bluuebunny/crossref_metadata_2025 huggingface dataset:
Can AGN (Active Galactic Nuclei) Alone Make the Cosmic X-ray Background?
Authors: Leiter Darryl , Boldt Elihu
Published: July 2016

Recent ROSAT X-ray observations of AGN have yielded important new information about the analytic structure of the AGN X-ray luminosity function and its evolution out to z = 3. Using the luminosity evolution obtained within the cosmological context of Ω=0, we find[ that AGN could readily make up the CXB (cosmic X-ray background). However, in this case we find that accounting for the CXB with accretion-powered AGN emission is incompatible with the observed mass function for present-epoch black hole galactic nuclei (both active and dormant). On the other hand, we find that the luminosity evolution obtained with ROSAT for such AGN within the cosmological context of Ω=1 is indeed compatible with the present-epoch black hole galactic nuclei mass function. This apparently acceptable solution, though, definitely falls short of accounting for all the CXB, even when considering unified models for AGN. This difficulty can be resolved by noting that the underlying supermassive black holes which already exist at the onset of the canonical AGN phenomenon of supply-limited accretion must have undergone a previous growth phase where the accretion would be expected to be Eddington-limited. In this likely scenario (i.e., for Ω=1) the residual CXB, that over and above the foreground of canonical AGN, can be naturally explained by the characteristic X-ray emission from highly compact PAG (precursor active galaxy) sources associated with these numerous black holes, at redshifts just beyond the earliest AGN.
Gamma Rays and Jets in Active Galactic Nuclei
Authors: Meyer Donald
Published: July 2016

It will be shown that the jets observed in AGN's are the result of the high energy gamma rays recently observed by the EGRET and Whipple collaborations interacting with a medium of density typical of that expected in galaxies. All of the observed properties of the jets follow from this interaction.
3C 345: The Periods in the Optical Variability and Further Confirmation of a Connection between Optical Outbursts and Superluminal Components of Radiojet
Authors: Babadzhanyants M.K. , Belokon' E.T.
Published: July 2016

We present new results of our monitoring program for the superluminal quasar 3C 345 having been in continuous operation since 1968. The photographic B-band observations newly reported were made in 1984-91 during 218 nights. The optical light curve (1965-91) containing all available B-band observations was obtained.
Time Scale of Radio Sources Activity from the Statistical Model of Variability
Authors: Magdziarz P. , Machalski J.
Published: July 2016

The lack of a plateau in the average structure function (hereafter SF) for the complete flux-limited sample of Seielstad et al. (1983) [Fig.1] suggests that the mean time scale of radio sources variability at 10.8 GHz should be longer than the 3.8-yr time base of those observations. A comparison of the variability time scales derived from the SF analysis with those predicted by the statistical model of Magdziarz & Machalski (1993, AA, in print) [Fig.2] confirms consistency of that model. The mean time scale of variability of <τ> = 6±2 yr was found in both cases for v = 10.8 GHz.
Variability of the Ultraviolet Continuum and Emission Lines of NGC 3783
Authors: Reichert G.A.
Published: July 2016

On behalf of the International AGN Watch, I report on the results of intensive ultraviolet spectral monitoring of the Seyfert 1 galaxy NGC 3783. The nucleus of NGC 3783 was observed with the International Ultraviolet Explorer satellite on a regular basis for a total of seven months, once every 4 days for the first 172 days and once every other day for the final 50 days. Significant variability was observed in both continuum and emission-line fluxes. The light curves for the continuum fluxes exhibited two well-defined local minima or “dips,” the first lasting ≲ 20 days and the second ≲ 4 days, with additional episodes of relatively rapid flickering of approximately the same amplitude. As in the case of NGC 5548 (the only other Seyfert galaxy that has been the subject of such an intensive, sustained monitoring effort), the largest continuum variations were seen at the shortest wavelengths, so that the continuum became “harder” when brighter. The variations in the continuum occurred simultaneously at all wavelengths (Δt < 2 days). Generally, the amplitude of variability of the emission lines was lower than (or comparable to) that of the continuum. Apart from Mg II (which varied little) and N V (which is relatively weak and badly blended with Lyα) the light curves of the emission lines are very similar to the continuum light curves, in each case with a small systematic delay or “lag.” As for NGC 5548, the highest ionization lines seem to respond with shorter lags than the lower ionization lines. The lags found for NGC 3783 are considerably shorter than those obtained for NGC 5548, with values of (formally) ∼ 0 days for He II+O III], and ∼ 4 days for Lyα, and C IV. The data further suggest lags of ∼ 4 days for Si IV+O IV], and 8–30 days for Si III]+C III]. Uncertainties in these quantities are likely to be of order 2–3 days for the stronger features (Lyα, C IV), and 3–4 days for the weaker ones (He II+O III], Si IV+O IV], Si III]+C III]). Mg II lagged the 1460 Å continuum by ∼ 9 days, although this result depends on the method of measuring the line flux, and may in fact be due to variability of the underlying Fe II lines. Correlation analysis further shows that the power density spectrum contains substantial unresolved power over time scales of ≲ 2 days, and that the character of the continuum variability may change with time.
Correlated Flux Density Outbursts and Structural Variations in a Sample of Low Frequency Variable Radio Sources
Authors: Bondi M. , Padrielli L. , Fanti R. , Gregorini L. , Mantovani F. , Romney J.D. , Bartel N. , Weiler K.W. , Nicolson G.D.
Published: July 2016

