A5038786966- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Scientific Computing and Data Management
- Stellar, planetary, and galactic studies
- Research Data Management Practices
- Distributed and Parallel Computing Systems
- History and Developments in Astronomy
- Gamma-ray bursts and supernovae
- Advanced Control Systems Optimization
- Advanced Data Storage Technologies
- scientometrics and bibliometrics research
- Mathematics, Computing, and Information Processing
- Adaptive optics and wavefront sensing
- Advanced Database Systems and Queries
- Historical Astronomy and Related Studies
- Data Quality and Management
- Semantic Web and Ontologies
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- SAS software applications and methods
- Fault Detection and Control Systems
- Scientific Research and Discoveries
- Advanced Text Analysis Techniques
- Topic Modeling
Center for Astrophysics Harvard & Smithsonian
2011-2022
Smithsonian Astrophysical Observatory
2008-2020
Harvard University Press
1993-2019
University of Maryland, College Park
2013-2019
University of Münster
2019
Cleveland State University
2012
University of Michigan–Ann Arbor
1987-2011
National Archives and Records Administration
2010
Harvard University
1988-2008
Hartford Financial Services (United States)
2003-2008
The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in spring of 2004. In configuration pioneered by Autofib instrument Anglo‐Australian Telescope, Hectospec's probes are arranged radial "fisherman on pond" geometry and held position with small magnets. A pair high‐speed, six‐axis robots move buttons between observing configurations within ∼300 s, to an accuracy ∼25 μm. fibers run for 26 m MMT's focal surface bench spectrograph, operating R∼1000–2000. Hectochelle,...
RVSAO is a set of programs to obtain redshifts and radial velocities from digital spectra. operates in the IRAF environment. The heart system xcsao, which implements cross‐correlation method direct descendant built by Tonry & Davis. emsao uses intelligent heuristics search for emission lines spectra, then fits them redshift. sumspec shifts sums spectra build templates cross‐correlation. linespec builds synthetic given list spectral lines. bcvcorr corrects motion Earth. We discuss detail...
The Zwicky Catalog of galaxies (ZC), with mZw≤15.5, has been the basis for Center Astrophysics (CfA) redshift surveys. To date, analyses ZC and surveys based on it have relied heterogeneous sets galaxy coordinates redshifts. Here we correct some inadequacies previous catalogs by providing (1) ≲2 '' errors all 19,369 catalog galaxies, (2) homogeneously estimated redshifts majority (98%) data taken at CfA (14,632 spectra), (3) an estimate remaining "blunder" rate both those compiled from...
We have discovered a star, SDSS J090745.0+024507, leaving the Galaxy with heliocentric radial velocity of 853 ± 12 km s-1, largest ever observed in Milky Way halo. The star is either hot blue horizontal-branch or B9 main-sequence distance 39 71 kpc, respectively. Corrected for solar reflex motion and to local standard rest, Galactic rest-frame 709 s-1. suggest that this first example hypervelocity ejected from center, as predicted by Hills later discussed Yu & Tremaine. star's vector points...
The CAIRNS (Cluster and Infall Region Nearby Survey) project is a spectroscopic survey of the infall regions surrounding eight nearby, rich, X-ray–luminous clusters galaxies. We have collected 15,654 redshifts (3471 new or remeasured) within ∼5–10 h-1 Mpc centers clusters, making it largest study clusters. determine cluster membership mass profiles based on phase-space distribution All display decreasing velocity dispersion profiles. are fitted well by functional forms numerical simulations...
The infall regions of galaxy clusters represent the largest gravitationally bound structures in a ΛCDM universe. Measuring cluster mass profiles into provides an estimate ultimate these halos. We use caustic technique to measure from redshifts obtained with Hectospec Cluster Survey (HeCS), extensive spectroscopic survey MMT/Hectospec. 58 selected by X-ray flux at 0.1 < z 0.3. includes 22,680 unique MMT/Hectospec for individual galaxies; 10,145 galaxies are members. For each cluster, we...
The solar wind interacts very strongly with the extensive cometary coma, and various interaction processes are initiated by ionization of neutrals. main mechanism far outside bow shock is photoionization extreme ultraviolet radiation. Electron distributions measured in vicinity comets Halley Giacobini‐Zinner instruments on VEGA ICE spacecraft, respectively, used to calculate electron impact frequencies. Ionization electrons comparable importance magnetosheaths Comets Giacobini‐Zinner....
We calculate the stellar mass-metallicity relation at five epochs ranging to z~2.3. quantify evolution in shape of as a function redshift; flattens late times. There is an empirical upper limit gas-phase oxygen abundance star-forming galaxies that independent redshift. From examination and its observed scatter we show flattening times consequence mass where enrich this metallicity limit; there also fraction fixed limit. The metallicities begin saturate ~0.7 dex smaller local universe than it z~0.8.
