Analysis of the magnetic properties experiment data on Mars: results from Mars Pathfinder

The paper presents the results of a new analysis of the data from the Magnetic Properties Experiment onboard the Mars Pathfinder Spacecraft. The spectral data from the extended visible region of material adhering to the magnets are presented as well as the time dependence of dust accumulation to the magnets. A new model is developed to estimate the magnetic properties of the accumulated dust. It is found that the optical reflection spectra of the magnetic dust differ slightly from the reflection of ground soil/dust in the vicinity of the lander. Several possible hypotheses are given to account for this difference. Magnetic dust has been removed from the magnets at least twice during the 80 sol mission by wind gusts, and it is suggested that this happens in a manner similar to sand blasting. A lower limit for the saturation magnetisation of the most magnetic particles is found to be 5 Am²/kg.     

First results from the Gauribidanur Radio heliograph

Observations of the Sun at two frequencies (51 and 77 MHz) using the East-West arm of the Gauribidanur Radio heliograph are presented.     

Early results from the Chandra X-ray observatory

We present some early results on AGN from the Chandra X-ray Observatory, highlighting high resolution spectroscopy using the High Energy Transmission Grating Spectrometer (HETGS). The quasar PKS 0637–752 was found to have a very bright X-ray jet whose shape is remarkably similar to that of the radio jet on a size scale of 100 kpc, but the X-ray emission is still inexplicably bright. Two BL Lac objects, PKS 2155–304 and Mrk 421, observed with the spectrometer were found to have no strong absorption or emission features. Other radio loud AGN observed with the HETGS show simple power law spectra without obvious features.     

Report on the solar physics-plasma physics workshop

This report summarizes the proceedings of a meeting held on 17–20 September 1974, at Stanford University. The purpose was to explore plasma physics problems which arise in the study of solar physics. Sessions were concerned with specific questions including the following: Is the solar plasma thermal or non-thermal? What spectroscopic data are required? What types of magnetic field structures exist? Do MHD instabilities occur? Do resistive or non-MHD instabilities occur? What mechanisms of particle acceleration have been proposed? What information do we have concerning shock waves? Very few questions were answered categorically but, for each question, there was discussion concerning the observational evidence, theoretical analyses, and existing or potential laboratory and numerical experiments.     

First results from the POMME survey of M31

The POMME survey (Pixel Observations of M31 with MEgacam) monitored two fields in the disc of M31 using MegaCam at CFHT over a timespan of 2.5 months in three filters (g′,r′,i′). Covering a large fraction of the disc of M31, it yields an unprecedented view on Cepheids, eclipsing binaries and microlensing events in M31. In this contribution we present the first results on the Cepheid populations in M31. Using difference imaging we detect more than 2500 Cepheids in the period range from 2 to 80 days, making the catalogue the largest and most homogeneous database of M31 Cepheids to date. The period distribution peaks at logP[day]≈0.63. We confirm the presence of a second peak in the period distribution at logP[day]≈1.13, consistent with previous findings on smaller samples, and which is also present in Galactic Cepheids, unlike those at the lower metallicities of the LMC. Using the Fourier parameters derived from light curve fitting we identify 200 first overtone pulsators among the POMME Cepheids. On-going work will include the derivation of period-luminosity relations and the extension of the analysis to eclipsing binary systems, yielding an improved distance to M31 and tighter constraints on systematics affecting the period-colour-metallicity-luminosity relations.     

Preliminary results from the spectra of V471 tauri

The findings about this unusual eclipsing variable which possesses a white-dwarf component are reported. It was found that the H and K absorption lines of Caii are strongly pressure-broadened, and exhibit two double-reversal emission components. The radial velocities derived from the central strong emission components of Caii (H and K) are in agreement with the mean radial velocity curve obtained from the metallic absorption lines of the existing elements, whereas H (4340.47 Å) does not conform with the mean radial velocity curve. In certain orbital phases the H (6562.82 Å) line occurs in emission.     