Snapshot VLBI observations at 18 cm have been obtained with a global array at three epochs (1980.1, 1981.8, 1987.9) in order to investigate flux density and/or structural variations for a sample of 21 low frequency variable sources (Padrielli et al. 1987 Astron Astrophys. Suppl. Ser., 67, 63; Bondi et al. 1993 in preparation).
The Central Region of NGC 1365. SEST and VLA Observations of CO and the Radio Continuum
Authors: Sandqvist Aa. , Jörsäter S. , Lindblad P. O.
Published: July 2016

The barred spiral Seyfert galaxy NGC 1365 has been observed in the radio continuum at wavelengths of 2, 6 and 20 cm, using scaled arrays of the VLA, and complete maps have been made in the J = 1–0 and J = 2–1 CO emission lines using the SEST. MEM maps of the 6 and 20 cm emission, as well as a spectral index map, have been produced with a resolution of 2″.3 × 0″.9, and the 2-cm map has a resolution of 0″.25 ×0″.10. The dominant continuum features are a number of unresolved sources with relatively flat non-thermal spectral indices (−0.3 to −0.5), immersed in an incomplete circumnuclear ring, which is superimposed upon a background that extends into the bar along the prominent dust lanes. The ring has angular dimensions of 8″ × 20″, which corresponds to a linear dimension of the order of 1 kpc. There is clear evidence of a jet, about 5″ long, originating at the position of the Seyfert nucleus and extending in a southeastern direction, closely along the minor axis of the galaxy. The jet has a steep non-thermal spectral index (–1.0) and is aligned along the axis of a conical shell of [OIII] emission. The CO molecular gas peaks at the nucleus and is strongly concentrated to the nucleus and bar regions with a certain enhancement along the bar. The total molecular hydrogen gas mass in the observed region is 2 × 1010M⊙, with 6 × 109M⊙ lying within 2.2 kpc of the nucleus. A full presentation of the results will be published in Astronomy and Astrophysics in 1994.
Velocities Within 1 Arcsec of the Nucleus of NGC 4151 as Revealed by the HST Faint Object Camera
Authors: Catchpole R.M. , Boksenberg A. ,   The Faint Object Camera Team
Published: July 2016

We have obtained a longslit spectrum at a position angle (PA) of 84.6° and passing within 0.38 arcsec of the nucleus of NGC 4151, using the FOC f/48 camera on the Hubble Space Telescope. The spectrum shows strong emission lines including [OII] λ 3727 and [OIII] λλ 4959, 5007. By fitting with Gaussian velocity profiles, we resolve the emission lines, within 1 arcsec of the nucleus, into a high and low velocity component. The low velocity component has a total range in radial velocity of 200 km s−1 and appears to be associated with material comprising the knots seen in the FOC, F501N [O III] image of NGC 4151, illustrated in Boksenberg (1993). The much weaker high velocity system has a range of 1000 km s−1, is more smoothly distributed in brightness and shows a peak brightness close to the nucleus. Because the slit did not intersect the nucleus it is possible to determine the PA at which the two velocity systems cross the zero velocity axis. This is at PA −26° for the low velocity system and PA +32° for the high velocity system. These PA values may be subject to a systematic error as the zero velocity is defined by the mean position of the line, in the absence of any external calibration.
Modelling of Double-Peaked Emission Lines in AGN's
Authors: Nazarova L.S.
Published: July 2016

Optical spectra of the galaxies NGC3227, Mkn6, Mkn9, Mkn279, Mkn376 with double-peaked emission lines are presented. The data were obtained with the 1024-pixel TV scanner of the 6-m telescope during the 1984–1991 period. The double-peaked structure of the Hβ line in most galaxies shows changes during this period and only in the galaxy Mkn6 is the double-peaked stucture of Hβ constant. In all the galaxies except Mkn6, the blue peak of line coincides with the rest-wavelength of the line (the opposite occurs in Mkn6).
The Structure and Stability of Two-Temperature Accretion Disk
Authors: Park Myeong-Gu
Published: July 2016

The structure and stability of the two-temperature accretion disk around compact object with central soft-photon source is studied.
A Lower Limit to the Excess of Companions Among Seyfert Galaxies
Authors: Rafanelli P. , Violato M.
Published: July 2016

It is not yet clear which is the role played by interaction on Seyfert activity. Presently there are on this topic contradictory statistical results, based on the study of more or less rich samples of Seyfert galaxies. Petrosian (1982), Dahari (1985) and Mac Kenty (1989, 1990) found an excess of Seyferts among galaxies which have nearby companions and an excess of galaxies with nearby neighbors among Seyfert galaxies. The contrary result was found by Bushouse (1987) and by Fuentes Williams & Stocke (1988). In order to find more reliable conclusions, taking advantage of the increased number of Seyfert galaxies identified in the last years, we have applied the statistical procedures used by Dahari (1985) to a sample of 287 Seyfert-1 (S1) and 195 Seyfert-2 (S2) (namely to all known S1 and S2 galaxies with z ≤ 0.11 and δ ≥ −23°). A subsample has been extracted carefully excluding objects, identified as Seyfert on the basis of their morphology (e.g. on the basis of the presence of a companion) and brighter than mB = 15.5, the magnitude at which the cumulative number of S1 and S2 galaxies becomes flat. The possible companions of our Seyfert galaxies have been identified on the blue POSS prints by visual inspection looking for objects not more distant than 3 diameters from the Seyfert galaxy and not more than 3 magnitudes fainter. It results that ∼35% of both the S1 and S2 galaxies have a neighbor. This percentage is reduced to ∼14% for both classes of galaxies excluding the possible optical companions, the upper limit to the number of which has been derived starting from the counts of galaxies published by Shane and Wirtanen (1967), assuming that the probability of finding an optical companion is a Poisson probability. The same procedure applied to a control sample of 281 normal galaxies indicates that only ∼3% of the galaxies have a close companion. In conclusion Seyfert galaxies show a larger percentage (14%) of objects with companion than normal galaxies do (3%). This excess, which is the same for S1 and S2 galaxies, has been derived overestimating the number of optical companions and its value is then a lower limit.
II. The Galaxy
Authors: Roman N. G.
Published: July 2016

