Astronomical data analysis software and systems

ABSTRACT CLOUDY is a large‐scale spectral synthesis code designed to simulate fully physical conditions within an astronomical plasma and then predict the emitted spectrum. Here we describe version 90 (C90) of the code, paying particular attention to changes in the atomic database and numerical methods that have affected predictions since the last publicly available version, C84. The computational methods and uncertainties are outlined together with the direction future development will take. The code is freely available and is widely used in the analysis and interpretation of emission‐line spectra. Web access to the Fortran source for CLOUDY, its documentation Hazy, and an independent electronic form of the atomic database is also described.

Cloudy: Numerical simulation of plasmas and their spectra

Conferenzrathe, ordentlichem Professor der Astronomie in Copenhagen, Commandeur vom Dannebroge und Dannebrogsmann, Ritter des Königl. Preussischen Rothen Adlerordens zweiter Classe, des Kaiserl. Russischen St . Annenund Stanislausordens zweiter Classe, des Königl. Schwed. Nordsternordens und der Ehrenlegion, Mitgliede der Königl. Gesellschaften derWissenschaften in Copenhagen, London, Edinburgh, Stockholm, Göttingen und Upsala, der Königl. astron. Gesellschaft in London, der americanischen Gesellschaft der Wissenschaften in Philadelphia, der physiographischen Gesellschaft in Lund, und der naturforschenden Gesellschaft in Danzig, Ehren mitgliede der Königl. Gesellschaft der Wissenschaften in Dublin, de r meteorolog. Gesellschaft in London, der Society of useful arts in Edinburgh, der mathematischen Gesellschaft in Hamburg und der naturforschenden Gesellschaft in Rostock, Correspondenten des Französischen Instituts, der Kaiserl. Academie der Wissenschaften in St. Petersburg, der Königl. Gesellschaften der Wissen schaften in Berlin, Brüssel, Neapel, Padua, Palermo und Turin.

The Astronomische Nachrichten

The precise analysis of properties of planetary nebulae is strongly dependent on good models for the stellar ionizing spectrum. Observations in the UV - X-ray wavelength range as well as NLTE model atmosphere calculations of spectra of their exciting stars have shown that neither blackbody fluxes nor "standard" NLTE atmosphere models which are composed out of hydrogen and helium only are good approximations. Strong differences between synthetic spectra from these compared to observed spectra at energies higher than 54 eV (He II ground state) can be ascribed to the neglect of metal-line blanketing. 
Realistic modeling of the emergent fluxes of hot stars in the UV - X-ray wavelength range requires metal-line blanketed NLTE model atmospheres which include all elements from hydrogen up to the iron-group. For this purpose, we present a grid (solar and halo abundance ratios) of metal-line blanketed NLTE model atmosphere fluxes which covers the parameter range of central stars of planetary nebulae.

/pdf/a-grid-of-synthetic-ionizing-spectra-for-very-hot-compact-5g29u7jptm.pdf

A grid of synthetic ionizing spectra for very hot compact stars from NLTE model atmospheres

Planetary nebulae represent a potential late stage of stellar evolution, however the central stars (CSPNe) are relatively faint and therefore pertinent information is merely available for <20% of the Galactic sample. Consequently, the literature was surveyed to construct a new catalogue of 620 CSPNe featuring important spectral classifications and information. The catalogue supersedes the existing iteration by 25%, and includes physical parameters such as luminosity, surface gravity, temperature, magnitude estimates, and references for published spectra. The marked statistical improvement enabled the following pertinent conclusions to be determined: the H-rich/H-poor ratio is 2:1, there is a deficiency of CSPNe with types [WC 5-6], and nearly 80% of binary central stars belong to the H-rich group. The last finding suggests that evolutionary scenarios leading to the formation of binary central stars interfere with the conditions required for the formation of H-poor CSPN. Approximately 50% of the sample with derived values of log L, log Teff, and log g, exhibit masses and ages consistent with single stellar evolutionary models. The implication is that single stars are indeed able to form planetary nebulae. Moreover, it is shown that H-poor CSPNe are formed by higher mass progenitors. The catalogue is available through the Vizier database.

/pdf/catalogue-of-central-stars-of-planetary-nebulae-expanded-4he7lke12m.pdf

Catalogue of central stars of planetary nebulae: Expanded edition

Many round or nearly roundish Planetary Nebulae (PNe) show multiple shells and halo structures during their evolutionary stage near the maximum temperature of their central star. Controversial debate is currently ongoing if these structures are recombination halos, as suggested by hydrodynamic modelling efforts, or ionized material. Recently we discovered a halo with even somewhat unusual structures around the sparsely studied PN IC~5148 and present for the first time spectroscopy going out to the halo of such a PN.} resolution spectroscopy is used to derive dust chemistry and mineralogy. We investigate the spatial distribution of material and its ionization state from the center of the nebula up to the very outskirts of the halo. We obtained long-slit low resolution spectroscopy (FORS2@VLT) of the nebula in two position angles, which we used to investigate the nebular structure and its halo in the optical range from 450 to 880\,nm. In addition we used medium resolution spectra taken with X-SHOOTER@VLT ranging from 320 nm to 2.4 mu to derive atmospheric parameters for the central star. We obtained the distance and position in the Galaxy from various methods combined with GAIA DR2 data. We also applied Cloudy models to the nebula in order to derive physical parameters of the various regions. We obtained spatially resolved structures and detailed descriptions of the outrunning shock front and a set of unusual halo structures denoted to further shock. The halo structures appears clearly as hot ionized material. Furthermore we derived a reliable photometric value for the central star at a GAIA distance of D=1.3kpc. Considering the large distance $z=1.0$\,kpc from the galactic plane together to its non-circular motion in the galaxy and, a metallicity only slightly below that of typical disk PNe, most likely IC 5148 originates from a thick disk population star.

