Heterodyne spectroscopy of the J = 17-16 CO line in Orion

We have obtained high-resolution spectra of the 153 micrometers J = 17-16 CO line in the BN-KL region of Orion using a laser heterodyne spectrometer. The line shows broad wings (30 km s-1 FWHM at BN) characteristic of the plateau emission as well as a narrower component probably associated with the quiescent gas in the molecular ridge. From an analysis of the plateau emission together with that observed in lower J CO transitions, we derive an excitation temperature of 180 +/- 50 K and minimum column density of 1 x 10(18) cm-2 for CO in this component, which constitutes 80% of the total integrated intensity of the J = 17-16 line near BN. The peak intensity of the narrower component observed at 0.8 km s-1 resolution increases relative to that of the plateau component toward theta 1C and away from BN, while the width decreases from 10 to 4 km s-1 (FWHM).     

Heterodyne spectroscopy of the J = 22-21 CO line in Orion

We have observed the J = 22-21 line of 12CO at 2528 GHz (118.8 micrometers) in the IRc2 region of Orion. The spectra at 0.6 km s-1 resolution show both plateau emission with FWHM approximately 35 km s-1 and a narrower component with FWHM approximately 8 km s-1. Comparison with heterodyne data of similar quality on the J = 17-16 line indicates that the broad and narrow components both originate in gas with an excitation temperature Tex approximately 600 K. The emission is consistent with the predictions of shock models in which the wide component arises from the heated outflow gas and postshock molecular material, while the narrow component comes from ambient material near the leading edge of the shock front where temperatures are high but significant acceleration has not yet occurred.     

Infrared imaging spectroscopy with micron resolution of Sutter's Mill meteorite grains

Synchrotron‐based Fourier transform infrared spectroscopy and Raman spectroscopy are applied with submicrometer spatial resolution to multiple grains of Sutter's Mill meteorite, a regolith breccia with CM1 and CM2 lithologies. The Raman and infrared active functional groups reveal the nature and distribution of organic and mineral components and confirm that SM12 reached higher metamorphism temperatures than SM2. The spatial distributions of carbonates and organic matter are negatively correlated. The spatial distributions of aliphatic organic matter and OH relative to the distributions of silicates in SM2 differ from those in SM12, supporting a hypothesis that the parent body of Sutter's Mill is a combination of multiple bodies with different origins. The high aliphatic CH₂/CH₃ ratios determined from band intensities for SM2 and SM12 grains are similar to those of IDPs and less altered carbonaceous chondrites, and they are significantly higher than those in other CM chondrites and diffuse ISM objects.     

Disc precession in the M31 dipping X-ray binary Bo 158?

We present results from three XMM–Newton observations of the M31 low mass X-ray binary (LMXB) XMMU J004314.4+410726.3 (Bo 158), spaced over 3 d in 2004 July. Bo 158 was the first dipping LMXB to be discovered in M31. Periodic intensity dips were previously seen to occur on a 2.78-h period, due to absorption in material that is raised out of the plane of the accretion disc. The report of these observations stated that the dip depth was anticorrelated with source intensity. In light of the 2004 XMM–Newton observations of Bo 158, we suggest that the dip variation is due to precession of the accretion disc. This is to be expected in LMXBs with a mass ratio ≲0.3 (period ≲4 h), as the disc reaches the 3:1 resonance with the binary companion, causing elongation and precession of the disc. A smoothed particle hydrodynamics simulation of the disc in this system shows retrograde rotation of a disc warp on a period of  ∼11 P _orb  , and prograde disc precession on a period of  29 ± 1 P _orb  . This is consistent with the observed variation in the depth of the dips. We find that the dipping behaviour is most likely to be modified by the disc precession, hence we predict that the dipping behaviour repeats on an  81 ± 3 h  cycle.     

Observations of major ionization fronts in M42 and M8

Image tube filter photographs taken in the light of the low ionization energy [Nii] and high ionization energy [Oiii] lines of the core of M42 are presented. These were taken with the 98-in. Isaac Newton telescope. The whole core of M42 appears to be a complex of ionization fronts. An [Nii] photograph of M8 also suggests that the whole of this Hii region is composed of a mass of fronts penetrating into a huge neutral region containing dust, gas and molecules.     

