bluuebunny/crossref_metadata_2025 huggingface dataset:
Extended X-Ray Emission from Planetary Nebulae
Authors: Kreysing H.C. , Diesch C. , Zweigle J. , Staubert R. , Grewing M.
Published: June 2019

We present first results from the ROSAT All Sky Survey on X-ray emission of planetary nebulae (PNe). For the first time extended X-ray emission from PNe was detected. This is the case for NGC 6543, NGC 6853, A 12, NGC 4361 (and LoTr 5). X-ray emission compatible with a point source was detected from BD+30°3639, however, the spectral distribution of the X-ray photons is leading to temperatures beyond 2 106 K. Thus in all cases, with the possible exception of LoTr 5, the central star of the PNe can be excluded as the main source of the observed X-ray emission. X-ray images and ROSAT spectra for all detected PNe are presented. The best observed PN in X-ray emission is NGC 6543. Due to the close vicinity to the north ecliptic pole, this object was regularly observed, every 90 minutes during the whole half year of the ROSAT All Sky Survey, resulting in 41 ksec of integration time. In addition NGC 6543 was observed in a 50 ksec pointed observation to the north ecliptic pole, taken in June 1990 during the calibration phase (Kreysing et al. 1992). A comparison of the semi-ring-like distribution of the X-ray emission of NGC 6543 with optical CCD-images shows, that most of the X-ray emission seems to originate from the boundary region between the nebula and the halo. Neither the central star nor the hot wind from the central star wind is the main source of the X-ray emission, as proposed by the interacting stellar wind model (Kwok 1982). An alternative model employing a possible coronal heating mechanism has been discussed by Kreysing (1992); accoustic waves, travelling outward from the nebula, encounter a sudden density decline at the boundary to the halo. As a consequence the waves degenerate into shock waves, dissipating their energy in a thin region of only some 1015 cm into the ambient medium.
Mid-IR (8–13μM) Images of Planetary Nebulae
Authors: Meixner M. , Arens J.F. , Jernigan J.G. , Ball J.R. , Skinner C.J.
Published: June 2019

We present mid-IR (8–13μm) images of dust in six young planetary nebulae: IC 418, IRAS 21282+5050, NGC 6790, M4-18, M2-9 and IC 5117. The images were taken at UKIRT and the IRTF with the Berkeley mid-IR camera which was developed at the Space Sci. Lab. in UC Berkeley and is supported by IGPP and LEA, LLNL. In IC418, M2-9 and IRAS 21282, the spatial distributions of dust and of ionized gas are measurably different. In M4-18, IC5117 and NGC 6790 the spatial distributions are similar, so apparently the dust and the gas are well mixed. Spatial resolution is the key to discerning the differences in the gas and dust morphologies, and in 2 of the 3 cases where the spatial distributions appear similar, higher resolution may reveal differences. For example, we can discern that the [NeII] peaks further out than the SiC in IC 418 because it is so close and thus large in angular size compared to our ∼ 0.″ 8 resolution. In IRAS 21282+5050, we have compared the spatial distribution of the different features attributed to Polycyclic Aromatic Hydrocarbons to the dust continuum (Fig.1). Our data shows that while the 8.5 and 11.3 μm emission peaks outside the 10μm dust continuum, the 12.5μm emission is spatially coincident with it. Hence, not all PAH emission peaks outside of the dust continuum. The plateau emission, sampled by our 12.5μm band, arises from smaller PAHs than the size that causes the 11.3μm PAH feature. Thus, one interpretation of our observations is that the grain size distribution changes with radius: smaller PAHs in the center, increasing size with radius.
The Spatio-Kinematic Structure of the CO Envelopes in Evolved Planetary Nebulae
Authors: Bachiller R. , Huggins P.J. , Cox P. , Forveille T.
Published: June 2019

We report high angular resolution mapping of the CO (J=2→1 and 1→0) lines in three evolved planetary nebulae (PNe): NGC 6781, NGC 6772, and VV47. The CO 2→1 observations of the ring-like nebula NGC 6781 provide the most detailed map to date of the kinematic structure of a PN envelope. The data are well explained with a model consisting of a thin, clumpy, ellipsoidal shell, which is open at the ends and is expanding with a velocity proportional to distance from the star. The molecular shell of NGC 6772 appears similar, but the gas is more confined to an equatorial ring and is much more incomplete. The molecular gas in VV 47 is in two clumpy lobes, which are likely to be the only surviving molecular condensations from an earlier, more extended equatorial distribution of the same kind. The average CO excitation temperature of these PNe is found to be >23 K from the CO 2→1/1→0 line ratio, and the mass of molecular gas is estimated to be 0.1, 0.02, and 0.002 M⊙ in NGC 6781, NGC 6772, and VV 47, respectively. It appears that the ring-like PNe are formed from the dissociation and ionization of neutral ellipsoidal shells; destruction of the envelope begins with the rapid ionization of the least dense polar caps, and continues until the densest molecular material at the nebular waist is fully ionized.
Interaction of Planetary Nebulae by the Interstellar Medium
Authors: Borkowski K.J.
Published: June 2019

Interaction of planetary nebulae (PNe) with the interstellar medium (ISM) is quite common, in accord with our understanding of the large-scale structure of the ISM. The characteristic signature of the interaction is a dipole asymmetry resulting from a distortion and compression of the nebula in the direction of stellar motion. Studies of interacting PNe provide us with information on the structure of the ISM, and on the evolution of old PNe and PN halos.
Mid-IR Spectra of AGB and Post-AGB Stars
Authors: Skinner C. J. , Barlow M. J. , Justtanont K. , Sylvester R. J.
Published: June 2019