Scholarly usage data provides unique opportunities to address the known shortcomings of citation analysis. However, collection, processing and analysis remains an area active research. This article a review state-of-the-art in usage-based informetric, i.e. use study scholarly process.
We precisely constrain the inner mass profile of Abell 2261 (z=0.225) for first time and determine this cluster is not "over-concentrated" as found previously, implying a formation in agreement with ΛCDM expectations. These results are based on strong lensing analyses new 16-band HST imaging obtained part Cluster Lensing Supernova survey Hubble (CLASH). Combining revised weak Subaru wide field 5-band + KPNO photometry, we place tight constraints halo virial M_vir = 2.2\pm0.2\times10^15...
We report redshifts, magnitudes, and morphological classifications for 5369 galaxies with mB ≤ 15.5 57 fainter than this limit, in two regions covering a total of 1.70 sr the southern celestial hemisphere. The galaxy catalog is drawn primarily from list nonstellar objects identified Hubble Space Telescope Guide Star Catalog (GSC). have positions accurate to ∼1'' magnitudes an rms scatter ∼0.3 mag. compute (mSSRS2) relation between instrumental GSC photometry by Lauberts & Valentijn. From...
view Abstract Citations (185) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Complete Southern Sky Redshift Survey da Costa, L. Nicolaci ; Geller, M. J. Pellegrini, P. S. Latham, D. W. Fairall, A. Marzke, R. O. Willmer, C. N. Huchra, Calderon, H. Ramella, Kurtz, We discuss a magnitude-limited redshift survey covering region around the south Galactic pole (SSRS2). The includes 3592 galaxies and covers of 1.13 sr to limiting m_B(0)_ = 15.5,...
The disruption of binary stars by the tidal field black hole in Galactic Center can produce hypervelocity observed halo. We use numerical models to simulate full spectrum observable velocities ejected into halo this process. Our model includes a range parameters for binaries with 3-4 M_Solar primaries, consideration radial orbits through an approximate mass distribution Galaxy, and impact stellar lifetimes. calculate ejection reproduce previous results mean velocity at center. predicts that...
Abstract Digital libraries such as the NASA Astrophysics Data System (Kurtz et al., 2005) permit easy accumulation of a new type bibliometric measure, number electronic accesses (“reads”) individual articles. We explore various aspects this measure. examine obsolescence function measured by actual reads and show that it can be well fit sum four exponentials with very different time constants. compare readership citations. find citation is proportional to two components function. This proves...
We use a new redshift survey complete to m_R=15.4 within 4.25 deg from the center of Coma cluster measure mass profile r=5.5 Mpc/h. extend r=10 Mpc/h with further sample in 42% area 10 radius and m_{Zw}=15.5 remaining area. Galaxies this region are falling onto on moderately radial orbits thus do not satisfy virial equilibrium. Nonetheless, identification caustics space provides an estimate gravitational potential at r hence system mass, M(<10 Mpc/h)=(1.65+-0.41)10^{15} M_\odot/h (1-sigma...
Mechanistic dynamic models often contain unknown parameters whose values are difficult to determine even with highly specialized laboratory experiments. A practical approach is estimate such from available process data. Typically only a subset of the can be estimated due restrictions imposed by model structure, lack measurements, and limited We present simple parameter selection method which accounts for first two factors independent data estimation. The magnitude each effect on measured...
We investigate the environmental dependence of star formation in cluster virial regions and infall as part CAIRNS (Cluster And Infall Region Nearby Survey), a large spectroscopic survey surrounding nine nearby rich clusters galaxies. Our long-slit spectroscopy yields estimates rates environments from cores to general large-scale structure. The fraction galaxies with current their inner disks traced by H-alpha emission increases distance converges ``field'' value only at 2-3 radii, agreement...
We discuss our targeted search for hypervelocity stars (HVSs), traveling with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Our survey, now half-complete, has successfully identified total of four probable HVSs plus number other unusual objects. Here we report the two most recently discovered HVSs: SDSS J110557.45+093439.5 and possibly J113312.12+010824, Galactic rest-frame at least +508 ± 12 +418 10 km s-1, respectively. The late...
We report the discovery of three new unbound hypervelocity stars (HVSs), traveling with such extreme velocities that dynamical ejection from a massive black hole (MBH) is their only suggested origin. also detect population possibly bound HVSs. The significant asymmetry we observe in velocity distribution—we find 26 vrf > 275 km s−1 and one star < − s−1—shows HVSs must be short-lived, probably 3-4 M☉ main-sequence stars. Any post-main-sequence should contain falling back onto Galaxy, contrary...
Authorship and citation practices evolve with time differ by academic discipline. As such, indicators of research productivity based on records are naturally subject to historical disciplinary effects. We observe these effects a corpus astronomer career data constructed from database refereed publications. employ simple mechanism measure output using author reference counts available in bibliographic databases develop citation-based indicator productivity. The total impact (tori) quantifies,...