The region within about a kiloparsec of the sun contains no globular clusters, and few associations, planetary nebulae, novae, or Cepheids; the interpretation of 21-cm observations is complicated by peculiar motions which are comparable with galactic rotation effects. Nevertheless, this is an extremely important region for the study of galactic structure. Not only are all distance calibrations ultimately based on objects near the sun, but only in this region do we have the resolution necessary to examine the detail of galactic structure and only here can we study the numerous fainter members of the various stellar populations. As elsewhere, the problems are two-fold, the efficient selection of those objects whose study is the most informative and the choice of the methods of obtaining the greatest amount of information about those objects.
Avant - Propos
Authors: Melchior P.
Published: July 2016

Le Service International des Latitudes a été fondé par l'Association Internationale de Géodésie en 1899. Sa structure n'a pas subi de modification essentielle depuis soixante années de fonctionnement ininterrompu. Rien d'étonnant donc à ce qu'une réforme soit maintenant à l'ordre du jour. La question préoccupe à vrai dire les astronomes et les géophysiciens depuis quelques années et, si plusieurs stations ont modernisé leur équipement instrumental vers les années 1930–35, il n'en reste pas moins que l'on pourrait profiter à présent de nouveaux perfectionnements techniques dans les stations ou même y introduire des méthodes de travail nouvelles. Parallèlement le Bureau Central qui est chargé des calculs devrait être rendu plus efficace et plus rapide par l'emploi de moyens de calcul puissants qui sont aujourd'hui partout accessibles en raison de la multiplication des ordinateurs dans le monde scientifique et industriel. Cette mesure est rendue plus nécessaire encore en raison de l'augmentation du nombre de stations et aussi du légitime désir des astronomes d'essayer simultanément plusieurs procédés de calcul sur le même matériel d'observations.
Discussion of the analysis of latitudes observations
Authors: Munk Walter H.
Published: July 2016

At the present time neither the generation, now the dissipation of the Chandler Wobble is understood. These, and other problems make it most urgent from the geophysicist's point of view that the observations of latitude of the I. L. S. not only be continued, but be accelerated and improved.
The Reverse Side of the Moon
Authors: Mikhailov A. A.
Published: July 2016

During the entire time of Earth's existence the human eye has never seen the reverse side of the Moon. It is quite probable that, initially, the Moon had an axial rotation relative to the Earth, but tidal friction slowed this rotation down to such an extent that the Moon remained forever with one side turned towards the Earth.
A Study of Photographs of the Far Side of the Moon and Description of Singular Features Revealed on its Surface
Authors: Lipsky Y. X.
Published: July 2016

The third space rocket, launched in the Soviet Union on 4 October 1959, brought to the calculated orbit an automatic interplanetary station which had accomplished, for the first time in history, a flight around the Moon with the subsequent passage near the Earth. During the time of this flight, on 7 October 1959, from 18.30 to 19.10 (Moscow standard time), the photographic camera of the automatic interplanetary station (AIS) took pictures of the far side of our satellite. The camera was equipped with two objectives, having focal lengths of 200 and 500 mm. A number of papers already published [1, 2, 3] contain a detailed description of the AIS trajectory, its perturbations by the Moon, structural components of the station itself, etc.
Probable Structure and Nature of the Formations on the Reverse Side of the Moon According to Photometric Measurements of Lunar Photographs
Authors: Markov A. V.
Published: July 2016

Notwithstanding the fact that a number of defects and distortions, introduced in transmission of the images of the latter to the Earth, mar the negatives of the reverse side of the Moon, indirectly obtained on 7 October 1959 by the automatic interplanetary station (AIS), it was possible to use the photometric measurements of the secondary (terrestrial) positives of the reverse side of the Moon in the experiment of the first comparison of the characteristics of the surfaces of the visible and invisible hemispheres of the Moon.
Determination of Horizontal and Vertical Control Points for Lunar Mapping
Authors: Marchant Marvin Q.
Published: July 2016

The determination of horizontal and vertical control points has been undertaken by the Army Map Service, U.S. Army Corps of Engineers, to assure that the entire surface of the Moon which is visible from the Earth may be shown in detail and with greater accuracy than that of any existing map.
Colour and Spectral Characteristics of the Lunar Surface
Authors: Teyfel V. G.
Published: July 2016