We have generated models of complete nova energy distributions, including the effects of the nova dust shell emission and absorption. In order to account for the dust, we require optical constants throughout the UV and EUV. Draine & Lee (1984) is the only source of such data for silicates. However, their ‘astronomical silicate’ has a strong resonance in the UV which causes circumnova dust to be heated far above its sublimation temperature in our models of Nova Her 1991. We have therefore recalculated the silicate optical constants, using the Kramers-Kronig relations, including a λ−1.0 far-IR dependence and improved 9.7μm feature, and decreasing the UV and EUV efficiencies of the grains. With these new silicate constants we can reproduce the observed behaviour of the dust shell in Nova Her 1991. Since our optical constants are consistent with the behaviour of Nova Her 1991, an EUV source, they should also be appropriate for the treatment of PN.
Mechanisms for Radio Continuum Emission of Long-Period Variable Stars
Authors: Rudnitskij G. M.
Published: June 2019

The radio continuum emission of long-period variables (LPVs) in the continuum is considered. For some LPVs (e.g., R Aql and V Hya) weak emission, observed at centimeter wavelengths, can be explained by thermal free-free radiation of the ionized gas behind the shock front in the stellar atmosphere. The ionized layer behind the shock remains optically thick at the wavelengths as short as 1 cm; the brightness temperature found for R Aql at 2 cm by Drake et al. (1987, AJ, 94, 1280), Tb = 18000 K, is consistent with the expected temperature behind the shock.
The Molecular Features in the Optical Spectra of the Proto-Planetary Nebulae
Authors: Hu J.Y.
Published: June 2019

An AGB star evolves into the proto-planetary nebula(PPN) phase, when the stellar surface temperature is hotter than 5000K(Schonberner, 1983). But the remnant of AGB dust/gas envelope is still thick in the early stages of PPN evolution. The observed optical spectrum of PPN is a spectrum of central star(T∗ hotter than 5000K, the spectral type earlier than G5) overlaped with molecular features formed by molecules in the envelope. The features are changing during the envelope turns to optical thin. Based on our systematic observations of IRAS selected PPN candidates(Hu et al. 1990) we found that molecular features in the spectra evolve as following:

1.

When object just exposes from dust shell, the column density of molecules in the envelope is very high. The molecular absorption bands are dominant in the spectra, which are resemble to the M supergiant. There are 6 objects from our 62 PPN candidates sample in this stage.

2.

When column density of molecules decreases, the spectra mainly show F-(or G-)type supergiant features from photosphere and partly also from envelope (especially the neutral atomic lines). But we still can detect the molecular bands such as C2, CN in the spectra of carbon-rich objects(3 objects in our sample, IRAS23304+6147, 20000+3239 and 19477+2401), TiO of oxygenrich object(one object, IRAS20406+2953), and ZrO and LaO of S-type transit object(one object, IRAS19454+2920).

3.

The evelope becomes optical thin and molecules absorb photons from central star then radiate by fluorescence process. In the spectrum apear the molecular emission bands resemble to the cometary spectra. A well known object in which spectrum C2 Swan bands in emission is CRL 2688(Crampton et al. 1975). We found another object, IRAS14429-4539, in the sample showing similar features.
Visual Extinction and Physical Conditions in the Bipolar Nebula M2-9
Authors: Riera A.
Published: June 2019

A detailed analysis of the visual extinction and physical conditions of the extreme bipolar nebula M2-9 has been made from optical spectra acquired with the Intermediate Dispersion Spectrograph of the 2.5m Isaac Newton Telescope (Observatorio del Roque de los Muchachos, La Palma) in combination with a 235mm camera and the IPCS detector covering the spectral range 3500-7500 Å with spectral resolution of 4 Å.
New Calculations of Thermal Pulses and s–Process Nucleosynthesis in Agb Stars
Authors: Busso M. , Chieffi A. , Gallino R. , Limongi M. , Raiteri C. M. , Straniero O.
Published: June 2019

A set of thermal pulse models was computed, for initial stellar masses extending from low (M=1.5, 3 M⊙) to intermediate (M=5, 7 M⊙), using the FRANEC evolutionary code and assuming standard mass loss and solar metallicity. The main features are: i) the third dredge–up is naturally found, even for core masses below 0.7–0.8 M⊙; ii) before the dredge–up occurrence, the main characteristics of the models (convective shell mass, interpulse duration, overlapping between adjacent pulses) are determined solely by the core mass MH, well reproducing a behaviour which is typical in the current literature (see e.g. Schonberner, 1979): in particular, the shell mass is a decreasing function of MH; iii) after dredge–up is started, the evolutionary track is modified and the strength of the pulses is enhanced; iv) the amount of dredge–up increases in time, from ≃ 10−4 M⊙ to ≃ 10−3 M⊙.
Kinematical Studies of Planetary Nebulae using Taurus+CCD
Authors: Sahu K.C. , Walsh J.R. , Walton N.A. , Pottasch S.R.
Published: June 2019

TAURUS, the imaging Fabry-Perot spectrometer, using a CCD detector, has been commissioned on the 4.2m William Herschel Telescope, creating a powerful tool for studying the kinematics of emission line objects such as planetary nebulae. The mode of operation when using a CCD is different to that with IPCS (where rapid scanning is employed), so that account has to be taken of changes in atmospheric transmission between CCD readouts. The large dynamic range of the CCD (>200) allows the simultaneous study of the line profiles from the right and faint parts of the nebulae.
Interaction of Planetary Nebulae by Prenebulae Debris
Authors: Fierro Julieta
Published: June 2019

