ 581d (to 1.5...
The Habitable-Zone Planet Finder is a stabilized, fiber-fed, NIR spectrograph being built for the 10m Hobby- Eberly telescope (HET) that will be capable of discovering low mass planets around M dwarfs. optical design HPF white pupil layout in vacuum cryostat cooled to 180 K. uses gold-coated mirrors, mosaic echelle grating, and single Teledyne Hawaii-2RG (H2RG) detector with 1.7-micron cutoff covering parts information rich z, Y J bands at spectral resolution R∼50,000. unique HET requires...
We have developed an optical design for a high resolution spectrograph in response to NASA's call extreme precision Doppler spectrometer (EPDS) the WIYN telescope. Our instrument covers wavelength range of 380 930 nm using single detector and with 100,000. To deliver most stable spectrum, we avoid use image slicer, favor large (195 mm diameter) beam footprint on 1x2 mosaic R4 Echelle grating. The is based classic white pupil layout, parabolic mirror that used as main transfer collimator....
Insufficient instrument thermo-mechanical stability is one of the many roadblocks for achieving 10cm/s Doppler radial velocity (RV) precision, precision needed to detect Earth-twins orbiting Solar-type stars. Highly temperature and pressure stabilized spectrographs allow us better calibrate out instrumental drifts, thereby helping in distinguishing noise from astrophysical stellar signals. We present design performance Environmental Control System (ECS) Habitable-zone Planet Finder (HPF), a...
Using the Keck Planet Imager and Characterizer (KPIC), we obtained high-resolution (R$\sim$35,000) $K$-band spectra of four planets orbiting HR 8799. We clearly detected \water{} CO in atmospheres 8799 c, d, e, tentatively a combination b. These are most challenging directly imaged exoplanets that have been observed at high spectral resolution to date when considering both their angular separations flux ratios. developed forward modeling framework allows us jointly fit diffracted starlight...
Abstract The warm Neptune GJ 3470b transits a nearby ( d = 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two with the newly commissioned NEID spectrometer on WIYN 3.5 m Telescope at Kitt Peak Observatory, we model classical Rossiter–McLaughlin effect, yielding sky-projected obliquity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>98</mml:mn>...
Abstract The Near-Infrared Imager and Slitless Spectrograph (NIRISS) is the science module of Canadian-built Fine Guidance Sensor onboard James Webb Space Telescope (JWST). NIRISS has four observing modes: (1) broadband imaging featuring seven eight NIRCam filters, (2) wide-field slitless spectroscopy at a resolving power ∼150 between 0.8 2.2 μ m, (3) single-object cross-dispersed (SOSS) enabling simultaneous wavelength coverage 0.6 2.8 m R ∼ 700, mode optimized for exoplanet relatively...
Abstract We present the discovery of TOI-5205b, a transiting Jovian planet orbiting solar metallicity M4V star, which was discovered using Transiting Exoplanet Survey Satellite photometry and then confirmed combination precise radial velocities, ground-based photometry, spectra, speckle imaging. TOI-5205b has one highest mass ratios for M-dwarf planets, with ratio almost 0.3%, as it orbits host star that is just 0.392 ± 0.015 M ⊙ . Its planetary radius 1.03 0.03 R J , while 1.08 0.06...
The Near Infrared Imager and Slitless Spectrograph instrument (NIRISS) is the Canadian Space Agency (CSA) contribution to suite of four science instruments JWST. As one three NIRISS observing modes, Single Object Spectroscopy (SOSS) mode tailor-made undertake time-series observations exoplanets perform transit spectroscopy. SOSS permits point sources between 0.6 2.8 um at a resolving power 650 1.25 using slit-less cross-dispersing grism while its defocussing cylindrical lens enables targets...
Abstract We confirm TOI-4201 b as a transiting Jovian-mass planet orbiting an early M dwarf discovered by the Transiting Exoplanet Survey Satellite. Using ground-based photometry and precise radial velocities from NEID Planet Finder Spectrograph, we measure mass of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>2.59</mml:mn> </mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.06</mml:mn> <mml:mo>+</mml:mo> <mml:mn>0.07</mml:mn>...
Abstract Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity (RV) data are needed for definitive confirmation. Here we present RV follow-up observations 28 M and K with candidate astrometric which led confirmation two systems, Gaia-4b Gaia-5b, identification five systems that single lined require additional confirm as refutation 21 stellar binaries. a massive planet ( = 11.8 ± 0.7 J ) in P 571.3 1.4 day...
Abstract We present spectral observations of the multiplanet host TOI-1694 during transit TOI-1694b, a 26.1 M ⊕ hot Neptune with 3.77 day orbit. By analyzing radial velocities obtained from Keck Planet Finder, we modeled Rossiter–McLaughlin effect and constrained sky-projected obliquity to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>9</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> <mml:msup>...
We have used high-resolution spectroscopy to observe the Kepler-16 eclipsing binary as a double-lined system, and measure precise radial velocities for both stellar components. These yield dynamical mass-ratio of q=0.2994+-0.0031. When combined with inclination, i=90.3401+0.0016-0.0019 deg, measured from Kepler photometric data by Doyle et al. 2011, we derive masses components M_A=0.654+-0.017 M_sun M_B=0.1959+-0.0031 M_sun, precision 2.5% 1.5% respectively. Our results confirm at ~2% level...
