Steven Pravdo - JPL

Steven Pravdo
Are you Steven Pravdo?

Claim your profile, edit publications, add additional information:

Contact Details

Name
Steven Pravdo
Affiliation
JPL
Location

Pubs By Year

External Links

Pub Categories

 
Astrophysics (13)
 
Instrumentation and Methods for Astrophysics (2)
 
Solar and Stellar Astrophysics (1)
 
Earth and Planetary Astrophysics (1)
 
High Energy Astrophysical Phenomena (1)

Publications Authored By Steven Pravdo

2015Oct
Affiliations: 1Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 2Jet Propulsion Laboratory, 3California Institute of Technology, Cahill Center for Astronomy and Astrophysics, 4Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 5Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 6Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 7Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 8Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 9Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 10Anton Pannekoek Institute for Astronomy, 11California Institute of Technology, Cahill Center for Astronomy and Astrophysics, 12California Institute of Technology, Cahill Center for Astronomy and Astrophysics, 13Jet Propulsion Laboratory, 14Jet Propulsion Laboratory, 15Rice University, Department of Physics and Astronomy, 16Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 17Georgia College, Department of Chemistry, Physics, and Astronomy, 18Jet Propulsion Laboratory, 19Jet Propulsion Laboratory, 20North-West University, Centre for Space Research, 21Technical University of Denmark, DTU Space, National Space Institute, 22Yale University, Department of Astronomy, 23Washington University in Saint Louis, Physics Department and McDonnell Center for the Space Sciences, 24University of Virginia, Department of Astronomy, 25MPI for Extraterrestrial Physics Garching, 26Durham University, Centre for Extragalactic Astronomy, Department of Physics, 27Jet Propulsion Laboratory, 28North Carolina State University, Department of Physics, 29Jet Propulsion Laboratory, 30Cambridge, Institute of Astronomy, UK, 31Penn State University, Department of Astronomy and Astrophysics, 32Jet Propulsion Laboratory, 33University of California, Berkeley, Department of Physics, 34ASI Science Data Center, Italy, 35California Institute of Technology, Cahill Center for Astronomy and Astrophysics, 36Cambridge, Institute of Astronomy, UK, 37Jet Propulsion Laboratory, 38Purdue University, Department of Physics and Astronomy, 39Texas Tech University, Physics Department, 40Nagoya University, Center for Experimental Studies, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, 41University of Maryland, Physics Department, 42RIKEN, 43Univ. of Michigan in Ann Arbor, Astronomy Dept, 44Harvard-Smithsonian Center for Astrophysics, 45Istituto di Astrofisica e Planetologia Spaziali, INAF, 46Department of Astronomy/Steward Observatory, 47Lawrence Livermore National Laboratory, 48Jet Propulsion Laboratory, 49Department of Astronomy/Steward Observatory, 50NASA Goddard Space Flight Center, 51Tohoku University, Astronomical Institute, 52NASA Goddard Space Flight Center

This paper describes the Polarization Spectroscopic Telescope Array (PolSTAR), a mission proposed to NASA's 2014 Small Explorer (SMEX) announcement of opportunity. PolSTAR measures the linear polarization of 3-50 keV (requirement; goal: 2.5-70 keV) X-rays probing the behavior of matter, radiation and the very fabric of spacetime under the extreme conditions close to the event horizons of black holes, as well as in and around magnetars and neutron stars. Read More

We are undertaking an astrometric search for gas giant planets and brown dwarfs orbiting nearby low mass dwarf stars with the 2.5-m du Pont telescope at the Las Campanas Observatory in Chile. We have built two specialized astrometric cameras, the Carnegie Astrometric Planet Search Cameras (CAPSCam-S and CAPSCam-N), using two Teledyne Hawaii-2RG HyViSI arrays, with the cameras' design having been optimized for high accuracy astrometry of M dwarf stars. Read More

We report here the discovery of the first planet around an ultracool dwarf star. It is also the first extrasolar giant planet (EGP) astrometrically discovered around a main-sequence star. The statistical significance of the detection is shown in two ways. Read More

We have used the Palomar 200" Adaptive Optics (AO) system to directly detect the astrometric brown dwarf GJ 802B reported by Pravdo et al. 2005. This observation is achieved with a novel combination of aperture masking interferometry and AO. Read More