In the broad complex of optical studies of the Moon, the most complete information which does not lead to differences of opinion is available only for the photometric characteristics of its surface. The colour and polarization characteristics of the Moon's surface have been studied in less detail; and as far as the question of the colour contrasts on the Moon's surface is concerned, no unanimity of opinion has existed until recently, since colorimetric observations conducted by various investigators have often produced contradictory results. At the same time, the question of the existence and magnitude of colour differences on the surface of the Moon is not an academic one. The colour of the lunar surface reveals just such characteristics of its physical state as do other optical characteristics—such as photometric and polarizing peculiarities which inform us about the microstructure of the surface layer of the Moon. The observed colour of the lunar formations characterizes also the external layer, which represents the result of protracted and continuous influences on the lunar surface of various external factors—such as meteorites, micrometeorites, cosmic rays, and ultraviolet, corpuscular and X-ray radiation of the Sun, etc. Differences in colour of lunar features, just as differences in the albedo, depend on the characteristics of the basic lunar rocks and not on the changes which these rocks have undergone in the course of time. Therefore, although the alteration of characteristics of the external layer of these rocks does not permit comparison of the external optical characteristics of the Moon's topography with terrestrial rocks with certainty, one can, by means of various photometric and colour data, draw a number of conclusions about the characteristics of emerging basic rocks found on its surface.
Investigation of the Polarization Properties of the Surface of the Moon
Authors: Kohan E. K.
Published: July 2016

At this time of the rapid development of cosmonautics, one of the basic problems of investigation of the Moon appears to be the problem of the matter covering the surface of the Moon. A comparison of various characterestics obtained from studies of the individual regions of the Moon with analogous characterists of terrestrial rocks led various authors [1–16] to a conclusion that the surface of the Moon is covered with a very porous substance. The mean dimensions of irregularities, as suggested by Barabashev [4] equal 2 to 5 mm, and according to Sytinskaya [2] from 0·1 mm to 10 cm. Fesenkov [17] assumes that the surface of the Moon represents a combination of relatively large grains with weak bonds between each other.
Thermal Radio Emission of the Moon at a Wave Length of 10 cm
Authors: Koshchenko V. N. , Kuzmin A. D. , Salomonovich A. E.
Published: July 2016

The investigations of intensity and phase dependence of the thermal radiation of the Moon at various wave lengths of the radio-range are very important for clarifying the properties and structure of the Moon's surface layer.
Experimental determination of absolute intensities in the solar XUV spectrum
Authors: Hinteregger H. E.
Published: July 2016

Experimental problems of absolute intensity measurements of solar electromagnetic radiation in the extreme ultra-violet (EUV) and soft X-ray region of the spectrum (designated cumulatively as “XUV” for brevity) are reviewed. From an evaluation of existing rocket and satellite data together with existing projects and goals of future observations from space vehicles, it is suggested that the numerous associated practical problems be devided into two major areas, namely (a) the general experimental art of heterochromatic absolute XUV spectrophotometry in the laboratory and (b) specific problems characteristic of the objectives of solar physics as well as existing restrictions of space technology. Within the first area (a) emphasis is placed on recent progress toward justified reliance on ionization detectors without necessary connection to source standards. For the second area (b), emphasis is placed on the immediate need to have existing exploratory observations followed by a new phase of more systematic experiments of increased accuracy.
First launching of the British stabilized Skylark rocket
Authors: Wilson R.
Published: July 2016

A brief report is given on the launching of the first Sun pointing stabilized Skylark rocket from Woomera, Australia on August 11th 1964.
The importance of absolute photometry
Authors: Heddle D. W. O.
Published: July 2016

A comparison is made between the ultraviolet stellar fluxes measured by three sets of observers. The comparison is extended to visible and near ultraviolet measurements. Absolute intensities are compared in all cases and an enhanced ultraviolet emission is noted in i Ori. The well known ultraviolet deficiency is found in other cases.
B star colours between 2000 and 3000 angstroms
Authors: Boggess Albert
Published: July 2016

Ultraviolet fluxes at 2200 and 2600 Å have been measured for about 180 B and A stars using filter photometers in rockets. Forty-eight of these stars have been observed more than once, and an analysis of these data show the uncertainty of a single observation to be less than 20 %. A U-V color versus B-V plot of luminosity class III, IV and V stars with little reddening shows a degree of correlation consistent with the observational uncertainty. The data appears to be of sufficient quality for use in deriving B star temperatures and interstellar scattering curves.
Ultraviolet emission from galaxies
Authors: Burbidge E. Margaret
Published: July 2016

The ultraviolet radiation from normal elliptical, spiral, and irregular galaxies and from abnormal objects (radio sources, quasi-stellar objects, and Seyfert galaxies) is discussed. A list of expected emission lines is compiled from previously published lists for planetary nebulae. The problem of the passage of Lyman α radiation from the source to the observer is reviewed and possible Lyman α fluxes from various types of normal and abnormal galaxies are estimated for the case that most of the Lyman α generated in the source can escape from it. The abnormal galaxies should be the stronger Lyman α emitters. Finally, it is shown that quasi-stellar radio sources in the apparent visual magnitude range 17–19 can have redshifts in the range z = 1–2, and Lyman α can come into the wavelength region accessible from the ground. To facilitate line identifications in existing spectra of such objects, ultraviolet spectra of planetary nebulae and of the relatively bright object 3C273 are greatly needed.
Infra-red spectra of stars, planets and the Moon from Stratoscope II
Authors: Woolf N. J.
Published: July 2016

Two flights of the balloon borne telescope Stratoscope II have been made for infra-red spectroscopic observations. The paper summarises the results of observing cool stars, Mars, Jupiter and the Moon.
Low frequency radio astronomical observations from rockets and satellites
Authors: Smith F. G.
Published: July 2016

Observations from space vehicles of low frequency radio waves are discussed in relation to the observations made at higher frequencies from ground based observatories. It is shown that at frequencies below about 5 MHz the radiation is primarily extragalactic in origin, and that the observed values of sky brightness are consistent with the extrapolated values.

