DOCSLIB.ORG

Photoelectric Spectrophotometry of Η Carinae

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Photoelectric Spectrophotometry of Η Carinae Proceedings of the NATIONAL ACADEMY OF SCIENCES Volume 55 * Number 4 * April 15, 1966 PHOTOELECTRIC SPECTROPHOTOMETRY OF q CARINAE BY L. H. ALLER UNIVERSITY OF CALIFORNIA (LOS ANGELES) Communiccaed February 7, 1966 Although i7 Carinae has been known as a remarkable variable for many years, the actual complexities of this bizarre object have become appreciated very re- cently. Although some of its present spectroscopic characteristics resemble those exhibited at moderately advanced phases in conventional slow novae,' the object is certainly not a nova. In a large telescope X Carinae appears as an intensely red star like condensation of somewhat more than a second of arc in diameter, surrounded by an elliptical nebulosity of much lower surface brightness about 10 see in diameter. Surround- ing all this is an extended diffuse nebula in which numerous stars are involved in dust and gas. At the present epoch, the spectrum consists of: (a) an underlying continuum whose energy distribution has recently been measured over the visible and infrared by Searle and Rodgers ;2 (b) numerous emission lines of which the strongest are those of hydrogen and ionized iron; the profile of a typical strong line consists of a broad dome-shaped structure (presumably widened by an expansion velocity of the order of 400 km/sec) on which is superposed a relatively narrow emission line; and (c) absorption lines, displaced to the violet, and sometimes of complex structure, which are associated with the emission lines. Although spectroscopic observations have been secured by a number of observers and a very complete discussion has been given by Thackeray,3 quantitative line intensity data were lacking. Accordingly, as soon as the object was available in the morning skies late in 1960, D. J. Faulkner and I undertook measurements with the Michigan photoelectric scanner which has been designed and built by Liller.4 The observing procedure is very similar to that employed in measurements of other stars5 except that we used medium and low scanning speeds. We employed an exit slot giving a resolution of 9 A and an entrance diaphragm as small as seeing and guiding conditions would permit. Observations of standard stars of known energy distribution supplied the necessary information on the combined effects of re- sponse characteristics of the equipment, transmission of the optics, and atmospheric transparency. 671 Downloaded by guest on October 1, 2021 672 ASTRONOMY: L. H. ALLER PROC. N. A. S. Fea~~~~~~~~~~~~~~~~~~aFaI R Fi e[F SLIT~~~~~~~~~~~~~~~~~~~~ DARK CURRENT 4W 4~9 II WAVELENGTH I I FIG. 1.-Tracing of the spectrum of X7 Carinae, October 15-16, 1960. This reproduction of the first observation secured is intended to display the prominence of the ionized iron lines, many of which are forbidden, in the spectrum of q Carinae and to suggest some of the difficulties in locating the background continuum. The latter task was greatly facilitated by high dispersion spectro- grams secured with the coud6 spectrograph. The resolution is about 9 A so that many of the lines are blended. Figure 1 reproduces a trace obtained at medium speed with the 26-in. telescope at Mount Bingar and illustrates the general characteristics of the spectrum. We secured tracings at Bingar on October 15, October 22, November 15 (1960), January 13 and January 14 (1961), and with the 50-in. telescope at Mount Stromlo on Jan- uary 30, 1961. No evidence appeared of any spectral changes during this period. We sought to measure (a) the energy distribution in the continuum, (b) the rela- tive intensities of the emission lines, and (c) the absolute fluxes in terms of ergs cm-2 sec-' reaching the top of the earth's atmosphere by calibrating one or more of the stronger lines. The continuum may be located as the "envelope" under the emission lines on the tracings. One must also allow for effects of blends and occasional absorption fea- tures. For the spectral region short of X4950, assessment of the data was aided by availability of high-dispersion plates secured with the coud6 spectrograph of the 74- in. telescope. I combined data from the various nights' scans, weighting them inversely according to scanning speeds, and directly in proportion to the light- gathering power of the telescope used. Figure 2 shows the adopted energy distribution in the continuum (compare ref. 2). Notice the discontinuity near the limit of the Balmer series. Some scatter in the points is produced by difficulties in locating the continuum under the emission lines. Downloaded by guest on October 1, 2021 VOL. 55, 1966 ASTRONOMY: L. H. ALLER 673 N ( 0 cm~~~~~~~~~~~~~~~~~~~~~~~~~~~~~( S 0 20 25 1/A FIG. 2.