The Stellar Planet Survey (STEPS) is an ongoing astrometric search for giant planets and brown dwarfs around a sample of ~30 M-dwarfs. We have discovered several low-mass companions by measuring the motion of our target stars relative to their reference frames. The highest mass discovery thus far is G 78-28B, a companion to the M-dwarf G 78-28A. Read More

The Stellar Planet Survey is an ongoing astrometric search for giant planets and brown dwarfs around a sample of about 30 M-dwarfs. We have discovered several low-mass companions by measuring the motion of our target stars relative to their reference frames. The lowest mass discovery thus far is GJ 802b, a companion to the M5-dwarf GJ 802A. Read More

We report the discovery of X-rays from both components of Cepheus A, East and West, with the XMM-Newton Observatory. HH 168 joins the ranks of other energetic Herbig Haro objects that are sources of T~10^6 K X-ray emission. The HH 168 effective temperature is T = 5. Read More

We discovered a low-mass companion to the M-dwarf GJ 164 with the CCD-based imaging system of the Stellar Planet Survey (STEPS) astrometric program. The existence of GJ 164B was confirmed with Hubble Space Telescope NICMOS imaging observations. A high-dispersion spectral observation in V sets a lower limit of delta m> 2. Read More

We present results of Chandra observations of two flanking fields (FF) in Orion, outside the Orion Nebula Cluster (ONC). The observations were taken with the ACIS-I camera with an exposure time of about 48 ks each field. We present a catalog of 417 sources, which includes X-ray luminosity, optical and infrared photometry and X-ray variability information. Read More

We report detections of X-rays from HH 80 and HH 81 with the ACIS instrument on the Chandra X-ray Observatory. These are among the most luminous HH sources in the optical and they are now the most luminous known in X-rays. These X-rays arise from the strong shocks that occur when the southern extension of this bipolar outflow slams into the ambient material. Read More

2004Jan
Affiliations: 1SSC, Caltech, 2SSC, Caltech, 3SSC, Caltech, 4JPL, 5Caltech, 6UC Santa Cruz, 7STSI, 8JPL, 9NOAO, 10JPL
Category: Astrophysics

We present results of a Chandra observation of a field in NGC 2264. The observations were taken with the ACIS-I camera with an exposure time of 48.1 ks. Read More

We report the X-ray detection of the brown dwarf (BD) companion TWA 5B in a $\simeq 12$ Myr old pre-main sequence binary system. We clearly resolve the faint companion (35 photons) separated from the X-ray luminous primary by 2 arcsec in a {\it Chandra} ACIS image. TWA 5B shows a soft X-ray spectrum with a low plasma temperature of only 0. Read More

The Orion Nebula Cluster and the molecular cloud in its vicinity have been observed with the ACIS-I detector on board the Chandra X-ray Observatory with 23 hours exposure. We detect 1075 X-ray sources: 91% are spatially associated with known stellar members of the cluster, and 7% are newly identified deeply embedded cloud members. This provides the largest X-ray study of a pre-main sequence stellar population. Read More

To address the role of energetic processes in the solar nebula, we provide a detailed characterization of magnetic flaring in stellar analogs of the pre-main sequence Sun based on 23 hours observations of 43 analogs of the young Sun in the Orion Nebula Cluster obtained with the Chandra X-ray Observatory. We find the X-ray luminosities are strongly elevated over main sequence levels with average = 30.3 erg/s and = -3. Read More

About 1000 X-ray emitting young pre-main sequence (PMS) stars distributed in mass from 0.05 to 50 solar masses are detected in an image of the Orion Nebula obtained with the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory. This is the richest field of sources ever obtained in X-ray astronomy. Read More

1998Aug
Affiliations: 1RIKEN, 2ISAS, 3ISAS, 4University of Tasmania, 5JPL, 6NASA/GSFC
Category: Astrophysics

The X-ray binary pulsar GX 1+4 was observed with Ginga every year from 1987 to 1991, and with ASCA in 1994. During the Ginga observations, GX 1+4 was in the steady spindown phase, while the X-ray flux was not steady. The X-ray luminosity decreased down to L = 2. Read More