Search Publications
Isolated neutron stars: magnetic fields, distances,and spectra
van Kerkwijk, M. H.; Kaplan, D. L.
We present timing measurements, astrometry, and high-resolution spectra of a number of nearby, thermally emitting, isolated neutron stars. We use these to infer magnetic field strengths and distances, but also encounter a number of puzzles. We discuss three specific ones in detail: (i) For RX J0720.4-3125 and RX J1308.6+2127, the characteristic ag…
The trigonometric parallax of the neutron star Geminga
Anderson, Jay; Walter, Frederick M.; Faherty, Jacqueline
We obtained a series of four observations of the isolated neutron star Geminga over an 18 month period using the Advanced Camera for Surveys (ACS) Wide Field Camera (WFC) on the Hubble Space Telescope in order to determine its trigonometric parallax. We find the parallax π=4.0±1.3 mas, corresponding to a distance to Geminga of 250
Doppler boosting, superluminal motion, and the kinematics of AGN jets
Kadler, M.; Ros, E.; Zensus, J. A. +8 more
We discuss results from a decade long program to study the fine-scale structure and the kinematics of relativistic AGN jets with the aim of better understanding the acceleration and collimation of the relativistic plasma forming AGN jets. From the observed distribution of brightness temperature, apparent velocity, flux density, time variability, a…
Ultraviolet emission from young and middle-aged pulsars: Connecting X-rays with the optical
Kargaltsev, Oleg; Pavlov, George
We present the UV spectroscopy and timing of three nearby pulsars (Vela, B0656+14 and Geminga) recently observed with the Space Telescope Imaging Spectrograph. We also review the optical and X-ray properties of these pulsars and establish their connection with the UV properties. We show that the multiwavelengths properties of neutron stars (NSs) v…
Jets from young stars
Bally, John
Most stars produce spectacular jets during their formation. There are thousands of young stars within 500 pc of the Sun and many power jets. Thus protostellar jets may be the most common type of collimated astrophysical outflow. Shocks powered by outflows excite many emission lines, exhibit a rich variety of structure, and motions with velocities …
Studies of neutron stars at optical/IR wavelengths
Motch, C.; Rea, N.; De Luca, A. +7 more
In the last years, optical studies of Isolated Neutron Stars (INSs) have expanded from the more classical rotation-powered ones to other categories, like the Anomalous X-ray Pulsars (AXPs) and the Soft Gamma-ray Repeaters (SGRs), which make up the class of the magnetars, the radio-quiet INSs with X-ray thermal emission and, more recently, the enig…
Deep Hubble space telescope ultraviolet imaging of the M87 jet
Perlman, Eric S.; Sparks, William B.; Harris, D. E. +3 more
Near-ultraviolet imaging with HST offers the best possible spatial resolution currently available for optical/UV astronomical imaging. The giant elliptical galaxy M87 hosts one of the most spectacular, best studied and nearest (d=16 Mpc) galactic-scale relativistic (synchrotron emitting plasma) jets. We have extracted from the HST archive all 220 …
Morphologies of AGN host galaxies using HST/ACS in the CDFS-GOODS field
Hasan, Priya
Using HST/ACS images in four bands F435W, F606W, F775W and F850LP, we identify optical counterparts to the X-ray sources in the Chandra Deep Field South in the GOODS South field. A detailed study has been made of these sources to study their morphological types. We use methods like decomposition of galaxy luminosity profiles, color maps and visual…
Thin magnetic hydrogen atmospheres and the neutron star RX J1856.5–3754
Ho, Wynn C. G.; Kaplan, David L.; Chang, Philip +2 more
RX J1856.5–3754 is one of the brightest nearby isolated neutron stars, and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain the data. We show that our latest models of a thin, magnetic, partially ionized hydrogen atmosphere on top of a condensed surface can fit the entire sp…
Filamentary structures in planetary nebulae
Gahm, Gösta F.; Carlqvist, Per; Dahlgren, Hanna
We have studied small-scale, filamentary features in 14 planetary nebulae and found that some structures are recurrent and shaped like the letters V and Y, with the apex or stem pointing toward the central parts of the nebula. Two such filaments containing dust, one in NGC 3132 and one in NGC 7293, were investigated in more detail. The mass and de…