-Measured energy distribution in the continuum of v Carinae. Intensity on a logarithmic scale is plotted against reciprocal wavelength (pull), on basis of observa- tions secured (October 1960-January 1961). No correc- tion for space absorption has been employed. The Balmer jump at 1/X = 2.7 appears to be somewhat smaller than that found by Searle et al.,2 but some of the discrepancy may arise from the great difficulties in making reliable intensity measurements in the ultraviolet and different interpretations of the position of the continuum. Near the ends of the spectral ranges covered, large errors arise from the low sensi- tivity of the 1P21 cell, or effects of atmospheric transparency. Table 1 gives the relative intensities of all emission lines measured, on the scale I(H3) = 1000. For the stronger lines we may expect errors of the order of 10-30 per cent, lines weaker than 20 (or near the ends of the spectral range covered) may easily be in error by a factor of 2, partly because of uncertainties in locating the con- tinuum. Note the great strengths of the Fell and [Fell] lines. No correction for space reddening has been applied. The next step is to establish the zero point of the intensity scale by calibrating the flux received from H3 in units of ergs cm-2 sec-' at the top of the earth's atmosphere. I compared the emission intensities of H#3, Hy, and HS in 7 Carinae with 100-A intervals in the spectral scans of the comparison stars a Crucis, f3 Orionis, and r Puppis, using U, B, V magnitudes measured by Hogg6 and Willstrop's7 calibration of stars of magnitude V = 0 and various B - V color values, in terms of fluxes im- pinging on the top of the earth's atmosphere. These data yielded F(H3) = 0.89 X 10-9 ergs cm-2 sec-' as the flux received at the top of the earth's atmosphere. The measured flux in the stellar continuum at X5560 was 0.81 X 10-1" ergs cm-2 sec-', which corresponds to a visual magnitude of 6.7. We must now correct for the extinction of light in the interstellar medium. We adopt a visual absorption, A, = 1.8 magnitudes,8 and use the data of Whitford9 to correct for the wavelength dependence of space absorption. Then we find log F(Hf) = -8.20. Let us assume that the core has a radius of 2!5 (Searle and Rodgers, private com- munication) and a distance of 1600 parsecs. Most of the radiation comes from the core; the surrounding envelope contributes very little and could not be measured separately with our apparatus. The H,3 flux through the surface then becomes 52 ergs cm-2 sec-'. Downloaded by guest on October 1, 2021 674 ASTRi1ONOMY: L. H. ALLER PROC. N. A. S. TABLE 1 LINE INTENSITIES IN THE SPECTRUM OF 17 CARINAE Mean X Mean X Mean A Mean 5979.0 Sill 72 5197.6 Fell 100 5957.6 4541.60 Fell 11 4114.5 [Fell] 31 Sill 15 5182.0 [Fell] 4101 H5 155 5893 Na466 5184.8 [Fell] 41 4534.08 Fell 12 4068.63 [SII] 38.4 5875. Hel 206166 Fl 4533.02 [Fell] 4032.95 Fell 4 5835.658355 6 [HFee][Fell 43°143: 5164.0 [Fell] 1 4522.6 Fell 4026.2 HeI 18 5164. [FeII 512 4520.2 Fell 91 4002.1 Fell 3 5754.8 [NII] 350 5158.0 [Fell] 4515.3 Fell 3993.1 [NilI] 16 5747.0 [Fell] 5154.1 FeII 23: 4508.3 FeII 64 3970.1 He 5719.5 34: 5146.1 FeIl 16 3969.4 FelI 101 5673.2 [Fell] 20 5132.7 Fell 13 4488.8 [Fell] 82 3867.40 [NF I 1 5657.9 Fell 28 3974.2 Fell 5650.4 [Fell] 34 51116.509 [Fell]Fl 62 482[NI44852 [NiI] 3938.3 Fell 5644.0 [Fell] 15 . [Fell] 4471.5 HeI Call 9 5627.3 [Fell] 28 5072.4 [Fell] 16 4472.9 Fell 65 3933.7 5614 10 5060.3 18.5 4474.91 [Fell] 3914.5 Fell 3.9 5587.5 [Fell] 14 5056. SilI 8 4452.11 [FelI] 127 3913.5Ti 5580.8 [Fell] 5048.2 [Fell] 51 4457.95 [FelI] 3888.6 Hel 5556.3 [Fell] 5043.5 [Fell] 4416.28 [Fell] 19 3889.0 H 5551.3 [Fell] 56 5018.4 Fell 345 4413.71 [Fell] 5 3868.7 [Nell] 40 5005.5 5534.9Fell [Fell] 40: 327[el 96 4973.4 26 3 H 5534.935527.3 [FFellII][Fell] 4950. 7 [Fell[Fell] 4387194387.9 HellHeI 36 3838.33835 Mgl 47 5510.7 Cr1I 14 4947 2 [FeII] 28 43 4 Fell 3824.9 Fell 5 5495.8 [Fell] 37 4372.4 [Fell] 29 3797.9 H 5477.2 [Fell] 32 4923.93 Fell 135 4369.3 Fell 25 4905.3 [Fell] 45 4359.34 [Fell] 264 3764.1 Fell 5433.1 [Fell] 59 4889.6 [Fell] 89 H 352 3769.5 NiII 45 5425.3 Fell 4861 Hg3 1000 4340.30 H 3770.6 H 4814.42 [Fell] 84 4319.6 [Fell] 5412.6 73 5407.6 CrIIlCr11 464 47.[FI]4774.7 [Fell] 43263[Nl]3748.54326.3 [NiII] 3750.2 FellH 313 5376.5 [Fell] 98 47-72.07 [Fell] 4303.2 Fell 5362.1 [Fell], 4728.0 [Fell] 4305.90 [Fell] 50 3734.3 H 25 Fell 30 4731.37 Fell 71 4296.57 Fell 3721.9 H 15 5347.7 [Fell] 24 4713.2 HeI <6.