In the present poster we suggest that some of the structures observed in the envelopes of planetary nebulae are caused by the interaction of central star wind and radiation with preplanetary nebula debris: planets, moons, minor objects, ring and ring arcs.
Circumstellar Nebular Lines in the Optical Spectrum of SN 1987A
Authors: Khan Iftikharuddin , Duerbeck Hilmar W.
Published: June 2019

The nebulosities surrounding SN 1987A have a morphological structure strongly resembling some planetary nebulae (e.g. NGC 2392, NGC 3242).
Evolutionary Tracks
Authors: Schönberner Detlef
Published: June 2019

It is now accepted without any doubts that the central stars of Planetary Nebulae (CPN) are rapidly evolving objects in the transition from the asymptotic giant branch (AGB) to the white-dwarf regime. After the pioneering study of Paczyński (1971) it has been demonstrated by Schönberner (1981) that Paczyński's calculations are too crude for the understanding of post-AGB evolution because the latter depends very sensitively on the detailed internal stellar structure, i.e. on the past AGB evolution. More precisely, the evolution of an AGB remnant is a function of the thermal-pulse cycle phase ϕ during which this remnant has been created by the planetary-nebula (PN) formation process. This has been shown by Schönberner (1979, 1983) and later fully been explored by Iben (1984).
A Search for Pulsations in O VI Planetary Nuclei
Authors: Bond Howard E. , Ciardullo Robin
Published: June 2019

The first two pulsating central stars of planetary nebulae to be discovered were those of K 1–16 (Grauer & Bond 1984) and Lo 4 (Bond & Meakes 1990). They are nonradial, multiperiodic g-mode pulsators, with typical periods near 25–31 min. They are O VI nuclei or related objects, with extremely high temperatures (Teff ≳ 100,000 K), hydrogen deficiency, and high abundances of C and O.
Distribution of Planetary Nebulae Perpendicular to the Disk
Authors: Mallik D.C.V. , Chatterjee S.
Published: June 2019

From an analytical solution to the Boltzmann-Poisson equations for a thin, vertically isothermal self-gravitating disk with the assumptions that the mass spectrum of stars is expressible as an inverse power-law and the velocity dispersion perpendicular to the plane follows a law of the form we have obtained a vertical height distribution of planetary nebulae: where being the potential at z. Figure 1 shows a normalised height distribution for various values of V0 where we have assumed a Salpeter slope, a ρ(o) = 0.10M⊙pc−3 and set m∗ = ml = 1.0m⊙. Figure 2 shows filled circles obtained from the observational sample of Daub (1982, ApJ 260, 612) superposed on the theoretical distributions. Although there is agreement for large values of z, closer to the plane the observational sample falls below the theoretical curves. Since the observational sample is size-limited, we may be missing a larger fraction of small nebulae closer to the plane. It is also possible a single value of Vo is not a correct representation of reality as these nebulae originate from stars of greatly differing ages and Vo may have changed over the lifetime of the Galactic disk.
Spectrophotometry of Selected Planetary Nebulae of Type I in the Magellanic Clouds
Authors: Torres-Peimbert S. , Peimbert M. , Ruitz M.T. , Peña M.
Published: June 2019

We carried out spectroscopic observations of N67 (in the SMC), and N66, N97 and N102 (in the LMC) with the 4-m telescope of CTIO. The wavelength range is λλ 3500–7400. From these we obtained physical conditions and chemical abundances of these objects.
UV Radiation in Different Stellar Systems
Authors: Buccino A. P. , Mauas P. J. D. , Lemarchand G.A.
Published: June 2019

We have studied the UV radiation in the range 180 to 330 nm emitted by several stars with planetary systems, in order to determine the constraints on the habitable zones posed by the radiation levels. The observations were taken from the International Ultraviolet Explorer (IUE) and the Hubble Space Telescope (HST) satellites database. The stellar sample was chosen to cover the range of what are usually called solar-type stars, from late F to K stars. We found that the planets discovered around Epsilon Eridani and 16 Cyg B are within both the optical and UV habitable zones.
Atmospheres of Extra-solar Planets and Brown Dwarfs
Authors: Allard France , Barman Travis S.
Published: June 2019

Brown dwarfs have masses intermediate to stars and planets, but their atmospheres can span planetary plasma conditions as they cool over time. They are more directly observable than the currently known extra-solar planets. In this paper, we provide a brief summary of the atmospheric properties of brown dwarfs, and apply this knowledge to predict the thermal and spectral properties of extra-solar planets.
What can Rapid Terrestrial Biogenesis Tell Us about Life in the Universe?
Authors: Lineweaver Charles H. , Davis Tamara M.
Published: June 2019

It is sometimes asserted that the rapidity of biogenesis on Earth suggests that life is common in the Universe. We critically examine the assumptions inherent in this argument. Using a lottery model for biogenesis in the Universe, we convert the observational constraints on the rapidity of biogenesis on Earth into constraints on the probability of biogenesis on other terrestrial planets. For example, if terrestrial biogenesis took less than 200 Myr (and we assume that it could have taken 1 billion years) then we find the probability of biogenesis on terrestrial planets older than ∼ 1 Gyr, is > 36% at the 95% confidence level. However, there are assumptions and selection effects that complicate this result: although we correct the analysis for the fact that biogenesis is a prerequisite for our existence, our result depends on the plausible assumption that rapid biogenesis is not such a prerequisite.
Migration Processes and Volatiles Delivery
Authors: Marov Mikhail , Ipatov Sergei
Published: June 2019

