A5044836182- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- History and Developments in Astronomy
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astronomical and nuclear sciences
- Calibration and Measurement Techniques
- Atmospheric Ozone and Climate
- Historical Astronomy and Related Studies
- Historical Geography and Cartography
- Advanced Measurement and Metrology Techniques
- Particle Accelerators and Free-Electron Lasers
- Molecular Spectroscopy and Structure
- GNSS positioning and interference
- Space Exploration and Technology
- Offshore Engineering and Technologies
- Optical Polarization and Ellipsometry
- Geophysics and Sensor Technology
- Technology Use by Older Adults
Johns Hopkins University
2015-2024
Johns Hopkins University School of Advanced International Studies
2014
Vanderbilt University
2009
SUNY Geneseo
2009
École Polytechnique Fédérale de Lausanne
2009
University of Hawaii at Hilo
2009
Indiana University Bloomington
2009
University of Baltimore
2009
Osservatorio Astronomico di Padova
2008
University of Padua
2008
We report the discovery of five T Tauri star systems, two which are resolved binaries, in vicinity nearest known region recent formation, TW Hydrae Association. The newly discovered systems display same signatures youth (namely high X-ray flux, large Li abundance and strong chromospheric activity) proper motion as original members. These similarities firmly establish group a bona fide association, unique its proximity to Earth complete isolation from any molecular clouds. At an age ~10 Myr...
In this paper we present the astro-photometric catalogues of 56 globular clusters and one open cluster. Astrometry photometry are mainly based on images collected within "HST Legacy Survey Galactic Globular Clusters: Shedding UV Light Their Populations Formation" (GO-13297, PI:~Piotto), "ACS Clusters" (GO-10775, PI:~Sarajedini). For each source in for which have reliable proper motion also publish a membership probability separation field cluster stars. These new catalogues, make public...
We present color-magnitude diagram analysis of deep Hubble Space Telescope imaging a mass-limited sample 18 intermediate-age (1 - 2 Gyr old) star clusters in the Magellanic Clouds, including 8 for which new data was obtained. find that ${\it all}$ our feature extended main sequence turnoff (eMSTO) regions are wider than can be accounted by simple stellar population (including unresolved binary stars). FWHM widths MSTOs indicate age spreads 200-550 Myr. evaluate dynamical evolution with and...
We report rotation periods for 20 cool (FGK) main sequence member stars of the 4 Gyr-old open cluster M 67 (= NGC 2682), obtained by analysing data from Campaign 5 K2 mission with Kepler Space Telescope. The delineate a in color-period diagram (CPD) increasing period redder color. This represents cross-section at age surface P = (t, M), suggested prior work to extend least solar age. current Sun is located marginally (approx. one sigma) above CPD, as its relative leads us expect, and lies on...
It is now well established that globular clusters (GCs) exhibit star-to-star light-element abundance variations (known as multiple stellar populations, MPs). Such chemical anomalies have been found in (nearly) all the ancient GCs (more than 10 Gyr old) of our Galaxy and its close companions, but so far no model for origin MPs able to reproduce relevant observations. To gain new insights into this phenomenon, we undertaken a photometric Hubble Space Telescope survey study with masses...
We present a revised catalog of 2106 Galactic stars, selected without kinematic bias and with available radial velocities, distance estimates, metal abundances in the range -4.0 ≤ [Fe/H] 0.0. This update 1995 Beers & Sommer-Larsen includes newly derived homogeneous photometric velocities for number stars recently obtained high-resolution spectra, refined metallicities originally identified HK objective-prism survey (which account nearly half catalog) based on recent recalibration. A subset...
Context. The solar-age open cluster M 67 (C0847+120, NGC 2682) is a touchstone in studies of the old Galactic disk. Despite its outstanding role, census membership for at fainter magnitudes and their properties are not well-established.
Omega Centauri is the most well studied Globular Cluster because of its numerous puzzling features. Intensive spectroscopic follow-up observing campaigns targeting stars at different positions on color-magnitude diagram promises to clarify some these peculiarities. To able target cluster members reliably during surveys and both spatial radial distributions in outskirts without including field stars, a high quality proper-motion catalog omega Cen membership probability determination are...
