Sarbani Basu
A5085536840- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Ionosphere and magnetosphere dynamics
- Astrophysics and Star Formation Studies
- Geomagnetism and Paleomagnetism Studies
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Gamma-ray bursts and supernovae
- Earthquake Detection and Analysis
- Solar Radiation and Photovoltaics
- Astronomical Observations and Instrumentation
- Atmospheric Ozone and Climate
- History and Developments in Astronomy
- Scientific Research and Discoveries
- Geological and Geophysical Studies
- Microwave Engineering and Waveguides
- Neutrino Physics Research
- Meteorological Phenomena and Simulations
- Space Exploration and Technology
- Global Energy and Sustainability Research
- Magnetic confinement fusion research
- Radio Frequency Integrated Circuit Design
- Advanced Thermodynamics and Statistical Mechanics
Yale University
2015-2024
Western University
2000-2022
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Institute for Advanced Study
1998-2018
The Ohio State University
2018
Boston College
1998-2018
National Yang Ming Chiao Tung University
2018
Marcus (United States)
2018
Aarhus University
1995-2015
The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using original SDSS wide-field imager, and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution novel interferometer. All SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all acquired through 2013 July, 12 (DR12) adding July (including included in previous releases), marking end observing. Relative our public...
Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors thermodynamic radiative properties, on which depend, matter under extreme conditions found in sun. Current are agreement with inferences, suggests, example, that disagreement between predicted observed fluxes neutrinos sun is not caused by errors models. However, GONG data reveal subtle models, such as an excess sound speed just beneath convection...
The splitting of the frequencies global resonant acoustic modes Sun by large-scale flows and rotation permits study variation angular velocity Ω with both radius latitude within turbulent convection zone deeper radiative interior. nearly uninterrupted Doppler imaging observations, provided Solar Oscillations Investigation (SOI) using Michelson Imager (MDI) on Heliospheric Observatory (SOHO) spacecraft positioned at L1 Lagrangian point in continuous sunlight, yield oscillation power spectra...
The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations Milky Way. After a three year observing campaign on 2.5-m Telescope, APOGEE collected half million high resolution (R~22,500), S/N (>100), infrared (1.51-1.70 microns) spectra for 146,000 stars, with time series information via repeat visits to most these stars....
This paper investigates the relative importance of cyclical fluctuations in labor and capital utilization, increasing returns to scale, technology shocks as explanations for procyclical productivity. It exploits intuition that materials inputs do not have variable utilization rates, are likely be used fixed proportions with value added. Therefore, growth is a good measure unobserved changes utilization. Using this shows factor very important, scale about constant, small low correlation...
We calculate accurate solar models and report the detailed time dependences of important quantities. use helioseismology to constrain luminosity evolution Sun discovery semiconvection in evolved that include diffusion. In addition, we compare computed sound speeds with results p-mode observations by BiSON, GOLF, GONG, LOWL, MDI instruments. contrast neutrino predictions from a set eight standard-like four deviant (or deficient) experiments. For helioseismological applications, present...
We construct solar models with the newly calculated radiative opacities from Opacity Project (OP) and recently determined (lower) heavy-element abundances. compare results new predictions of a series that use OPAL opacities, older determinations surface abundances, refinements nuclear reaction rates. For all variations we consider, are constructed newer lower abundances advocated by Asplund et al. disagree much more than estimated measuring errors helioseismological depth convective zone,...
Abstract The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and Extended Baryon Oscillation Spectroscopic (eBOSS). As well as its program, eBOSS contains two major subprograms: Time Domain (TDSS) SPectroscopic IDentification ERosita Sources (SPIDERS). This paper describes first data release from SDSS-IV,...
We report on the masses, sizes, and orbits of planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits 7 revealed by precise Doppler measurements host Based an analysis brightness measurements, along with high-resolution imaging spectroscopy, (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all transiting (41 have FPP under 1%), constrain their sizes masses. Most smaller than three...
We model growth and technology transfer in a world where technologies are specific to particular combinations of inputs. Unlike the usual specification, our does not imply that an improvement one technique for producing given good improves all other techniques good. Technology improvements diffuse slowly across countries, although knowledge spreads instantaneously there no adoption costs. However, even with “Ak” production, implies conditional convergence. This model, appropriate diffusion,...
Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius age, through observationsof normal modes oscillation. The technical requirements for conducting asteroseismology include ultra-high precision measured in photometry parts per million, well nearly continuous time series over weeks to years, cadences rapid enough sample oscillations with periods shortas a few minutes. We report on results from first 43 days observations which unique...
In the Solar system planets' compositions vary with orbital distance, rocky planets in close orbits and lower-density gas giants wider orbits. The detection of close-in giant around other stars was first clue that this pattern is not universal, can change substantially after their formation. Here we report another violation orbit-composition pattern: two orbiting same star distances differing by only 10%, densities a factor 8. One planet likely `super-Earth', whereas more akin to Neptune....