Migration processes of comets and asteroids from the outer regions of the solar system, including the Edgeworth–Kuiper belt, are regarded as important mechanisms for the formation and evolution of the inner planets. These minor bodies may be responsible for the delivery of volatile matter to the inner planets and thus be responsible for the origin of life. We estimate that the cumulative mass of icy comets impacting on the Earth during the formation of the giant planets is similar to the mass of water in the Earth oceans, and that Mars acquired more water per unit planet mass than Earth. We find that these cometary objects mostly evolved from typical near-Earth orbits and Encke-type orbits with aphelia located inside the orbit of Jupiter, and played a greater role than those with Jupiter-crossing orbits. The relative importance of comets and chondrites in the delivery of volatiles is constrained by the observed fractionation patterns of atmospheric noble gas abundance.
Search for Extraterrestrial Intelligence at 22 GHz with the Very Large Array
Authors: Shirai Toshimichi , Oyama Tomoaki , Imai Hiroshi , Abe Shinsuke
Published: June 2019

We have conducted a direct Search for Extraterrestrial Intelligence at the Water Maser frequency, 22.235 GHz, using the Very Large Array. The targets were 13 solar-type stars that were known to host exoplanetary systems. In all cases, the RMS limits of the flux density, 20 mJy (5σ), were sufficient to rule out any omnidirectional transmitters of the same power as terrestrial radars (5 × 1012 W). We discuss the significance of this non-detection.
First Year WMAP Observations
Authors: Bennett C. L.
Published: June 2019

The results of the first year WMAP sky survey are full sky microwave maps in five frequency bands from 23 to 94 GHz. Calibration errors are < 0.5% and the low systematic error level is well specified. The cosmic microwave background (CMB) is separated from the foregrounds using the multifrequency data. The 2 ≤ l ≤ 900 anisotropy power spectrum is cosmic variance limited for l < 354 with a signal-to-noise ratio >1 per mode to l = 658. The temperature-polarization cross-power spectrum reveals both acoustic features and a large angle correlation from reionization. The optical depth of reionization is τ = 0.17 ± 0.04. A best-fit cosmological model to the CMB and other measures of large scale structure works remarkably well with only a few parameters. The age of the best-fit universe is t0 = 13.7 ± 0.2 Gyr old. The matter density is Ωmh2 = 0.135+0.008--0.009, the baryon density is Ωbh2 = 0.0224 ± 0.0009, and the total mass-energy of the universe is Ωtot = 1.02±0.02. For WMAP data alone, ns = 0.99 ± 0.04. The lack of CMB fluctuation power on the largest angular scales reported by COBE and confirmed by WMAP is intriguing. WMAP continues to operate, so results will improve.
Maps of the Millimetre Sky from the BOOMERanG Experiment
Authors: de Bernardis P. , De Troia G. , Giacometti M. , Iacoangeli A. , Masi S. , Melchiorri A. , Nati F. , Piacentini F. , Polenta G. , Ricciardi S. , Ade P. A. R. , Mauskopf P. D. , Balbi A. , Cabella P. , De Gasperis G. , Natoli P. , Vittorio N. , Bock J. J. , Bond J. R. , Contaldi C. R. , Borrill J. , Boscaleri A. , Pascale E. , Jones W. C. , Lange A. E. , Mason P. , Hristov V. V. , Crill B. P. , De-Oliveira Costa A. , Tegmark M. , Ganga K. , Hivon E. , Montroy T. , Kisner T. , Ruhl J. E. , Jaffe A. H. , MacTavish C. , Netterfield C. B. , Pogosyan D. , Prunet S. , Romeo G.
Published: June 2019

In the 1998-99 flight, BOOMERanG has produced maps of ∼4% of the sky at high Galactic latitudes, at frequencies of 90, 150, 240 and 410 GHz, with resolution ≳ 10'. The faint structure of the Cosmic Microwave Background at horizon and sub-horizon scales is evident in these maps. These maps compare well to the maps recently obtained at lower frequencies by the WMAP experiment. Here we compare the amplitude and morphology of the structures observed in the two sets of maps. We also outline the polarization sensitive version of BOOMERanG, which was flown early this year to measure the linear polarization of the microwave sky at 150, 240 and 350 GHz.
Cosmological Parameters from Eigenmode Analysis of Sloan Digital Sky Survey Galaxy Redshifts
Authors: Szalay Alexander , Pope Adrian , Matsubara Takahiko , Blanton Michael R. , Eisenstein Daniel J. , Gray Jim , Jain Bhuvnesh ,   SDSS Collaboration
Published: June 2019

We present estimates of cosmological parameters from the application of the Karhunen-Loève transform to the analysis of the 3D power spectrum of density fluctuations using Sloan Digital Sky Survey galaxy redshifts. We use Ωmh and fb = Ωb/Ωm to describe the shape of the power spectrum, σL8g for the (linearly extrapolated) normalization, and β to parametrize linear theory redshift space distortions. on scales k ≤ 0.16hMpc--1, our maximum likelihood values are Ωmh = 0.264 ± 0.043, fb = 0.286 ± 0.065, σL8g = 0.966 ± 0.048, and β = 0.45 ± 0.12. When we take a prior on Ωb from WMAP, we find Ωmh = 0.207 ± 0.030, which is in excellent agreement with WMAP and 2dF. This indicates that we have reasonably measured the gross shape of the power spectrum but we have difficulty breaking the degeneracy between and Ωmh and fb because the baryon oscillations are not resolved in the current spectroscopic survey window function.
The 6dF Galaxy Survey: Mass and Motions in the Local Universe
Authors: Colless Matthew , Jones Heath , Campbell Lachlan , Burkey Daniel , Taylor Andy , Saunders Will
Published: June 2019

The 6dF Galaxy Survey will provide 167 000 redshifts and about 15000 peculiar velocities for galaxies over most of the southern sky out to about cz = 30000 km s--1. The survey is currently almost half complete, with the final observations due in mid-2005. An initial data release was made public in December 2002; the first third of the dataset will be released at the end of 2003, with the remaining thirds being released at the end of 2004 and 2005. The status of the survey, the survey database and other relevant information can be obtained from the 6dFGS web site at http://www.mso.anu.edu.au/6dFGS.

