A5006115143- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Radio Astronomy Observations and Technology
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- GNSS positioning and interference
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Magnetic confinement fusion research
- Galaxies: Formation, Evolution, Phenomena
- Ionosphere and magnetosphere dynamics
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Earthquake Detection and Analysis
National Radio Astronomy Observatory
2015-2024
Max Planck Society
2015-2016
Max Planck Institute for Radio Astronomy
2015-2016
Universidad de Guadalajara
2014
Universidad Nacional Autónoma de México
2007
Valparaiso University
2007
Georgia State University
2007
New Mexico Institute of Mining and Technology
2007
Joint Institute for VLBI ERIC
1999-2004
The University of Sydney
2000-2001
We present the results of Gould's Belt Distances Survey young star-forming regions toward Orion Molecular Cloud Complex. detected 36 stellar objects (YSOs) with Very Large Baseline Array, 27 which have been observed in at least three epochs over course two years. At half these YSOs belong to multiple systems. obtained parallax and proper motions stars study structure kinematics measured a distance 388 ± 5 pc Nebula Cluster, 428 10 southern portion L1641, NGC 2068, roughly ∼420 2024. Finally,...
The nonthermal 3.6 cm radio continuum emission from the young stars S1 and DoAr 21 in core of Ophiuchus has been observed with Very Long Baseline Array (VLBA) at 6 7 epochs, respectively, between June 2005 August 2006. typical separation successive observations was 2-3 months. Thanks to remarkably accurate astrometry delivered by VLBA, trajectory described both on plane sky could be traced very precisely, modeled as superposition their trigonometric parallax a uniform proper motion. best...
Using multiepoch Very Long Baseline Array (VLBA) observations, we have measured the trigonometric parallax of weak-line T Tauri star HP Tau/G2 in Taurus. The best fit yields a distance 161.2 ± 0.9 pc, suggesting that eastern portion Taurus (where is located) corresponds to far side complex. Previous VLBA observations shown Tau, south complex, at an intermediate about 147 whereas region around L1495 near roughly 130 pc. Our only four sources are still too coarse enable reliable determination...
Using the Very Long Base Array, we observed young stellar object EC 95 in Serpens cloud core at eight epochs from December 2007 to 2009. Two sources are detected our field, and shown form a tight binary system. The primary (EC 95a) is 4--5 $M_\odot$ proto-Herbig AeBe (arguably youngest such known), whereas secondary 95b) most likely low-mass T Tauri star. Interestingly, both non-thermal emitters. While stars expected power corona because they convective while go down Hayashi track,...
The non-thermal 3.6 cm radio continuum emission from the naked T Tauri stars Hubble 4 and HDE 283572 in Taurus has been observed with Very Long Baseline Array (VLBA) at 6 epochs between September 2004 December 2005 a typical separation successive observations of 3 months. Thanks to remarkably accurate astrometry delivered by VLBA, trajectory described both on plane sky could be traced very precisely, modeled as superposition their trigonometric parallax uniform proper motion. best fits yield...
We present the first results of Gould's Belt Distances Survey (GOBELINS), a project aimed at measuring proper motion and trigonometric parallax large sample young stars in nearby regions using multi-epoch Very Long Baseline Array (VLBA) radio observations. Enough VLBA detections have now been obtained for 16 stellar systems Ophiuchus to derive their motion. This leads distance determinations individual with an accuracy 0.3 few percent. In addition, orbits 6 multiple were modelled by...
Because of its proximity and youth, the Pleiades open cluster stars has been extensively studied serves as a cornerstone for our understanding physical properties young stars. This role is called into question by "Pleiades distance controversy" wherein 120.2+/-1.5 pc measured optical space astrometry mission Hipparcos significantly different from 133.5+/-1.2 derived with other techniques. We present an absolute trigonometric parallax measurement to that uses very long baseline radio...
Abstract We present Gaia -DR2 astrometry of a sample YSO candidates in Ophiuchus, Serpens Main, and South/W40 the Aquila Rift, which had been mainly identified by their infrared excess with Spitzer . compare parallaxes against published new obtained from our Very Long Baseline Array (VLBA) program Gould’s Belt Distances Survey. obtain consistent results between VLBA for mean each regions analyzed here. see small offsets, when comparing values, few tens microarcseconds parallaxes, are either...
High angular resolution images of extragalactic radio sources are being made with the Highly Advanced Laboratory for Communications and Astronomy (HALCA) satellite ground-based telescopes as part Very Long Baseline Interferometry (VLBI) Space Observatory Programme (VSOP). VSOP observations at 1.6 5 gigahertz milli–arc-second–scale structure quasars enable quasar core size corresponding brightness temperature to be determined, they motions jet components that close studied. Here, gamma-ray...
In this article, we present the results of a series 12 3.6 cm radio continuum observations T Tau Sb, one companions famous young stellar object Tauri. The data were collected roughly every 2 months between 2003 September and 2005 July with Very Long Baseline Array (VLBA). Thanks to remarkably accurate astrometry delivered by VLBA, absolute position Sb could be measured precision typically better than about 100 μas at each observed epochs. trajectory on plane sky therefore traced very...
(ABRIDGED) We present multi-epoch Very Long Baseline Array (VLBA) observations of V773 Tau A, the 51-day binary subsystem in multiple young stellar system Tau. Combined with previous interferometric and radial velocity measurements, these new data enable us to improve characterization physical orbit A subsystem. In particular, we infer updated dynamical masses for primary secondary components 1.55 pm 0.11 Msun, 1.293 0.068 respectively, an orbital parallax distance 135.7 3.2 pc, all...