1300 micron continuum and C18O line mapping of the giant molecular cloud cores in Orion, W49, and W51

We present observations of the 1300 micron continuum emission and the C18O spectral-line emission from three well-studied giant molecular cloud cores: Orion, W49, and W51. The observations were obtained at the Five College Radio Astronomy Observatory, and they provide a means to examine the consistency of these two methods to trace the column density structure of molecular clouds. We find a good general correlation between the 1300 micron continuum, which traces the column density of dust, and the C18O J = 2 --> 1 line emission, which traces the column density of molecular gas, when the effects of source temperature are taken into consideration. Moreover, nominal values for the gas and dust abundances and the dust properties reproduce the observed continuum-to-line ratios. Thus, no strong C18O abundance gradients within sources has been found, and it appears that either the C18O emission lines or the submillimeter dust emission may be used to derive the mass column density within molecular clouds accurately.     

1300 micron continuum and C18O line mapping of giant molecular cloud cores. II. W3, NGC 2264, NGC 6334I, RHO Ophiuchi and S140

In this paper we present nearly simultaneous 1300 microns continuum and J = 2-1 C18O maps of the cores of five molecular clouds, W3, NGC 2264, NGC 6334I, rho Oph, and S140. The purpose of this experiment was to compare these two column density tracers. We find that dust continuum and C18O emission are equally effective tracers of column density in molecular cloud cores and give a good indication of cloud structure. When the maps are analyzed in terms of the quantity q = Q/[a rho RX(C18O)], we find that q does not vary by much more than an order of magnitude either within objects or from object to object, implying that nominal dust parameters of absorption efficiency, radius, and gas-to-dust ratio and CO abundance are on average correct in a variety of sources. We did detect source-to-source variations in q. This variation could be either in the dust-to-CO number density ratio or in grain parameters. These variations are not well correlated with total source luminosity, average or typical temperature, or total column density. The best example of this variation appears to be rho Oph where q is about a factor of 7 lower than is typically found. Our approach is analogous to the study of the A nu to CO ratio and is probably equivalent to extending this study to large A nu if the same grains are responsible for both optical opacity and far-infrared to millimeter-wave emission. There is no fundamental reason to expect A nu/NCO or q to be constant and, in fact, we have found that it is not constant in even a small source sample.     

Optical spectroscopy of novae in M 31

We report results of a spectrophotometric survey of novae in M 31. The observations were carried out using the TNG at La Palma and the 1.82 m telescope of the INAF/OAPD at Asiago observatory. Low resolution spectra of the novae, obtained mainly in the early decline phase, allow us to classify the objects following the Tololo scheme (Williams 1992) (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Nuclear line spectroscopy of solar flares

The study of nuclear line spectra from solar flares holds a rich promise for elucidating the properties of both the accelerated particles and the interaction or target region. We review the observations and the analysis of the large nuclear line rich flare which occurred near the west limb starting at 08:03 UT on 27 April, 1981. The observed spectrum from this flare contains three intense and isolated gamma-ray lines which can be analyzed in a model independent way. The measured energies are 1.628 ± 0.008, 4.430 ± 0.011, and 6.147 ± 0.022 MeV, identifying them as the de-excitation lines of ²⁰Ne (1.634 MeV), ¹²C (4.438 MeV), and ¹⁶O (6.129 MeV). Elemental abundances of the ambient gas at the site of gamma-ray line production in the solar atmosphere are deduced using these gamma-ray line observations. The resultant abundances are different from local galactic abundances which are thought to be similar to photospheric abundances.Resident Research Associate at NRL under the NRC Associateship Program.     

FTIR 2–16 micron spectroscopy of micron‐sized olivines from primitive meteorites

Abstract— Infrared spectra of mineral grains from primitive meteorites could be useful for comparison with astronomical infrared spectra since some of their grains might be similar to those formed in the planet‐forming disks around young stars or in the envelopes surrounding late‐type stars. To assess the usefulness of meteorite spectra, olivine grains separated from primitive meteorites have been analyzed using FTIR microscope techniques in the 2–16 μm wavelength range. The sub‐micron sizes of the grains made a complex preparation process necessary. Five characteristic bands were measured near 11.9, 11.2, 10.4, 10.1, and 10.0 μm. The results of 59 analyses allow the calculation of band positions for meteoritic olivines as a function of their iron and magnesium contents. Comparison of the meteoritic results with astronomical data for comets and dust around young and old stars, which exhibit bands similar to the strongest infrared bands observed in the grains (at 11.2 μm), show that the spectral resolution of the astronomical observations is too low to ascertain the exact iron and magnesium (Mg: Fe) ratio of the dust in the 8–13 μm wavelength range.     

Spectroheliograms in the Mg II line at 2795.5 Å

A rocket-borne spectroheliograph designed to take monochromatic pictures of the sun in the Mgii line at 2795.5 Å was successfully launched from White Sands Missile Range on May 20, 1968. A double ?olc birefringent filter with a spectral bandpass of 2.1 Å was used to select the proper wavelength. Pinhole photographs in the soft X-ray region were also secured in the same flight. The Mgii and X-ray photographs are compared with simultaneous Caii and Hα spectroheliograms, radiomaps at 9.1 cm and 3.3 cm, a Fraunhofer map and a magnetogram and some preliminary results are discussed.     

