A5088414346- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Energetic Materials and Combustion
- High-pressure geophysics and materials
- Crystallography and molecular interactions
- Pulsars and Gravitational Waves Research
- Geochemistry and Geologic Mapping
- Laser-induced spectroscopy and plasma
- Solid State Laser Technologies
- Scientific Research and Discoveries
- Inertial Sensor and Navigation
- Solar and Space Plasma Dynamics
- History and Developments in Astronomy
- Chemical Thermodynamics and Molecular Structure
- Atomic and Molecular Physics
- Geological and Geochemical Analysis
- Laser-Matter Interactions and Applications
- Nuclear Physics and Applications
- Nonlinear Optical Materials Research
Max Planck Institute for Astronomy
2019-2024
Bloomberg (United States)
2019-2023
Johns Hopkins University
2018-2023
Max Planck Society
2019
Leibniz Institute for Astrophysics Potsdam
2015-2018
University of Nevada, Las Vegas
2010-2011
Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is fifth data release from a magnitude-limited (9< I < 12) survey stars randomly selected in southern hemisphere. The RAVE medium-resolution spectra ($R\sim7500$) covering Ca-triplet region (8410-8795\AA) span complete time frame start observations 2003 to their completion 2013. velocities 520,781 457,588 unique are presented, which 255,922 stellar have parallaxes and proper motions Tycho-Gaia astrometric solution (TGAS) Gaia DR1....
ABSTRACT We report discovery of a bright, nearby ($G = 13.8;\, \, d 480\, \rm pc$) Sun-like star orbiting dark object. identified the system as black hole candidate via its astrometric orbital solution from Gaia mission. Radial velocities validated and refined solution, spectroscopy ruled out significant light contributions another star. Joint modelling radial astrometry constrains companion mass $M_2 9.62\pm 0.18\, \mathrm{M}_{\odot }$. The spectroscopic orbit alone sets minimum $M_2\gt 5\,...
We use data from the Radial Velocity Experiment (RAVE) and Tycho-Gaia astrometric solution (TGAS) catalogue to compute velocity fields yielded by radial (VR), azimuthal (Vϕ),and vertical (Vz) components of associated Galactocentric velocity. search in particular for variation all three with distance above below disc mid-plane, as well how each component Vz (line-of-sight tangential projections) modifies obtained structure. To study dependence on proper motion distance, we two main samples: a...
Radial velocities of 2768 fundamental mode RR Lyrae stars (RRLs) toward the Southern Galactic bulge are presented, spanning southern from -8 < l +8 and -3 b <-6. Distances derived pulsation properties RRLs combined with Gaia proper motions to give constraints on orbital 1389 RRLs. The majority (~75%) have orbits consistent these being permanently bound <3.5 kpc Center, similar bar. However, unlike giants, exhibit slower rotation a higher velocity dispersion. dispersion arises almost...
We combine parallaxes from the first Gaia data release with spectrophotometric distance estimation framework for stars in fifth RAVE survey release. The combined estimates are more accurate than either determination isolation - uncertainties on average two times smaller RAVE-only distances (three dwarfs), and 1.4 TGAS parallax (two giants). also able to compare spectrophotometry those Gaia, use this assess reliability of both catalogues improve our estimates. find that lowest log g are,...
We present evidence from the RAdial Velocity Experiment (RAVE) survey of chemically separated, kinematically distinct disc components in solar neighbourhood. apply probabilistic chemical selection criteria to separate our sample into α-low ('thin disc') and α-high ('thick sequences. Using newly derived distances, which will be utilized upcoming RAVE DR5, we explore kinematic trends as a function metallicity for each components. For disc, find negative trend mean rotational velocity (Vϕ) iron...
We measured [Fe/H] and [$\alpha$/Fe] using spectral synthesis of low-resolution stellar spectroscopy for 70 individual red giant branch stars across four fields spanning the outer disk, Giant Stellar Stream (GSS), inner halo M31. Fields at M31-centric projected distances 23 kpc in halo, 12 22 GSS, 26 disk are $\alpha$-enhanced, with $\langle$[$\alpha$/Fe]$\rangle$ = 0.43, 0.50, 0.41, 0.58, respectively. The relatively metal-poor, $\langle$[Fe/H]$\rangle$ $-$1.54 $-$1.30, whereas GSS...