In terms of constraining cosmological parameters, combining the 6dFGS redshift and peculiar velocity surveys will allow us to: (1) break the degeneracy between the redshift-space distortion parameter β = Ω0.6m/b and the galaxy-mass correlation parameter rg; (2) measure the four parameters Ag, Γ, β and rg with precisions of between 1% and 3%; (3) measure the variation of rg and b with scale to within a few percent over a wide range of scales.
The Galaxy Evolution Explorer - Early Data
Authors: Martin Christopher ,   GALEX Team
Published: June 2019

We report on early data from the Galaxy Evolution Explorer (GALEX), a NASA Explorer Mission launched on April 28, with a nominal mission start of June 19. GALEX is performing the first space UV sky-survey, including imaging and grism surveys in two bands (1350–1750 Å and 1750–2800 Å). The surveys include an all-sky imaging survey (limit AB∼20–21), a medium imaging survey of 1000 sq. deg (limit AB∼23.5), a deep imaging survey of 100 deg2 (limit AB∼25.5), and a nearby galaxy survey. Spectroscopic grism surveys (R=100–300) will be performed with various depths and sky coverage. Many targets overlap existing or planned surveys, including SDSS, DEEP, NOAODWS, VIRMOS, SWIRE, SINGS, SIRTF-GTO, Chandra, and HST/ACS. We will use the measured UV properties of local galaxies, along with corollary observations, to calibrate the UV-global star formation rate relationship in galaxies. We will apply this calibration to distant galaxies discovered in the deep imaging and spectroscopic surveys to map the history of star formation in the universe over the redshift range 0<z<2. The GALEX mission will include a Guest Investigator program for primary observations and supporting data analysis. This will support a wide variety of investigations made possible by the first UV sky survey.
Chandra and FUSE View of the WHIM: the Local Group and Beyond
Authors: Nicastro Fabrizio
Published: June 2019

In this contribution, I review the current observational evidence for the existence of filaments of Warm-Hot Intergalactic Medium (WHIM). In particular, I first focus on the controversial issue of the identification of the z ∼ 0 highly ionized far-ultraviolet (i.e. OVI) and X-ray (i.e. OVII, OVIII and NeIX) absorbers with either a very tenuous and diffuse WHIM filament, or with much denser condensations of material at large distances in the Galactic halo. I then present our recent detection (confidence level > 3σ) of the OVII WHIM at z > 0 and derive an estimate of the total number of baryons contained in this hard-to-detect phase of the IGM.
First Science Results from the DEIMOS/DEEP2 Redshift Survey
Authors: Koo David C. ,   for the DEEP Team
Published: June 2019

DEEP2 is a major new Keck spectroscopic survey of 50,000 galaxies that aims to provide a detailed map of the cosmos at redshift z ∼ 1. We present an overview of DEEP2 and its relation to DEEP and its predecessor (DEEP1) in terms of science goals, of the instrument DEIMOS that enables completion of this survey in only a few years, and of the current status of the project. First science projects that use the first 10% of the survey data and their early results are highlighted.
Diffuse molecular clouds at high galactic latitude
Authors: Stark Ronald
Published: June 2019

The IRAS 60 and 100 μm flux from cirrus clouds are commonly explained by dust continuum emission. But this explanation in some cases requires unexpectedly high dust temperatures.

We argue that the contribution of fine structure emission of neutral oxygen, O°(63 μm), can be significant in the IRAS 60 μm band. The 0°(63 μm) line emission together with the dust continuum emission offers a plausible explanation of the observed flux ratio I(60)/I(100), as well as of its variation across individual clouds. We also discuss the clumpy/filamentary structure of these clouds.
Magnetic fields in dense regions
Authors: Heiles Carl , Goodman Alyssa A. , McKee Christopher F. , Zweibel Ellen G.
Published: June 2019

This paper concentrates on reviewing magnetic fields in dense regions; see Heiles (1988, 90) for a review of fields in diffuse regions. The past few years have increased our observational knowledge of magnetic fields in dense regions by an enormous factor—not because there are many measurements, but because we started from zero. The observable is polarization, which is small and subject to systematic errors. The fact that the advances have occurred only recently is a result of several factors: technological development; the interest and commitment of experimentally-minded astronomers; and the maturing of molecular and infrared astronomy to the point that really new results require either new insights or more difficult techniques.
Dynamical conditions of dense clumps in dark clouds: a strategy for elucidation
Authors: Prasad Sheo S.
Published: June 2019

Chemical considerations and simplified dynamical modeling suggest that dark cloud cores may be incessantly evolving such that the time spent at high core densities decreases as the density increases. After reaching a high density, gravitationally contracting dark cloud cores may either form stars or expand to states of lower densities. Cloud mass and initial density are amongst the factors that may control the evolutionary fate of the core. This view is diametrically opposite of the common belief that dense cores may be in near mechanical equilibrium. Mutually consistent end-to-end modeling of the spectral line profiles and intensities is needed to discern the reality.
The development of modes of thermal instability in a non-stationary medium (production of OH maser condensations)
Authors: Burdyuzha V. V.
Published: June 2019