/pdf/the-planetary-nebula-ic-5148-and-its-ionized-halo-5gl8ltchy2.pdf

The planetary nebula IC 5148 and its ionized halo

During the start of a survey program using FORS2 long slit spectroscopy on planetary nebulae (PN) and their haloes, we serendipitously discovered six background emission line galaxies (ELG) with redshifts of z = 0.2057, 0.3137, 0.37281, 0.4939, 0.7424 and 0.8668. Thus they clearly do not belong to a common cluster structure. We derived the major physical properties of the targets. Since the used long slit covers a sky area of only 570 arcsec^2, we discuss further potential of serendipitous discoveries in archival data, beside the deep systematic work of the ongoing and upcoming big surveys. We conclude that archival data provide a decent potential for extending the overall data on ELGs without any selection bias.

Emission line galaxies behind the planetary nebula IC 5148: Potential for a serendipity survey with archival data

The investigation of gaseous nebulae, emitting in forbidden lines, is often based extensively on diagnostic diagrams. The special physics of these lines often allows for disentangling with a few line ratios normally coupled thermodynamic parameters like electron temperature, density and properties of the photo-ionizing radiation field. Diagnostic diagrams are usually used for the investigation of planetary nebulae as a total. We investigated the extension of such integrated properties towards spatially resolved 2D diagnostics, using Hubble Space Telescope/Wide Field Planetary Camera 2 (HST/WFPC2) narrow band images. For this purpose, we also derived a method to isolate pure Hα emission from the [N ii] contamination as normally suffering in the F656N HST/WFPC2 filter.

Analysis of Multiple Shell Planetary Nebulae Based on HST/WFPC2 Extended 2D Diagnostic Diagrams

Context . Planetary nebula distance scales often suffer from model-dependent solutions. Model-independent trigonometric parallaxes have been rare. Space-based trigonometric parallaxes are now available for a larger sample using the second Data Release of Gaia .Aims . We aim to derive a high-quality approach for selection criteria of trigonometric parallaxes for planetary nebulae and discuss possible caveats and restrictions in the use of this Data Release.Methods . A few hundred sources from previous distance scale surveys were manually cross-identified with data from the second Gaia Data Release (DR2) because coordinate-based matching does not work reliably. The data were compared with the results of previous distance scales and to the results of a recent similar study that used the first Data Release Gaia DR1.Results . While the few available previous ground-based trigonometric parallaxes as well as those obtained with the Hubble Space Telescope perfectly match the new data sets, older statistical distance scales, reaching larger distances, do show small systematic differences. When we restrict the comparison to the central stars for which the photometric colors of Gaia show a negligible contamination by the surrounding nebula, the difference is negligible for statistical distances based on radio flux, while those derived from Hα surface brightness still show minor differences. The DR2 study significantly improves the previous recalibration of the statistical distance scales using DR1/TGAS.

/pdf/planetary-nebula-distances-in-gaia-dr2-2jhlapy01r.pdf

Planetary nebula distances in Gaia DR2

We performed a detailed photometric analysis and photoionisation modelling on three high excitation multiple shell planetary nebulae: NGC 3242, NGC 6826 and NGC 7662. Archival HST/WFPC2 narrow band filter images were used to investigate shocked regions by two independent methods: using low excitation ions (via H alpha/[N II] vs H alpha/[S II] extended diagnostic diagrams) and by means of high excitation species looking for regions of enhanced [O III]/H alpha line ratios. Shocked region analysis via low excitation ions shows that major deviations from the general inside to outside ionisation trend correspond only to regions where FLIERs or LISs are located. The reduction on the SNR at the outskirts of the [O III]/H alpha ratio maps, made us unable to unambiguously identified for an enhancement on the [O III]/H alpha line ratio as an indicator for shocks. For non-shocked regions we performed a photoionisation modelling using Cloudy. Fittings to the [O III] and H alpha observed radial profiles lead us to constrain on the free parameters of the density laws and filling factors together to temperatures and luminosities for the CSPNe. Best fit models show a very well representation of the [O III] and H alpha emission. Discrepancies in the model fittings to the [N II] and [S II] profiles at NGC 6826 and NGC 3242, can be attributed in the former case, due to a contamination by the light of the CSPN and, in the latter case, either due to gas inhomogeneities within the clumps or to a leaking of UV radiation.

HST/WFPC2 imaging analysis and cloudy modelling of the multiple-shell planetary nebulae NGC 3242, NGC 6826, and NGC 7662

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

D. Barria

Author Tools

Chat about Author