Emission line ratios for C III in the sun

Theoretical electron-density-sensitive C III emission line ratios are presented forR ₁ =I(2s2p ³ P – 2p ^{2 3} P)/I(2s2p ¹ P – 2p ^{2 1} S) =I(1176 Å)/I(1247 Å),R ₂ =I(2s2p ³ P – 2p ^{2 3} P)/I(2s ^{2 1} S – 2s2p ³ P ₁) =I(1176 Å)/I(1908 Å), andR ₃ =I(2s2p ¹ P – 2p ^{2 1} S)/I(2s ^{2 1} S – 2s2p ³ P ₁) =I(1247 Å)/I(1908 Å). These are significantly different from those deduced previously, principally due to the adoption of improved electron impact excitation rates in the present analysis. Electron densities deduced from the present theoretical line ratios, in conjunction with observed values ofR ₁,R ₂, andR ₃ measured from solar spectra obtained by the Naval Research Laboratory's S082B instrument on boardSkylab, are found to be generally compatible. In contrast, previous diagnostic calculations imply electron densities fromR ₁,R ₂, andR ₃ that differ by up to two orders of magnitude. These results provide observational support for the accuracy of the atomic physics adopted in the present calculations, and the methods employed in the derivation of the theoretical line ratios.     

Echelle spectroscopy of narrow line regions of Seyfert galaxies

Preliminary results of spectroscopic studies of selected Seyfert galaxies employing a new Cassegrain echelle spectrograph completed at ESO are presented. Subjects reported are the asymmetric profiles of narrow emission lines, spatial variation of narrow emission line profiles, and the interstellar absorption lines.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Multi-object spectroscopy of the field surrounding PKS 2126−158: discovery of a z= 0.66 galaxy group

The high-redshift radio-loud quasar PKS 2126−158 is found to have a large number of red galaxies in close apparent proximity. We use the Gemini Multi-Object Spectrograph (GMOS) on Gemini South to obtain optical spectra for a large fraction of these sources. We show that there is a group of galaxies at   z ∼ 0.66  , coincident with a metal-line absorption system seen in the quasar's optical spectrum. The multiplexing capabilities of GMOS also allow us to measure redshifts of many foreground galaxies in the field surrounding the quasar.
The galaxy group has five confirmed members, and a further four fainter galaxies are possibly associated. All confirmed members exhibit early-type galaxy spectra, a rare situation for a Mg  ii absorbing system. We discuss the relationship of this group to the absorbing gas, and the possibility of gravitational lensing of the quasar due to the intervening galaxies.     

Trapped line radiation in X-ray sources of Population II

We suggest that an X-ray source of Population II is produced by gas accreting onto a collapsed star from an extended quasi-transparent envelope formed in the distant past in a collision with a normal star. Most of the envelope is only weakly ionized; energy balance and hydrostatic equilibrium are ensured mainly by secondary line radiation, which is trapped there for very long times before it escapes or is reabsorbed. However, in the fully ionized innermost regions of the envelope the atomic particles that can absorb and re-emit line radiation are not present and matter is steadily accreting onto the black hole, producing the primary X-rays.On the basis of the mechanism that controls the escape of line photons, we distinguish between lines of the first and second kind. The first should fall in the visible or the infrared and appear in emission; the second, resulting exclusively from allowed transitions, should fall in the ultraviolet and appear as very broad absorption lines. Heat deposited by partial absorption of X-rays is withdrawn by radiation of the first kind; hydrostatic equilibrium is ensured primarily by that of the second.The collapsed star is probably a moderately massive (10M ) black hole.     

Using slitless spectroscopy to study the kinematics of the planetary nebula population in M94

The planetary nebula populations of relatively nearby galaxies can be easily observed and provide both a distance estimate and a tool with which dynamical information can be obtained. Usually the requisite radial velocities are obtained by multi-object spectroscopy once the planetary nebulae have been located by direct imaging. Here we report on a technique for measuring planetary nebula kinematics using the double-beam ISIS spectrograph at the William Herschel Telescope in a novel slitless mode, which enables the detection and radial velocity measurements to be combined into a single step. The results on our first target, the Sab galaxy NGC 4736, allow the velocity dispersion of the stellar population in a disc galaxy to be traced out to four scalelengths for the first time and are consistent with a simple isothermal sheet model.