In a nonstationary medium (behind the shock front, for instance) the development of isobaric and adiabatic modes of the thermal instability are more preferable. Some examples of the fragmentation of the medium on clouds in case of OH masers are given.
Symposium Summary: Fragmentation and Star Formation in Molecular Clouds
Authors: Glassgold A. E.
Published: June 2019

This Symposium on fragmentation and star formation has dealt with the heart of the study of molecular clouds, which is how they form stars. This problem is one of the most profound and challenging problems in all of astrophysics. The complexity of the interstellar medium adds to its difficulty and we cannot expect a quick and easy solution. Nonetheless, the reports presented at this Symposium indicate that substantial progress is being made in this field.
A multi-transition and multi-isotope study of CO in the giant molecular cloud Orion-A
Authors: Dutrey A. , Castets A. , Duvert G. , Bally J. , Langer W. D. , Wilson R. W.
Published: June 2019

In order to study the excitation conditions in the Orion-A region, we applied an LVG code to 12CO, 13CO and C18O data obtained with the AT&T Bell Laboratories 7-meter telescope in USA (CO isotopes: J = 1 — 0, CS: J = 2 — 1) and the radiotelescope of the "Groupe d'Astrophysique de Grenoble" in France (CO isotopes: J = 2 — 1).
“CO line broadening by saturation effect in molecular clouds”
Authors: Lépine Jacques R.D.
Published: June 2019

A new discussion of the evidences for turbulences in molecular clouds, taking into account line broadenning by saturation at large optical depths, shows that the generally accepted power law dependence of turbulent velocity with cloud size must be revised.
An 8″ resolution CO (J=3−2) map of IC342
Authors: Mauersberger R. , Schulz A. , Baars J.W.M. , Steppe H.
Published: June 2019

IC342 (Distance 4 Mpc) is one of the most suitable sources for extragalactic molecular line studies. Toward its nucleus, a great number of molecular species have been found (see Henkel and Mauersberger, 1990); it is also one of the few galaxies investigated in molecular multi-level studies (Mauersberger and Henkel, 1989). In particular, CO shows strong emission: A 7″ resolution interferometric map of the central parts of this galaxy in the 12CO(1—0) transition by Lo et al. (1984) reveals that the circumnuclear molecular gas is distributed in a bar (size 15″ × 70″) (330 × 1500 pc) extending from the nucleus towards the spiral arms. An interferometric map of the 1—0 line of CO by Ishizuki et al. (1990) shows that the inner part of the bar forms a molecular ring of diameter 110 pc. This inner ring also emits 2 and 6 cm continuum radiation (Turner and Ho, 1983). The kinetic temperature of the denser molecular gas is > 50 K (Martin and Ho, 1986). The H2 density of the gas component seen in CO (Eckart et al., 1990) and CS (Mauersberger and Henkel, 1989) is ∼ 104 cm−3.
Bright-rimmed clouds with IRAS point sources: candidates for star formation by radiation-driven implosion
Authors: Sugitani Koji , Fukui Yasuo , Ogura Katsuo
Published: June 2019

We present preliminary results of a survey of bright-rimmed clouds associated with IRAS point sources.

Bright-rimmed globules associated with old HII regions have long been suspected as a potential site for star formation. Physical conditions of such clouds seem to well match to models of radiation-driven implosion, which have been studied as an effective process for induced star formation (e.g. Klein et al. 1985, Bertoldi 1989). Bright-rimmed globules associated with IRAS point sources are good candidates for the sites of induced star formation. Three well-established cases of radiation-driven implosions in bright-rimmed globules (Ori I-2, IC1396-n, and L1206) were reported (Sugitani et al. 1989). Similar examples were also reported in HH46/47 (Olberg et al. 1989) and in GN21.38.9 (Duvert et al. 1990). However, the samples are still not numerous enough to establish comprehensive understanding of star formation by such implosion process.
Density structure of dense cores in the Cepheus molecular cloud
Authors: Sunada K. , Hasegawa T. , Hayashi M. , Fukui Y. , Sugitani K.
Published: June 2019

We mapped 5 dense cores in the Cepheus molecular cloud in the optically thin C18O (J = 1 — 0) line using the 45-m telescope at Nobeyama and derived density profiles around those cores assuming spherical symmetry. Cloud cores are selected from the 13CO (J = 1 — 0) map obtained through the unbiased survey program with the 4-m telescope at Nagoya university.
Measuring the fractal structure of interstellar clouds
Authors: Vogelaar M.G.R. , Wakker B. P. , Schwarz U. J.
Published: June 2019

To study the structure of interstellar clouds we used the so-called perimeter-area relation to estimate fractal dimensions. We studied the reliability of the method by applying it to artificial fractals and discuss some of the problems and pitfalls. Results for two different cloud types (high-velocity clouds (HVCs) and infrared cirrus) are summarized. We find dimensions 1.2<D<1.55, somewhat higher than found in previous, similar studies.
An extensive study of interstellar matter in the IC 1396 region using several molecular lines and transitions of CO and far-infrared maps from IRAS
Authors: Weikard H. , Sugitani K. , Duvert G. , Miller M.
Published: June 2019

IC 1396 is an H II region in Cepheus excited by the massive 06.5 star HD 206267. The distance is about 750 pc. The region exhibits a number of bright-rimmed molecular clouds in which outflows have been detected (Sugitani et al. 1989, Duvert et al. 1990).
Gravitational virialization of molecular cloud fragments
Authors: Whitworth Anthony
Published: June 2019

We argue that if gravitational interactions play an important role in the amplification and transfer of turbulent energy between sub-clouds of different scales in a GMC, then the Second Law of Thermodynamics requires that the transfer occur from smaller to larger scales, and hence that the seed-energy be injected on relatively small scales.
Turbulent amplification of interstellar magnetic fields
Authors: Whitworth Anthony
Published: June 2019