Initial results from the Madurai solar radio spectrograph

A new digital radio spectrograph, the Madurai Solar Radio Spectrograph (MSRS), has been constructed at Madurai Kamaraj University, Madurai, India, and is being operated at the Radio Astronomy Centre, Ooty in southern India to observe solar bursts in the frequency range 30–80 MHz. The operation of the new instrument is briefly described. Observations of solar bursts by this instrument and the results from the preliminary analysis are presented.     

Early science results from the Cosmic Origins Spectrograph

The Cosmic Origins Spectrograph (COS) is an ultraviolet spectrograph installed on the Hubble Space Telescope during Servicing Mission Four. COS covers 1150–3200 Å at spectral resolutions up to R～18,000. COS is the most sensitive UV spectrograph to have flown on HST. In this paper, I present science results from the first nine months of COS science operations, focusing on how COS has enabled probes of cosmic origins, from star and planet formation to the large scale structure of the modern universe.     

First results from the TGRS high-resolution GRB Spectrometer

The Transient Gamma Ray Spectrometer (TGRS) is a 215 cm³ passivelycooled germanium detector designed primarily to study spectral features of gamma ray bursts. Since shortly after its launch on 1994 Nov. 1 it has been producing high-resolution spectra of GRBs and solar flares. Some of these spectra are presented here.Although it has not yet detected any line features in GRBs-none were expected so early in the mission-several bursts have been seen simultaneously by TGRS, the Konus instruments on the same spacecraft, and the BATSE instrument on Compton GRO. A comparison of the spectra obtained by these various instruments, as presented here, may resolve the question of whether line features actually exist, and if so provide detailed spectroscopy to determine their physical origin.     

Oxidation state of the atmosphere and crust of Venus from pioneer Venus results

Recent spacecraft observations of Venus permit a detailed model of sulfur chemistry in the atmosphere-lithosphere system. Pioneer Venus experiments confirm that, as predicted, COS and H₂S are dominant over SO₂ in the lower atmosphere, and that the equilibrium concentrations of S₂ and S₃ are significant. Many criteria serve to bracket the oxidation state of the crust: it is nearly certain that the S₂^2?/SO₄^2? buffer regulates the oxygen fucagity, and that FeO is at least as abundant as Fe₂O₃ in crustal silicates. A highly oxidized crust (as, for example, would result from O₂ absorption complementary to escape of vast amounts of H₂) is incompatible with the gas-phase sulfur chemistry. If the Pioneer Venus mass spectrometer estimates of the abundance of sulfur gases are correct, Earth-like models for the bulk composition of Venus are seriously in error, and a far lower FeO content is required for Venus.     

HD 12098 and other results from Nainital-Cape Survey

Nainital-Cape Survey was started with an aim to search for new rapidly oscillating Ap stars in the northern hemisphere. We discovered one new mono-periodic roAp star HD 12098. The frequency separation of HD 12098 suggests a rotation period of 5.5 days for the star. We summarize here the observations of HD 12098 and briefly discuss the results of the multi-site observation campaign organized to resolve the ambiguity in the determination of the rotation period of HD 12098. Other interesting results like non-oscillating Ap stars discovered and two candidate stars in which roAp periodicity is seen but not confirmed are also discussed.     

Comparison of the analytical results from the surveyor,Apollo, and Luna missions

The principal chemical element composition and inferred mineralogy of the powdered lunar surface material at seven mare and one terra sites on the Moon are compared. The mare compositions are all similar to one another and comparable to those of terrestrial ocean ridge basalts except in having higher titanium and much lower sodium contents than the latter. These analyses suggest that most, if not all, lunar maria have this chemical composition and are derived from rocks with an average density of 3.19 g cm^–3. Mare Tranquillitatis differs from the other maria in having twice the titanium content of the others.The chemical composition of the single highland site studied (Surveyor 7) is distinctly different from that of any of the maria in having much lower amounts of titanium and iron and larger amounts of aluminium and calcium. Confirmation of these general characteristics of lunar highland material has come from recent observations by the Apollo 15 Orbiter. The inferred mineralogy is 45 mole percent high anorthite plagioclase and the parent rocks have an estimated density of 2.94 g cm^–3. The Surveyor 7 chemical composition is the principal contributor to present estimates of the overall chemical composition of the lunar surface.Presented at the NATO Advanced Study Institute on Lunar Studies, Patras, Greece, September 14–25, 1971. This paper is an expanded and updated version of a paper presented at the Apollo 12 Lunar Science Conference, Houston, Texas, January 11–14, 1971, and published in the Proceedings of this Conference (Turkevich, 1971).     