An absorption effect observed at frequencies below 2 MHz appears to be isotropic and suggests that the Sun is at the centre of an H II region with emission measure 5 pc. cm-6. It is shown that if this region is contained in the Galaxy it will have a significant effect on the synchrotron radiation from the plane and on the rotation measure of polarisation of discrete sources.
Large Domes
Authors: Babcock H. W.
Published: July 2016

BABCOCK: On behalf of the Mt Wilson and Palomar group, I'd like to welcome all of you who braved this bad weather. We weren't quite counting on this deluge, but we will go ahead with the program as arranged.
Miscellaneous Problems
Authors: Heckmann O.
Published: July 2016

HECKMANN: I'll call on Bruce Rule to begin this session.
Part 5 LARGE DOMES
Authors: Babcock Dr H. W.
Published: July 2016

BABCOCK: On behalf of the Mt Wilson and Palomar group, I'd like to welcome all of you who braved this bad weather. We weren't quite counting on this deluge, but we will go ahead with the program as arranged.
Searching Hubble Space Telescope Images for Core-Collapse Supernova Progenitors
Authors: Van Dyk Schuyler D. , Li Weidong , Filippenko Alexei V.
Published: July 2016

Identifying the massive progenitor stars that give rise to core-collapse supernovae (SNe) is one of the main pursuits of supernova and stellar evolution studies, and is essential for understanding the birth of pulsars. Using ground-based images of recent, nearby SNe obtained primarily with the Katzman Automatic Imaging Telescope (KAIT), astrometry from 2MASS, and archival images from the Hubble Space Telescope (HST), we have attempted the direct identification of the progenitors of 16 Type II and Type Ib/c SNe. We may have identified the progenitors of the Type II SNe 1999br and 1999ev, the Type Ib SNe 2001B and 2001is, and the Type Ic SN 1999bu, possibly doubling the number of known SN progenitors. For the remaining SNe, limits placed on the absolute magnitude and color (when available) of the progenitor allows us to place limits on the progenitor's mass. Specifically, we have been able to place a relatively stringent limit on the progenitor of the Type II-P SN 2001du in NGC 1365, consistent with the limits placed on the masses of other Type II-P SNe. We have also recently identified the progenitor of the Type II-P SN 2003gd in Messier 74.
Chandler Wobble and Free Core Nutation of Neutron Stars
Authors: Gusev Alexander , Kitiashvili Irina
Published: July 2016

Extending the theory of core-mantle differential rotation of a planet, we have obtained the periods PCW and PFCN for different pulsars in the second approximation. We have investigated the dependence of these periods on the equation of state of neutron liquid, flatness of mantle and crust of the neutron star.
Supernova Remnants: An Introductory Review
Authors: Vink Jacco
Published: July 2016

The two main aspects of supernova remnant research addressed in this review are: I. What is our understanding of the progenitors of the observed remnants, and what have we learned from these remnants about supernova nucleosynthesis? II. Supernova remnants are probably the major source of cosmic rays. What are the recent advances in the observational aspects of cosmic ray acceleration in supernova remnants?
XMM-Newton Observation of SNR RX J1713.7–3946
Authors: Cassam-Chenaï G. , Decourchelle A. , Ballet J. , Sauvageot J.-L. , Dubner G.
Published: July 2016

We present the first results of the observations of the supernova remnant RX J1713.7–3946 (also known as G347.3–0.5) obtained with the EPIC instrument on board the XMM-Newton satellite. We show a 5-pointings mosaiced image of the X-ray synchrotron emission. We characterize this emission by mapping its spectral parameters (absorbing column density NH and photon index γ). The synchrotron spectrum is flat at the shock and steep in the interior of the remnant. NH is well correlated with the X-ray brightness. A strong NH is found in the southwest rim of RX J1713.7–3946. We suggest that the SNR is interacting with a HI region there.
HI Study of Southern Galactic Supernova Remnants
Authors: Koo Bon-Chul , Kang Ji-hyun , McClure-Griffiths Naomi
Published: July 2016

We briefly summarize the survey of HI 21 cm emission lines to search for shocked atomic gas associated with Galactic supernova remnants (SNRs) in the southern sky. For G347.3–0.5, we discuss the distance to the SNR and the implications of the HI results.
Supernova Remnants in the Magellanic Clouds
Authors: Filipović M. D. , Staveley-Smith L. , Reid W. , Jones P. A.
Published: July 2016

A study of the nature and the spatial distribution of over 250 discrete radio sources (HII regions and SNRs) in the Magellanic Clouds (MCs) is underway. A multi-frequency comparison of these sources involves the latest radio, IR, optical and X-ray surveys with angular resolution of <1′. Special emphasis is given to the MC SNRs. Their morphology, birth rate and overall properties are investigated and compared with Galactic SNRs and SNRs from other nearby galaxies. Also, we are investigating the radio source distribution throughout both MCs.
A Key to Pulsar Wind Bubble Morphologies: Hydrodynamical Simulations
Authors: van der Swaluw Eric , Downes Turlough P.
Published: July 2016