We show that the radiative cooling properties of the interstellar gas lead naturally to a scaling law for the magnetic field of the form B ∝ n1/2, if the magnetic field is amplified by a vigorous injection of turbulent energy due to expanding HII regions, stellar winds, supernova explosions, stellar jets, etc.
The TopHat Cosmic Microwave Background Anisotropy Experiment
Authors: Silverberg Robert F. ,   The TopHat Collaboration
Published: June 2019

We have developed a balloon-borne experiment to measure the Cosmic Microwave Background Radiation anisotropy on angular scales from ˜50° down to ˜20′. The instrument observes at frequencies between 150 and 690 GHz and will be flown on an Antarctic circumpolar long duration flight. To greatly improve the experiment performance, the front-end of the experiment is mounted on the top of the balloon. With high sensitivity, broad sky coverage, and well-characterized systematic errors, the results of this experiment can be used to strongly constrain cosmological models and probe the early stages of large-scale structure formation in the Universe.
Mapping the Galactic Free-Free Foreground via Interstellar Hα Emission
Authors: Reynolds R. J. , Haffner L. M.
Published: June 2019

Recently completed Hα surveys of large portions of the sky can be used to create maps of the free-free intensity distribution at high Galactic latitude that are independent of the spectral fits to the CMB data. This provides an opportunity to test the accuracy of the spectral fitting procedures and to search for other sources of Galactic forground contamination that could be confused spectrally with the free-free, such as spinning dust grains. The Wisconsin Hα Mapper (WHAM) survey has sampled the sky north of declination −30° at about one degree angular resolution and has revealed that, except for a few isolated regions of enhanced emission, δTff (30 GHz) ≲ 30 μK at Galactic latitudes near 15°, decreasing to δTff(30 GHz) ≲ 4 μK at latitudes above 50°. Also in progress are Hα surveys that sample the sky at higher angular resolution.
Local Distance Indicators
Authors: Feast Michael.
Published: June 2019

A summary is given of the calibration of the Cepheid scale required in the derivation of distances from observations at V and I, as in the HST work on extragalactic Cepheids. There is some evidence that a small metallicity correction may be necessary in deriving distances in this way. The evidence for this comes both from observations of Cepheids of different metallicities and from a comparison of the LMC distance modulus derived from Cepheids and that derived by other methods.
Ω0 Concordance
Authors: Fukugita Masataka.
Published: June 2019

The determinations of the mass density parameter Ω0 are examined with a particular emphasis given to the new cosmic microwave background (CMB) experiments. It is shown that the Ω0 and the Hubble constant H0 from CMB are quite consistent with those from other observations with the aid of the hierarchical structure formation models based on cold dark matter dominance with the cosmological constant that makes the universe flat. The concordance value of Ω0 is 0.25-0.45.
The X-ray Background as a Cosmological Tool
Authors: Barcons X. , Carrera F. J. , Ceballos M. T.
Published: June 2019

We review the use of the X-ray background (XRB) as a cosmological tool with emphasis on three techniques: multipole analysis, autocorrelation functions and excess fluctuations. Although these methods of analysis of XRB fluctuations, and in particular the excess fluctuations method, are quite sensitive to cosmological parameters, the poor knowledge of a possibly redshift dependent bias parameter for the sources that dominate the X-ray background prevents the derivation of firm conclusions at present. Conversely, knowledge of the cosmological parameters could be used together with XRB fluctuations to assess the clustering properties of AGN as the dominant XRB sources.
The Sky Polarisation Observatory (SPOrt) Program
Authors: Carretti E. , Cortiglioni S. , Tucci M. , Cecchini S. , MacCuli C. , Orsini M. , Monari J. , Orfei A. , Poppi S. , Bonometto S. , Boella G. , Gervasi M. , Sironi G. , Zannoni M. , Fabbri R. , Nicastro L. , Tascone R. , Pisani U.
Published: June 2019

The goal of the Sky Polarisation Observatory (SPOrt) Program is the measurement of the sky linearly polarised emission in the 22-90 GHz frequency range from the International Space Station (2003-2004). The instrument configuration together with most relevant ground support activities are presented. In particular, the development of hardware solutions for high sensitive polarimetric measurements has been addressed by the SPOrt team to match the experiment requirements.
Constraints on Cosmological Models from Cosmic Flows
Authors: Hudson Michael J. , Smith Russell J. , Lucey John R. , Schlegel David J. , Davies Roger L.
Published: June 2019

The SMAC cluster sample (Hudson et al. 1999), with a depth of ˜ 12000km s-1, has a bulk velocity of ˜ 600 km s-1, with respect to the Cosmic Microwave Background (CMB) frame. Other surveys (Willick 1999, hereafter LP10k; Lauer & Postman 1994, hereafter ACIF) have also yielded large bulk motions on similarly large scales. Taken at face value, these results appear to be in conflict with bulk flows expected from favoured cosmological models. However, at the same time, other surveys (notably Dale et al. 1999, hereafter SC) have found rather small bulk motions on large scales. We have measured bulk flows from the above mentioned surveys plus SNIa (Riess et al. 1995) in a consistent way. The results are given in Table 1. The measurement errors are due to peculiar velocity errors. Note that these are the errors typically quoted. Based on these errors alone, there appears to be conflict between some of the surveys (e.g. SC vs SMAC).
VLA observations of water maser emission associated with SVS 13
Authors: Rodríguez Luis F. , Anglada Guillem , Torrelles José M. , Eduardo Mendoza-Torres J. , Haschick Aubrey D. , Ho Paul T. P.
Published: June 2019