This is the second paper in our series about search for multiple populations Magellanic Cloud star clusters using Hubble Space Telescope. Here we report detection of stellar colour-magnitude diagrams intermediate-age Lindsay 1, NGC 416 and 339. With ages between 6.0 7.5 Gyr, these are youngest ones which chemical abundance spreads have been detected so far. confirms that appearance not restricted to only ancient globular clusters, but may also be a common feature as young 6 Gyr. Our results...
We present the current state of WOCS radial-velocity (RV) survey for rich open cluster NGC 6819 (2.5 Gyr) including 93 spectroscopic binary orbits with periods ranging from 1.5 to 8,000 days. These results are product our ongoing RV using Hydra Multi-Object Spectrograph on WIYN 3.5 m telescope. also include a detailed analysis multiple prior sets optical photometry 6819. Within 1-degree field view, stellar sample includes giant branch, red clump, and blue straggler candidates, extends almost...
We present the third paper about our ongoing HST survey for search multiple stellar populations (MPs) within Magellanic Cloud clusters. report here analysis of NGC 419, a $\sim 1.5$ Gyr old, massive ($\gtrsim 2 \times 10^5 \, {\rm M_{\odot}}$) star cluster in Small (SMC). By comparing photometric data with isochrones, we set limit on [N/Fe] enhancement $\lesssim$+0.5 dex and hence find that no MPs are detected this cluster. This is surprising because, first two papers series, found evidence...
We have recently shown that the $\sim2$ Gyr old Large Magellanic Cloud star cluster NGC 1978 hosts multiple populations in terms of star-to-star abundance variations [N/Fe]. These can be seen as a splitting or spread sub-giant and red giant branches (SGB RGB) when certain photometric filter combinations are used. Due to its relative youth, used place stringent limits on whether bursts star-formation taken within cluster, predicted by some models for origin populations. carry out two distinct...
We analyze the K band luminosities of a sample galactic long-period variables using parallaxes measured by Hipparcos mission. The are in most cases re-computed from Intermediate Astrometric Data improved astrometric fits and chromaticity corrections. magnitudes taken literature measurements COBE, corrected for interstellar circumstellar extinction. contains stars several spectral types: M, S C, variability classes: Mira, semiregular SRa, SRb. find that distribution period-luminosity plane is...
We present the current results from our ongoing radial-velocity (RV) survey of intermediate-age (2.4 Gyr) open cluster NGC 6819. Using both newly observed and other available photometry astrometry, we define a primary target sample 1454 stars that includes main-sequence, subgiant, giant, blue straggler stars, spanning magnitude range 11 ⩽V⩽ 16.5 an approximate mass 1.1–1.6 M☉. Our covers 23 arcminute (13 pc) square field view centered on cluster. have measured 6571 radial velocities for...
In the context of ESA M5 (medium mission) call we proposed a new satellite mission, Theia, based on relative astrometry and extreme precision to study motion very faint objects in Universe. Theia is primarily designed local dark matter properties, existence Earth-like exoplanets our nearest star systems physics compact objects. Furthermore, about 15 $\%$ mission time was dedicated an open observatory for wider community propose complementary science cases. With its unique metrology system...
We started a photometric survey using the WFC3/UVIS instrument onboard Hubble Space Telescope to search for multiple populations within Magellanic Cloud star clusters at various ages. In this paper, we introduce survey. As first results of programme, also present multi-band observations NGC 121 in different filters taken with and ACS/WFC instruments. analyze colour-magnitude diagram (CMD) 121, which is only "classical" globular cluster Small Cloud. Thereby, use pseudo-colour...
In our HST photometric survey, we have been searching for multiple stellar populations (MPs) in Magellanic Clouds (MCs) massive star clusters which span a significant range of ages ($\sim 1.5-11$ Gyr). the previous papers series, shown that age cluster represents one key factors shaping origin chemical anomalies. Here present analysis four additional MCs, namely Lindsay 38, 113, NGC 2121 and 2155, recently obtained new UV observations. These are more than $\sim 10^4M_{\odot}$ between 2.5-6$...