We present revised properties for 196,468 stars observed by the NASA Kepler mission and used in analysis of Quarter 1–16 (Q1–Q16) data to detect characterize transiting planets. The catalog is based on a compilation literature values atmospheric (temperature, surface gravity, metallicity) derived from different observational techniques (photometry, spectroscopy, asteroseismology, exoplanet transits), which were then homogeneously fitted grid Dartmouth stellar isochrones. use broadband...
Rotation is expected to have an important influence on the structure and evolution of stars. However, mechanisms angular momentum transport in stars remain theoretically uncertain very complex take into account stellar models. To achieve a better understanding these processes, we desperately need observational constraints internal rotation stars, which until recently were restricted Sun. In this paper, report detection mixed modes - i.e. that behave both as g core p envelope spectrum early...
We use asteroseismic data obtained by the NASA Kepler Mission to estimate fundamental properties of more than 500 main-sequence and sub-giant stars. Data during first 10 months science operations were used for this work, when these solar-type targets observed one month each in a survey mode. Stellar have been estimated using two global parameters complementary photometric spectroscopic data. Homogeneous sets effective temperatures available entire ensemble from photometry; estimates T_eff...
We present a study of 33 Kepler planet-candidate host stars for which asteroseismic observations have sufficiently high signal-to-noise ratio to allow extraction individual pulsation frequencies. implement new Bayesian scheme that is flexible in its input process oscillation frequencies, combinations them, and average parameters, derive robust fundamental properties these targets. Applying this grids evolutionary models yields stellar with median statistical uncertainties 1.2 per cent...
Mass-loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in the chemical enrichment galaxies. Thanks to recent detection solar-like oscillations G–K giants open clusters with Kepler, we can now directly determine stellar masses for a statistically significant sample old NGC 6791 and 6819. The aim this work constrain integrated RGB mass-loss by comparing average mass clump (RC) that low-luminosity portion [i.e. L≲L(RC)]. Stellar were determined combining...
This paper documents the sixteenth data release (DR16) from Sloan Digital Sky Surveys; fourth and penultimate phase (SDSS-IV). is first of southern hemisphere survey Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new APOGEE-2 North are also included. DR16 notable as final for main cosmological program Extended Baryon Oscillation Spectroscopic Survey (eBOSS), all raw reduced spectra that project released here. includes Time Domain (TDSS) SPectroscopic IDentification...
In addition to its search for extra-solar planets, the NASA Kepler Mission provides exquisite data on stellar oscillations. We report detections of oscillations in 500 solartype stars field view, an ensemble that is large enough allow statistical studies intrinsic properties (such as mass, radius and age) test theories evolution. find distribution observed masses these shows intriguing differences predictions from models synthetic populations Galaxy.
We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius mass, respectively. The results include new asteroseismic solutions four stars confirmed planets (Kepler-4, Kepler-14, Kepler-23 Kepler-25) increase the total number 77. A comparison stellar catalog by Batalha et al. shows that radii subgiants giants obtained from spectroscopic follow-up are systematically too low up a factor 1.5,...
Misaligned Planets Stars with multiple coplanar planets have not been seen to show misalignments between the equatorial plane of star and orbital planets—a diagnostic dynamical history planetary systems. Huber et al. (p. 331 ) analyzed Kepler 56 system, which contains a giant-sized an intermediate-sized planet. The orbits that are close coplanar, but misaligned stellar equator. A third companion in wide orbit, could be another or planet, explain configuration.
We construct updated solar models with different sets of abundances, including the most recent determinations by Asplund et al. The latter work predicts a larger (∼10%) metallicity compared to previous measurements same authors but significantly lower (∼25%) than recommended value from decade ago Grevesse & Sauval. compare results our structure inferred through helioseismology measurements. model that uses abundance base convective envelope be located at RCZ = 0.724 R☉ and surface helium...
We use asteroseismic data from the Kepler satellite to determine fundamental stellar properties of 66 main-sequence targets observed for at least one full year by mission. distributed tens individual oscillation frequencies extracted time series each star among seven modelling teams who applied different methods radii, masses, and ages all stars in sample. Comparisons results reveal a good level agreement properties, which is remarkable considering variety codes, input physics analysis...
A search of the time-series photometry from NASA's Kepler spacecraft reveals a transiting planet candidate orbiting 11th magnitude G5 dwarf KIC 10593626 with period 290 days. The characteristics host star are well constrained by high-resolution spectroscopy combined an asteroseismic analysis photometry, leading to estimated mass and radius 0.970 ± 0.060 M☉ 0.979 0.020 R☉. depth 492 10 ppm for three observed transits yields 2.38 0.13 Re planet. system passes battery tests false positives,...