The young stellar object SVS 13 has been proposed as the powering source of the HH 7-11 objects. Recent observations have revealed that in the radio continuum (3.6-cm) the source is a binary separated by about 0.3 in the east-west direction. We present Very Large Array observations, made in the highest angular resolution A configuration, of H2O maser emission toward this source. Our data show that the H2O spots appear to be segregated in two velocity groups: a group with radial velocity similar to that of the ambient cloud (VLSR ⋍ 8 km s−1) that is associated with the western radio source, and a blueshifted (by ∼20 km s−1) velocity group that is associated with the eastern radio source. We discuss the possible implications of this observation.
Detection of new sources of 4765-MHz OH masing
Authors: Dodson Richard G. , Ellingsen Simon P.
Published: June 2019

We have used the Australia Telescope Compact Array (ATCA) to make a sensitive search for maser emission from the 4765-MHz transition of OH towards a sample of 55 star formation regions. Maser emission with peak flux densities in excess of 100 mJy were detected in 14 sites, with 10 of these being new discoveries. Unlike the ground-state OH transitions the 4765-MHz transition is not predicted to be circularly polarised and none of the masers observed have detectable levels of linear, or circular polarisation. Combining our results with those of previous high resolution observations of other OH transitions we are able to investigate various theoretical models for the pumping of OH masers.
Physical conditions in the NGC 6334 molecular cloud derived from non-LTE NH3(J,K)=(1,1) transitions
Authors: Caproni Anderson , Abraham Zulema , Vilas-Boas José W. S.
Published: June 2019

The high signal-to-noise ratio of the NH3(J,K) = (1,1) spectra from NGC 6334 have allowed at a first time a detailed study of departures from LTE conditions in this molecular cloud. Differences in the line shapes have shown that the surveyed region is composed of at least three overlapped sources in different stages of star formation. Comparison between physical parameters of NGC 6334 derived from LTE and non-LTE conditions are presented and discussed here.
HCN (J=1-0) maser emission in the bright carbon star Y CVn
Authors: Dinh-V-Trung  , Forster James R. , Nguyen-Q-Rieu
Published: June 2019

We present high resolution observations of HCN(J=1-0) line in the bright carbon star Y CVn. With an angular resolution of 0.5 arcsec we are able to resolve the HCN envelope around Y CVn. The HCN(J=1-0) line profile toward the central position exhibits several strong spikes having brightness temperature in excess of 1000 K. This result indicates that the J=1-0 line is masing. We also discuss the pump mechanism of this maser and the implication for the determination of the HCN abundance.
Full-polarization maps of OH main-line masers in the W51 and G351.78-0.54 star-forming regions
Authors: Argon Alice L. , Reid Mark J. , Menten Karl M.
Published: June 2019

Full-polarization spectral-line VLBA observations were made of the ground state, main-line, 2π3/2J = 3/2 OH masers in two Galactic star-forming regions: the “e1”/ “e2” region of W51 and G351.78-0.54. Two especially interesting results are presented. (1) Two of the 27 Zeeman pairs in W51 were found to be associated with unusually strong magnetic fields (≈ 20 mG), more than twice as strong as for any previously reported OH maser. (2) G351.78-0.54 was found to exhibit a high degree of linear polarization (up to 61%), which constrains the three dimensional structure of its magnetic field.
First detection of Zeeman splitting of water masers in circumstellar shells
Authors: Vlemmings Wouter , Diamond Phil , van Langevelde Huib Jan
Published: June 2019

The strength and structure of the magnetic fields in circumstellar envelopes have been measured through polarization observations of OH and SiO masers. Here we present the first results obtained by observing the circular polarization of the H2O masers using VLBI. SiO masers are probes of the high temperature and density regime close to the central star. OH masers are found at much lower densities and temperatures, generally much further out in the circumstellar envelope. The detection of the Zeeman splitting of the (616-523) rotational transition of the H2O maser allows us to determine the magnetic field strength in the intermediate temperature and density regime.
New CCD Survey of Globular Clusters in M31
Authors: Gyoon Lee Myung , Chul Kim Sang , Geisler Doug , Seguel Juan , Sarajedini Ata , Harris William
Published: June 2019

We present a progress report of our wide field CCD survey of globular clusters in M31. We have covered a 3 deg × 3 deg area centered on M31, using the KPNO 0.9m and Washington CMT1 filters. Our survey is much deeper and more sensitive than previous surveys. We have found several hundred new globular cluster candidates in M31 in addition to confirming previously known globular clusters, and also have found a number of interlopers among previous globular cluster catalogs. We have also obtained spectra of about 500 objects among these candidates using HYDRA at the WIYN 3.5m telescope, which are used for classification and measuring the radial velocity of the candidate objects. When completed, a new master catalog of globular clusters in M31 will be made, combining the new globular clusters with the known globular clusters.
Cluster Distances using Delta Scuti Stars; The Open Clusters Praesepe and NGC 7062
Authors: Arentoft Torben , M. Freyhammer Lars
Published: June 2019

Asteroseismology of multiperiodic δ Scuti stars is a powerful tool for providing estimates of distances to the stars being analyzed. Especially δ Scuti stars in clusters offer good possibilities for determining asteroseismic distances, as the stellar models are constrained by assuming common values for chemical composition, age and distance. Recently, we detected a large population of δ Scuti stars in the open cluster NGC 7062. On the basis of these results, we discuss the potential of extending the asteroseismic distance scale for δ Scuti stars to include extra-galactic stellar clusters. Especially high-amplitude δ Scuti stars, pulsating in at least 2 radial modes, offer promising possibilities for doing this.