We present a model of a pulsar-driven supernova remnant, by using a hydrodynamics code, which simulates the evolution of a pulsar wind nebula when the pulsar is moving at a high velocity through its expanding supernova remnant. The simulation shows four different stages of the pulsar wind nebula: the supersonic expansion stage, the reverse shock interaction stage, the subsonic expansion stage and ultimately the bow shock stage. Due to the high velocity of the pulsar, the position of the pulsar is located at the head of the pulsar wind bubble, after the passage of the reverse shock. The resulting morphology of the pulsar wind bubble is therefore similar to the morphology of a bow shock pulsar wind nebulA. We show how to distinguish these two different stages, and apply this method to the SNR G327.1–1.1, for which we argue that there is no bow shock around its pulsar wind nebulA.
A Spectral Analysis of the Central Component of CTB 80
Authors: Castelletti G. , Dubner G. , Golap K. , Goss W. M.
Published: July 2016

Based on observations of the extended supernova remnant CTB 80 carried out with the Giant Metrewave Radio Telescope (GMRT, India) at 240 and 618 MHz we have analyzed the spectral behavior of the ∼ 10′ nebula formed near the pulsar PSR B1951+32, finding signatures of the interaction of the pulsar with the surrounding plasma.
Optical and Infrared Observations of Anomalous X-ray Pulsars
Authors: Durant Martin , van Kerkwijk Marten H. , Hulleman Ferdi
Published: July 2016

The detection of optical/infrared counterparts to Anomalous X-ray Pulsars (AXPs) has greatly increased our understanding of these systems. Models for the AXP phenomenon were based upon their X-ray emission, and all but the magnetar model made predictions for the optical/infrared that have now been falsified. With detections in hand, detailed studies of the optical/infrared to X-ray flux ratios, variability, and the spectral energy distributions have become possible. We present new data on two AXPs taken with Keck and Magellan, and compare the results with predictions made in the context of the magnetar model, in which the emission is due to ion currents flowing in the ≳ 1014G magnetosphere of young neutron stars.
Two Radio Pulsars with Magnetar Fields
Authors: McLaughlin M. A. , Lorimer D. R. , Lyne A. G. , Kramer M. , Faulkner A. J. , Kaspi V. M. , Stairs I. H. , Manchester R. N. , Hobbs G. , Camilo F. , Possenti A. , D'Amico N.
Published: July 2016

PSRs J1847–0130 and J1718–37184 have inferred surface dipole magnetic fields greater than those of any other known pulsars and well above the “quantum critical field” above which some models predict radio emission should not occur. These fields are similar to those of the anomalous X-ray pulsars (AXPs), which growing evidence suggests are “magnetars”. The lack of AXP-like X-ray emission from these radio pulsars (and the non-detection of radio emission from the AXPs) creates new challenges for understanding pulsar emission physics and the relationship between these classes of apparently young neutron stars.
Giant Pulses — A Brief Review
Authors: Johnston Simon , Romani Roger W.
Published: July 2016

We briefly review observational manifestations of pulsars with giant pulse emission and consider quasi-giant pulse phenomena in other pulsars. We argue that power-law statistics give the best definition of giant pulses. Finally, we speculate as to the origin of the giant pulses and a possible link with high energy emission.
Future Facilities for Gamma-Ray Pulsar Studies
Authors: Thompson D. J.
Published: July 2016

Pulsars seen at gamma-ray energies offer insight into particle acceleration to very high energies, along with information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars. During the next decade, a number of new gamma-ray facilities will become available for pulsar studies. This brief review describes the motivation for gamma-ray pulsar studies, the opportunities for such studies, and some specific discussion of the capabilities of theGamma-ray Large Area Space Telescope (GLAST)Large Area Telescope (LAT) for pulsar measurements.
Ensemble Pulsar Time Study by Pulsar Timing Observations
Authors: Yang Tinggao , Ni Guangren
Published: July 2016

Long term timing of multiple millisecond pulsars can contribute to the study of an ensemble pulsar time scale PTens. A wavelet decomposition algorithm (WDA) was applied to define a PTens using the available millisecond pulsar timing datA. The PTens obtained from WDA is more stable than those resulting from other algorithms. The Chinese 50 m radio telescope is specially designed for PTens study and detection of gravitational wave background via millisecond pulsars timing observations. A scheme for multiple millisecond pulsar timing and ensemble pulsar time study is discussed in some detail.
Spectral Analysis of Stars on Planet-Search Surveys
Authors: Fischer Debra , A. Valenti Jeff , Marcy Geoff
Published: July 2016

We present spectroscopic analysis of ∼1000 stars on the Lick, Keck and AAT planet search projects. This analysis provides a quantitative, and unbiased correlation between metallicity and the rate of occurrence of detected gas giant planets with orbital periods shorter than three years. As stellar metallicity increases, the occurrence of planets increases. Stars with [Fe/H] that is one third of solar only have gas giants detected ∼ 3% of the time. Stars with solar metallicity have a planet occurrence rate of 5 − 10%. The occurrence of gas giant planets rises to 20% in stars with a metallicity that is three times solar.