We characterize the selection function of RAVE using 2MASS as our underlying population, which we assume represents all stars could have potentially been observed. evaluate completeness fraction a position, magnitude, and color in two ways: first, on field-by-field basis, second, equal-size areas sky. Then, consider effect stellar parameter pipeline final resulting catalogue, principle limits space over is valid. Our product pipeline. then test if application introduces biases derived...
Measurements of [Fe/H] and [$\alpha$/Fe] can probe the minor merging history a galaxy, providing direct way to test hierarchical assembly paradigm. While measurements have been made in stellar halo Milky Way, little is known about detailed chemical abundances M31. To make progress with existing telescopes, we apply spectral synthesis low-resolution DEIMOS spectroscopy (R $\sim$ 2500 at 7000 Angstroms) across wide range (4500 Angstroms $<$ $\lambda$ 9100 Angstroms). By applying our technique...
We analyze existing measurements of [Fe/H] and [$\alpha$/Fe] for individual red giant branch (RGB) stars in the Giant Stellar Stream (GSS) M31 to determine whether spatial abundance gradients are present. These were obtained from low- ($R \sim 3000$) moderate- 6000$) resolution Keck/DEIMOS spectroscopy using spectral synthesis techniques as part Elemental Abundances survey. From a sample 62 RGB spanning GSS at 17, 22, 33 projected kpc, we measure gradient $-$0.018 $\pm$ 0.003 dex kpc$^{-1}$...
We present initial results from a large spectroscopic survey of stars throughout M33's stellar disk. analyze sample 1667 red giant branch (RGB) extending to projected distances $\sim 11$ kpc center ($\sim 18$ kpc, or 10$ scale lengths, in the plane disk). The line-of-sight velocities RGB show presence two kinematical components. One component is consistent with rotation HI disk and has velocity dispersion 19$ km s$^{-1}$) that observed comparison younger stars, while second significantly...
We present part 2 of the 6th and final Data Release (DR6 or FDR) Radial Velocity Experiment (RAVE), a magnitude-limited (9<I<12) spectroscopic survey Galactic stars randomly selected in southern hemisphere. The RAVE medium-resolution spectra (R~7500) cover Ca-triplet region (8410-8795A) span complete time frame from start observations on 12 April 2003 to their completion 4 2013. In second two publications, we data products derived 518387 451783 unique using suite advanced reduction pipelines...
We present chemical abundances of red giant branch (RGB) stars in the dwarf spheroidal (dSph) satellite system Andromeda (M31), using spectral synthesis medium resolution (R $\sim 6000$) spectra obtained with Keck II telescope and DEIMOS spectrograph via Spectroscopic Photometric Landscape Andromeda's Stellar Halo (SPLASH) survey. coadd according to their similarity photometric metallicity or effective temperature obtain a signal-to-noise ratio (S/N) high enough measure average [Fe/H]...
Abstract We present deep spectroscopy from Keck/DEIMOS of Andromeda I, III, V, VII, and X, all which are dwarf spheroidal satellites M31. The sample includes 256 spectroscopic members across five dSphs. confirm previous measurements the velocity dispersions dynamical masses, we provide upper limits on bulk rotation. Our that M31 obey same relation between stellar mass metallicity as Milky Way (MW) other galaxies in Local Group. distributions show trends with similar to those MW satellites,...
Abstract The Radial Velocity Experiment (R ave ) is a magnitude-limited (9 < I 12) spectroscopic survey of Galactic stars randomly selected in Earth’s southern hemisphere. R medium-resolution spectra ( ∼ 7500) cover the Ca-triplet region (8410–8795 Å). sixth and final data release (DR6) based on 518,387 observations 451,783 unique stars. were taken between 2003 April 12 2013 4. Here we present genesis, setup, reduction as well wavelength-calibrated flux-normalized error for all DR6....