We validate the discovery of a 2 Earth radii sub-Neptune-size planet around nearby high proper motion M2.5-dwarf G 9-40 (EPIC 212048748), using high-precision near-infrared (NIR) radial velocity (RV) observations with Habitable-zone Planet Finder (HPF), precision diffuser-assisted ground-based photometry custom narrow-band photometric filter, and adaptive optics imaging. At distance $d=27.9\mathrm{pc}$, 9-40b is second closest transiting discovered by K2 to date. The planet's large transit...
Abstract LTT 1445 is a hierarchical triple M-dwarf star system located at distance of 6.86 pc. The primary 1445A (0.257 M ⊙ ) known to host the transiting planet 1445Ab with an orbital period 5.36 days, making it second-closest exoplanet system, and closest one for which dwarf. Using Transiting Exoplanet Survey Satellite data, we present discovery second in 3.12 days. We combine radial-velocity measurements obtained from five spectrographs, Echelle Spectrograph Rocky Exoplanets Stable...
Abstract A benchmark brown dwarf (BD) is a BD whose properties (e.g., mass and chemical composition) are precisely independently measured. Benchmark BDs valuable in testing theoretical evolutionary tracks, spectral synthesis, atmospheric retrievals for substellar objects. Here, we report results of retrieval on synthetic spectrum BD, HR 7672 B, with petitRADTRANS . First, test the framework PHOENIX BT-Settl solar composition. We show that retrieved C O abundances consistent values, but C/O...
We present spectroscopic measurements of the Rossiter-McLaughlin effect for WASP-148b, only known hot Jupiter with a nearby warm-Jupiter companion, from WIYN/NEID and Keck/HIRES instruments. This is one first scientific results reported newly commissioned NEID spectrograph, as well second obliquity constraint system close-in after WASP-47. WASP-148b consistent being in alignment sky-projected spin axis host star, $\lambda=-8^{\circ}.2^{{+8^{\circ}.7}}_{-9^{\circ}.7}$. The low observed...
We confirm the planetary nature of two gas giants discovered by TESS to transit M dwarfs. TOI-3714 ($V=15.24,~J=11.74$) is an M2 dwarf hosting a hot Jupiter ($M_p=0.70 \pm 0.03~\mathrm{M_J}$ and $R_p=1.01 0.03~\mathrm{R_J}$) on orbital period $2.154849 0.000001$ days with resolved white companion. TOI-3629 ($V=14.63,~J=11.42$) M1 ($M_p=0.26 0.02~\mathrm{M_J}$ $R_p=0.74 0.02~\mathrm{R_J}$) $3.936551_{-0.000006}^{+0.000005}$ days. characterize each transiting companion using combination...
Abstract The Kepler and TESS missions have demonstrated that planets are ubiquitous. However, the success of these heavily depends on ground-based radial velocity (RV) surveys, which combined with transit photometry can yield bulk densities orbital properties. While most host stars too faint for detailed follow-up observations, is detecting orbiting nearby bright more amenable to RV characterization. Here, we introduce TESS-Keck Survey (TKS), an program using ∼100 nights Keck/HIRES study...
Abstract We present a radial velocity (RV) analysis of TOI-1136, bright Transiting Exoplanet Survey Satellite (TESS) system with six confirmed transiting planets, and seventh single-transiting planet candidate. All planets in the are amenable to transmission spectroscopy, making TOI-1136 one best targets for intra-system comparison exoplanet atmospheres. is young (∼700 Myr), exhibits transit timing variations (TTVs). The youth contributes high stellar variability on order 50 m s −1 , much...
Abstract Giant exoplanets orbiting close to their host stars are unlikely have formed in present configurations 1 . These ‘hot Jupiter’ planets instead thought migrated inward from beyond the ice line and several viable migration channels been proposed, including eccentricity excitation through angular-momentum exchange with a third body followed by tidally driven orbital circularization 2,3 The discovery of extremely eccentric ( e = 0.93) giant exoplanet HD 80606 b (ref. 4 ) provided...
Abstract The degree of alignment between a star’s spin axis and the orbital plane its planets (the stellar obliquity) is related to interesting poorly understood processes that occur during planet formation evolution. Hot Jupiters orbiting hot stars (≳6250 K) display wide range obliquities, while similar cool are preferentially aligned. Tidal dissipation expected be more rapid in with thick convective envelopes, potentially explaining this trend. Evolved provide an opportunity test damping...
Abstract TOI-6255 b (GJ 4256) is an Earth-sized planet (1.079 ± 0.065 R ⊕ ) with orbital period of only 5.7 hr. With the newly commissioned Keck Planet Finder and CARMENES spectrographs, we determine planet’s mass to be 1.44 0.14 M . The just outside Roche limit, P orb / = 1.13 0.10. strong tidal force likely deforms into a triaxial ellipsoid long axis that ∼10% longer than short axis. Assuming reduced stellar quality factor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...