First results from the arcminute cosmology bolometer array receiver

We review the first science results from the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a multi-frequency millimeter-wave receiver optimized for observations of the Cosmic Microwave Background (CMB) and the Sunyaev–Zel’dovich (SZ) effect in clusters of galaxies. ACBAR was installed on the 2 m Viper telescope at the South Pole in January 2001 and the results presented here incorporate data through July 2002. We present the power spectrum of the CMB at 150 GHz over the range ℓ=150–3000 measured by ACBAR as well as estimates for the values of the cosmological parameters within the context of ΛCDM models. We find that the inclusion of Ω_Λ greatly improves the fit to the power spectrum. We also observe a slight excess of small-scale anisotropy at 150 GHz; if interpreted as power from the SZ effect of unresolved clusters, the measured signal is consistent with CBI and BIMA within the context of the SZ power spectrum models tested.     

The THU-NAOC transient survey: the performance and results from the first year

The Tsinghua University-National Astronomical Observatories, Chinese Academy of Sciences(NAOC) Transient Survey is an automatic survey that conducts a systematic exploration of optical transients. This project utilizes a 60/90 cm Schmidt telescope at the Xinglong Station of NAOC. This survey repeatedly covers ～ 1000 square degrees of the northern sky with a cadence of 3–4 d. With an exposure of 60 s,the survey reaches a limiting unfiltered magnitude of about 19.5 mag, which enables us to discover supernovae in their relatively young stages. We describe the overall performance of our survey during the first year and present some preliminary results.     

Data processing and initial results from the CE-3 Extreme Ultraviolet Camera

The Extreme Ultraviolet Camera(EUVC) onboard the Chang'e-3(CE-3)lander is used to observe the structure and dynamics of Earth's plasmasphere from the Moon. By detecting the resonance line emission of helium ions(He+) at 30.4 nm, the EUVC images the entire plasmasphere with a time resolution of 10 min and a spatial resolution of about 0.1 Earth radius(RE) in a single frame. We first present details about the data processing from EUVC and the data acquisition in the commissioning phase, and then report some initial results, which reflect the basic features of the plasmasphere well. The photon count and emission intensity of EUVC are consistent with previous observations and models, which indicate that the EUVC works normally and can provide high quality data for future studies.     

Lunar structure and dynamics - results from the apollo passive seismic experiment

Analysis of seismic signals from man-made impacts, moonquakes, and meteoroid impacts has established the presence of a lunar crust, approximately 60 km thick in the region of the Apollo seismic network; an underlying zone of nearly constant seismic velocity extending to a depth of about 1000 km, referred to as the mantle; and a lunar core, beginning at a depth of about 1000 km, in which shear waves are highly attenuated suggesting the presence of appreciable melting. Seismic velocitites in the crust reach 7 km s^–1 beneath the lower-velocity surface zone. This velocity corresponds to that expected for the gabbroic anorthosites found to predominate in the highlands, suggesting that rock of this composition is the major constituent of the lunar crust. The upper mantle velocity of about 8 km s^–1 for compressional waves corresponds to those of terrestrial olivines, pyroxenites and peridotites. The deep zone of melting may simply represent the depth at which solidus temperatures are exceeded in the lower mantle. If a silicate interior is assumed, as seems most plausible, minimum temperatures of between 1450°C and 1600°C at a depth of 1000 km are implied. The generation of deep moonquakes, which appear to be concentrated in a zone between 600 km and 1000 km deep, may now be explained as a consequence of the presence of fluids which facilitate dislocation. The preliminary estimate of meteoroid flux, based upon the statistics of seismic signals recorded from lunar impacts, is between one and three orders of magnitude lower than previous estimates from Earth-based measurements.Paper dedicated to Professor Harold C. Urey on the occasion of his 80th birthday on 29 April, 1973.