At issue is whether the quantitative dependence of planet occurrence on metallicity is primarily an initial condition, or a by-product of accretion of gas-depleted material onto the convective zone of the star. Accretion could be distinguished as the underlying mechanism for enhanced metallicity if: 1) planet-bearing F-type stars with thinner convective envelopes show a higher mean metallicity than planet-bearing G- or K-type stars, or 2) planet-bearing sub-giants with diluted convective zones showed statistically lower metallicity than their main sequence counterparts.
VINCI/VLTI Observations of Main Sequence Stars
Authors: Kervella Pierre , Thévenin Frédéric , Morel Pierre , Provost Janine , Berthomieu Gabrielle , Ségransan Damien , Queloz Didier , Bordé Pascal , Di Folco Emmanuel , Forveille Thierry
Published: July 2016

Main Sequence (MS) stars are by far the most numerous class in the Universe. They are often somewhat neglected as they are relatively quiet objects (but exceptions exist), though they bear testimony of the past and future of our Sun. An important characteristic of the MS stars, particularly the solar-type ones, is that they host the large majority of the known extrasolar planets. Moreover, at the bottom of the MS, the red M dwarfs pave the way to understanding the physics of brown dwarfs and giant planets. We have measured very precise angular diameters from recent VINCI/VLTI interferometric observations of a number of MS stars in the K band, with spectral types between A1V and M5.5V. They already cover a wide range of effective temperatures and radii. Combined with precise Hipparcos parallaxes, photometry, spectroscopy as well as the asteroseismic information available for some of these stars, the angular diameters put strong constraints on the detailed models of these stars, and therefore on the physical processes at play.
Hot Topics in the Solar System—Chandra Observations
Authors: J. Wolk Scott
Published: July 2016

In this short paper, I summarize Chandra observations of various objects in the Solar System. In addition to the Moon and several comets, Chandra has observed all the planets between Venus and Uranus. With one exception, all have been clearly detected.
Solar Gamma-Ray Line Spectroscopy – Physics of a Flaring Star
Authors: H. Share Gerald , J. Murphy Ronald
Published: July 2016

We discuss how gamma-ray spectroscopy provides information about the acceleration and transport of electrons and ions in solar flares, and their interaction with the solar atmosphere. Temporal studies illuminate differences in the acceleration and transport of electrons and ions. Nuclear line studies reveal the elemental abundance, density, and temperature of the ambient solar atmosphere; and the spectrum, composition, and directionality of the accelerated ions.
Stellar Flares and Coronal Structure
Authors: Güdel Manuel
Published: July 2016

Coronal structure and coronal heating are intimately related in magnetically active stars. Coronal structure is commonly inferred from radio interferometry and from eclipse and rotational modulation studies. We discuss to what extent flares may be responsible for coronal structure and global observable properties in magnetically active stars.
Diagnostics of Non-thermal Particles in Solar Chromospheric Flares
Authors: Fang C. , Xu Z. , Ding M. D.
Published: July 2016

Particle beam bombardment on the solar chromosphere produces non-thermal ionization and excitation. The effect on hydrogen lines is investigated by using non-LTE theory and semi-empirical flare models. It has been found that in the case of electron bombardment, the Hα line is widely broadened and enhanced. Significant enhancements at the wings of Lyα and Lyβ lines are also predicted. In the case of proton bombardment, less strong broadening and less central reversal are expected. We found that the total energy flux of the particle beam and the atmospheric condition give much influence on the line profiles, which, however, are less sensitive to the power index. Based on the Hα line profile measurement, a method to deduce the total energy flux of the particle beam is proposed.
Resolving Atmospheric Structure in V471 Tauri
Authors: M. Walter Frederick
Published: July 2016

The K2V-DA binary V471 Tau has an extended atmosphere. By using the DA white dwarf as a probe, we can probe the atmosphere along the line of sight to the white dwarf with a spatial resolution of order 10,000 km. We observe absorption lines from C II through N V in absorption against the DA photospheric continuum. The velocities are those of gas in co-rotation with the K star.
Stellar Coronal Spectroscopy with the Chandra HETGS
Authors: P. Huenemoerder David , Boroson Bram , S. Schulz Norbert , Canizares Claude R. , L. Buzasi Derek , L. Preston Heather , H. Kastner Joel
Published: July 2016

Spectroscopy with the Chandra High Energy Transmission Grating Spectrometer (HETGS) provides details on X-ray emission and activity from young and cool stars through resolution of emission lines from a variety of ions. We are beginning to see trends in activity regarding abundances, emission measures, and variability. Here we contrast spectra of TV Crt, a weak-lined T Tauri star (WTT), with TW Hya, a Classical T Tauri star (CTT). TV Crt has a spectrum more like magnetic activity driven coronae, relative to the TW Hya spectrum, which we have interpreted as due to accretion-produced X-rays. We have also observed the long period system, IM Pegasi to search for rotational modulation, and to compare activity in a long period active binary to shorter period systems and to the pre-main sequence stars. We detected no rotational modulation, but did see long-duration flares.
The Variability of Sunlike Stars on Decadal Timescales
Authors: R. Radick Richard , Lockwood G. W. , Henry G. W. , Baliunas S. L.
Published: July 2016

We have combined observations of about 30 sunlike stars from Mount Wilson, Lowell, and Fairborn Observatories to extend our joint time series from 12 to 17 years. The full range of variation on the decadal timescale has probably now been observed for most of our program stars. Statistical relationships between chromospheric and brightness variability derived earlier by us are confirmed. Young active stars become fainter as their chromospheric Ca II HK emission increases, while older less active stars such as the Sun become brighter as their HK emission increases. The Sun's photometric variation still appears somewhat small in amplitude compared to the other stars in this sample with similar mean chromospheric activity.
Influence of Planets on Parent Stars: Angular Momentum
Authors: Soker Noam
Published: July 2016