We report on new distances and proper motions to seven stars across the Serpens/Aquila complex. The observations were obtained as part of Gould's Belt Distances Survey (GOBELINS) project between September 2013 April 2016 with Very Long Baseline Array (VLBA). One our targets is proto-Herbig AeBe object EC 95, which a binary system embedded in Serpens Core. For this system, we combined GOBELINS previous VLBA data cover total period ~8 years, derive orbital elements an updated source distance....
Abstract We derive the distance and structure of Perseus molecular cloud by combining trigonometric parallaxes from Very Long Baseline Array (VLBA) observations, taken as part GOBELINS survey Gaia Data Release 2. Based on our VLBA astrometry, we obtain a 321 ± 10 pc for IC 348. This is fully consistent with mean 320 26 measured . The observations toward NGC 1333 are insufficient to claim successful measurement this cluster. parallaxes, other hand, yield 293 22 pc. Hence, along line sight...
Radiation belts are present in all large-scale Solar System planetary magnetospheres: Earth, Jupiter, Saturn, Uranus and Neptune
Abstract We report on the X-ray spectral and spatial evolution of symbiotic star R Aqr. Through a multiepoch observational campaign performed with Chandra between 2017 2022, we study emission this binary system, composed an evolved red giant white dwarf (WD). This analysis is particularly timely as WD approached periastron in late 2018/early 2019; thus, mass transfer, jet emission, outburst phenomena are to be expected. detailed analysis, detect significant rise soft (0.5–2 keV) Aqr, likely...
Very Long Baseline Array images of the X-ray binary Cygnus X-3 were obtained 2, 4, and 7 days after peak a 10 Jy flare on 1997 February 4. The first two show curved one-sided jet, third shows scatter-broadened disk, presumably at position core. jet curvature changes from to second epoch, which strongly suggests precessing jet. ratio flux density in approaching that (undetected) receding is ≳330; if this asymmetry due Doppler boosting, implied speed ≳0.81c. Precessing-jet model fits, together...
We report high-resolution radio imaging of the recurrent nova RS Ophiuchi (RS Oph) during first month 2006 outburst, using Very Long Baseline Array (VLBA). Observations made on days 20.8 and 26.8 outburst show a synchrotron-emitting partial shell that is much brighter to east than west. Assuming broad component infrared lines corresponds outermost part seen by VLBA, distance source 2.45 ± 0.4 kpc. The circular shape spectral indices emission challenge simple models for structure immediately...
Novae occur when hydrogen-rich fuel provided by a companion star ignites on the surface of white dwarf (WD). Although WD is nearly spherical, observations indicate that at least some nova explosions can produce bipolar outflows, or jets. The origin and nature these jets are controversial. Proposed mechanisms for generating include (1) intrinsically asymmetric explosions, (2) ejecta move into an inhomogeneous environment, (3) driving highly collimated outflows such as those from black holes...
We present large-scale ($\sim$ 2000 square arcminutes), deep 20 $\mu$Jy), high-resolution 1$''$) radio observations of the Ophiuchus star-forming complex obtained with Karl G.\ Jansky Very Large Array at $\lambda$ = 4 and 6 cm. In total, 189 sources were detected, 56 them associated known young stellar sources, extragalactic objects; other 129 remain unclassified, but most are probably background quasars. The vast majority stars detected wavelengths have spectral types K or M, although we...
Abstract We present new trigonometric parallaxes and proper motions of young stellar objects in the Taurus molecular cloud complex from observations collected with Very Long Baseline Array as part Gould’s Belt Distances Survey. detected 26 derived for 18 stars an accuracy 0.3% to a few percent. modeled orbits six binaries determined dynamical masses individual components four these systems (V1023 Tau, T Tau S, V807 V1000 Tau). Our results are consistent first delivered by Gaia satellite...
We have imaged the X-ray binary SS 433 with unprecedented Fourier plane coverage at 6 cm using simultaneously Very Long Baseline Array (VLBA), MERLIN, and Large also 20 VLBA. At both wavelengths we securely detected smooth, low surface brightness emission having appearance of a "ruff" or collar attached perpendicularly to well-studied knotty jets in this system extending over least few hundred AU. interpret smooth as windlike outflow from discuss its implications for present evolutionary...
We report on radio observations of the 1999 September event X-ray transient V4641 Sgr (=XTE J1819-254=SAX J1819.3-2525). This was extremely rapid in its rise and decay across radio, optical, wavelengths; X-rays rose to 12 crab within 8 hr faded below 0.1 less than 2 hr. Radio were made with seven telescopes during first day following onset strong event, revealing a source that detected for 3 further weeks by more sensitive telescopes. The resolved even Very Large Array (VLA) images...
Multifrequency observations from the Very Large Array, Long Baseline Array (VLBA), and Owens Valley Radio Observatory Millimeter of a major radio outburst Cygnus X-3 in 2001 September are presented, measuring evolution spectrum source over 3 decades frequency, period 6 days. Following peak flare, as intensity declines high-frequency at frequency ν steepens ν-0.4 to ν-0.6, after which spectral index remains this latter terminal value, trend previously observed but hitherto not satisfactorily...
In this Letter, we present a series of seven observations the compact, non-thermal radio source associated with T Tauri South made Very Long Baseline Array over course one year. The emission is found to be composed compact structure most certainly originating from magnetosphere an underlying pre-main sequence star, and low-brightness extension which may result reconnection flares at star-disk interface. accuracy absolute astrometry offered by VLBA allows very precise determinations...