Stellar kinematics and metallicity are key to exploring formation scenarios for galactic disks halos. In this work, we characterized the relationship between photometric along line-of-sight M31's disk. We combined optical HST/ACS photometry from Panchromatic Hubble Andromeda Treasury (PHAT) survey with Keck/DEIMOS spectra Spectroscopic Photometric Landscape of Andromeda's Halo (SPLASH) survey. The resulting sample 3512 individual red giant branch stars spans 4-19 projected kpc, making it a...
Abstract We present spectroscopic chemical abundances of red giant branch stars in Andromeda (M31), using medium-resolution ( R ∼ 6000) spectra obtained via the Spectroscopic and Photometric Landscape Andromeda’s Stellar Halo survey. In addition to individual abundances, we coadd low signal-to-noise ratio obtain a high enough signal measure average [Fe/H] [ α /Fe] abundances. coadded measurements for M31 halo stars, covering range 9–180 kpc projected radius from center M31. With these...
We report the identification of extended tidal debris potentially associated with globular cluster NGC 3201, using RAVE catalogue. find stars are located at a distance range 1-7 kpc based on forthcoming estimates. The derived space velocities and integrals motion show interesting connections to modulo uncertainties in proper motions. Three stars, which among 4 most likely candidates for 3201 debris, separated by 80 degrees sky yet well matched 12 Gyr, [Fe/H] = -1.5 isochrone appropriate...
ABSTRACT A large sample of over 38,000 chromospherically active candidate solar-like stars and cooler dwarfs from the RAVE survey is addressed in this paper. An improved activity identification with respect to previous study was introduced build a catalog field solar neighborhood an excess emission flux calcium infrared triplet wavelength region. The central result work calibration age–activity relation for main-sequence range few <?CDATA $10\ \mathrm{Myr}$?> up Gyr. It enabled order...
Abstract We present measurements of [Fe/H] and [ α /Fe] for 128 individual red giant branch stars (RGB) in the stellar halo M31, including its Giant Stellar Stream (GSS), obtained using spectral synthesis low- medium-resolution Keck/DEIMOS spectroscopy ( <?CDATA $R\sim 3000$?> 6000, respectively). observed four fields M31's (at projected radii 9, 18, 23, 31 kpc), as well two GSS 33 kpc). In combination with existing literature measurements, we have increased sample size from 101 to a total...
We explore the connections between stellar age, chemistry, and kinematics across a Galactocentric distance of $7.5 < R\,(\mathrm{kpc}) 9.0$, using sample $\sim 12\,000$ intermediate-mass (FGK) turnoff stars observed with RAdial Velocity Experiment (RAVE) survey. The this are determined radial velocity measurements from RAVE, parallax proper motion Tycho-Gaia Astrometric Solution (TGAS). In addition, ages for RAVE Bayesian method, taking TGAS parallaxes as prior. divide our into young ($0...
We report a synchrotron energy-dispersive X-ray diffraction study of the novel high explosive 1,1-diamino-2,2-dinitroethylene at pressures and temperatures. Pressure was generated using Paris–Edinburgh cell to employ larger sample volumes. High temperatures were created resistive graphite cylinder surrounding sample. The PT phase diagram explored in 3.3 GPa pressure range ∼ 400°C temperature range. believe that commenced α-phase then ended up an amorphous when increased beyond 280°C near 2...
We present the first measurements of [Fe/H] and [$\alpha$/Fe] abundances, obtained using spectral synthesis modeling, for red giant branch stars in M31's stellar stream. The spectroscopic observations, at a projected distance 17 kpc from center, yielded 61 with measurements, including 21 112 targets identified as M31 stars. confirm expectation photometric metallicity estimates that this region halo are relatively metal-rich compared to MW's inner halo: more than half field, those not...
Star clusters are invaluable tracers of the Galactic components and discovery characterization low-mass stellar systems can be used to appraise their prevailing disruption mechanisms time scales. However, owing significant foreground contamination, high extinction, still uncharted interfaces underlying Milky Way components, objects at low latitudes notoriously difficult characterize. Here, we present first spectroscopic campaign identify chemodynamical properties low-latitude star cluster...