I review some possible processes by which planets and brown dwarfs can influence the evolution of their parent evolved stars. As sunlike stars evolve on the red giant branch (RGB) and then on the asymptotic giant branch (AGB), they will interact with their close planets (if exist). The interaction starts with tidal interaction: this will lead the planets to deposit most of their angular momentum to the envelope of the giant, and then spiral-in to the envelope. (Too many papers dealing with close planets [less than about 3-6 AU] around evolved stars neglect tidal interaction, hence their results are questionable.) They may spin-up their parent stars by up to several orders of magnitude. The interaction of substellar objects with evolved star may enhance the mass loss rate, mainly in the equatorial plane. Possible outcomes are: (i) Planetary systems interacting with their parent AGB star may lead to the formation of moderate elliptical planetary nebulae. (ii) RGB stars which lose more mass turn to bluer horizontal branch (HB) stars. Therefore, planets may explain the formation of blue HB stars. This may explain the presence of many blue HB stars in many globular clusters (the planets be the second parameter), and some hot HB stars in the galaxy (sdB stars). (The 8.3 days use of the Hubble Space Telescope in search of planets in a globular clusters with no blue HB stars was a wrong move.) (iii) Most known stars with planets will not form planetary nebulae, because they will lose most of their envelope already on the RGB.
A Review of the Current Status of Follow-Up Techniques to Study Known Extrasolar Planets
Authors: Charbonneau David
Published: July 2016

I present a review of observational efforts to study known extrasolar planets by methods that are complementary to the radial velocity technique. I describe the current state of attempts to detect and characterize such planets by astrometry, by reflected light, by thermal emission, by transit photometry, by atmospheric transmission spectroscopy, by planet-induced chromospheric activity, and by long-wavelength radio emission. With a few exceptions, these efforts have yielded only upper limits. Nonetheless, the diversity and vivacity of these pursuits has rapidly pushed many of these techniques into the realm where realistic models of the planets and their atmospheres can now be confronted.
Orbital Motion and Magnetic Activity in Close Binaries and Planetary Systems
Authors: Rodonò Marcello , Lanza Antonino F.
Published: July 2016

The connection between orbital period variation and magnetic activity cyclic behaviour in close binaries with late-type components is addressed by discussing recent observational studies of Algols, RS CVn's, W UMa's and CVs. A theoretical model based on the Applegate's mechanism seems capable of explaining the observed orbital period modulation in terms of cyclic changes of a gravitational quadrupole moment induced by a magnetic activity cycle affecting one of the binary components. In such a case, the study of orbital period modulations offers a promising tool to investigate hydromagnetic dynamos operating in the interior of active stars, in particular, to address the fundamental question of the interaction between rotation and magnetic fields in nonlinear dynamo regimes. Moreover, interesting applications to planetary systems with a magnetically active central star are discussed.
Outflows and Accretion in Young Stellar Objects
Authors: Calvet Nuria
Published: July 2016

Outflows in young stellar objects are powered by accretion, and ∼ 0.1 of the accreted material is lost in the outflow. Observational evidence is analyzed in the context of models for the origin of the wind. Winds in FU Ori objects are clear examples of disk winds. In Classical T Tauri stars, there is evidence for the existence of a wide angle wind at scales < 100 AU, which supports the X-wind model prediction that narrow jets are the result of density/temperature enhancement towards the axis of the system. However, recent HST observations of the DG Tau jet indicate that the opening angle of the wind is more confined than predicted by the X-wind model, in better agreement with disk wind theories.
Spatially Resolved STIS Spectroscopy of Betelgeuse's Outer Atmosphere
Authors: Lobel A. , Aufdenberg J. , Dupree A. K. , Kurucz R. L. , Stefanik R. P. , Torres G.
Published: July 2016

We present spatially resolved spectra observed with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope of the upper chromosphere and dust envelope of Betelgeuse (α Orionis, M2 Iab). In the fall of 2002 a set of five high-resolution near-UV spectra was obtained by scanning at intensity peak-up position and four off-limb target positions up to one arcsecond, using a small aperture (200 by 63 mas), to investigate the thermal conditions and flow dynamics in the outer atmosphere of this important nearby cool supergiant star.

Based on Mg ii h & k, Fe ii λ2716, C ii λ2327, and Al ii] λ2669 emission lines we provide the first evidence for the presence of warm chromospheric plasma at least 1 arcsecond away from the star at ∼40 R* (1 R*≃700 R⊙). The STIS spectra reveal that Betelgeuse's upper chromosphere extends far beyond the circumstellar Hα envelope of ∼5 R*, determined from previous ground-based imaging (Hebden et al. 1987).

The flux in the broad and self-absorbed resonance lines of Mg ii decreases by a factor of ∼700 compared to the flux at chromospheric disk center. We observe strong asymmetry changes in the Mg ii h and Si i resonance line profiles when scanning off-limb, signaling the outward acceleration of gas outflow in the upper chromosphere.

From the radial intensity distributions of Fe i and Fe ii emission lines we determine the radial non-LTE iron ionization balance. We compute that the local kinetic gas temperatures of the warm chromospheric gas component in the outer atmosphere exceed 2600 K, when assuming local gas densities of the cool gas component we determine from radiative transfer models that fit the 9.7 μm silicate dust emission feature. The spatially resolved STIS spectra directly demonstrate that warm chromospheric plasma co-exisists with cool gas in Betelgeuse's circumstellar dust envelope.