Load more

Recommended publications
  • WATER CHEMISTRY CONTINUING EDUCATION PROFESSIONAL DEVELOPMENT COURSE 1St Edition
    WATER CHEMISTRY CONTINUING EDUCATION PROFESSIONAL DEVELOPMENT COURSE 1st Edition 2 Water Chemistry 1st Edition 2015 © TLC Printing and Saving Instructions The best thing to do is to download this pdf document to your computer desktop and open it with Adobe Acrobat DC reader. Adobe Acrobat DC reader is a free computer software program and you can find it at Adobe Acrobat’s website. You can complete the course by viewing the course materials on your computer or you can print it out. Once you’ve paid for the course, we’ll give you permission to print this document. Printing Instructions: If you are going to print this document, this document is designed to be printed double-sided or duplexed but can be single-sided. This course booklet does not have the assignment. Please visit our website and download the assignment also. You can obtain a printed version from TLC for an additional $69.95 plus shipping charges. All downloads are electronically tracked and monitored for security purposes. 3 Water Chemistry 1st Edition 2015 © TLC We require the final exam to be proctored. Do not solely depend on TLC’s Approval list for it may be outdated. A second certificate of completion for a second State Agency $25 processing fee. Most of our students prefer to do the assignment in Word and e-mail or fax the assignment back to us. We also teach this course in a conventional hands-on class. Call us and schedule a class today. Responsibility This course contains EPA’s federal rule requirements. Please be aware that each state implements drinking water/wastewater/safety regulations may be more stringent than EPA’s or OSHA’s regulations.
    [Show full text]
  • =« Y * MASS SPECTROMETRIC STUDIES of the SYNTHESIS
    "In presenting the dissertation as a partial fulfillment of the requirements for an advanced degree from the Georgia Institute of Technology, I agree that the Library of the Institution shall make it available for inspection and circulation in accordance with its regulations governing materials of this type. I agree that permission to copy from, or to publish from, this dissertation may be granted by the professor under whose direction it was written, or, in his absence, by the dean of the Graduate Division when such copying or publication is solely for scholarly purposes and does not involve potential financial gain. It is understood that any copying from, or publication of, this dissertation which involves potential financial gain will not be allowed without written permission, "-- -. • i -=« y * MASS SPECTROMETRIC STUDIES OF THE SYNTHESIS, REACTIVITY, AND ENERGETICS OF THE OXYGEN FLUORIDES AT CRYOGENIC TEMPERATURES A THESIS Presented to The Faculty of the Graduate Division by Thomas Joseph Malone In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Chemical Engineering Georgia Institute of Technology February, 1966 MASS SPECTROMETRIC STUDIES OF THE SYNTHESIS, REACTIVITY, AND ENERGETICS OF THE OXYGEN FLUORIDES AT CRYOGENIC TEMPERATURES Approved; / • ' "/v Date approved by Chairma n:\PuJl 3 lUt, 11 ACKNOWLEDGMENTS I am deeply indebted to Dr0 Ho Ao McGee, Jr0 for his encouragement, advice^ and assistance throughout both my graduate and undergraduate studieso Many hours of discussion and willing
    [Show full text]
  • ASTRONOMICAL FILTERS PART 5: Do LP Filters Work?
    ASTRONOMICAL FILTERS PART 5: Do LP Filters Work? In my preceding four articles I have attempted to introduce Next I selected my detectors: the dark adapted (scotopic) everyone to the world of astronomical filters, from simple human eye, and the Sony ICX418AKL colour CCD. This colour filters for planetary work through to fancy light particular CCD was selected since it is the sensor that is in my pollution filters for deep-sky. Based on price alone, I imagine astro-video camera, a Mallincam Xtreme. The CCD has a that the amateur astronomer is most interested in choosing the significantly higher sensitivity in the red and near infrared right light pollution (LP) filter. A hundred dollars (or more) is parts of the spectrum compared to the eye, so I was very eager a lot to invest in a piece of glass that may not actually do to see how the two compared to each other. Once I began my anything. I have performed my own tests on LP filters, both rough calculations I quickly determined that I also had to with an eyepiece and an astro-video camera. My tests have choose a telescope configuration. I chose a configuration been limited to only a couple of different filter types and relevant to my own observing: an 8” f/10 Schmidt-Cassegrain brands. The shear numbers of filters on the market make it with eyepiece/camera effective focal length of 8mm. This pretty much impossible to compare them all side-by-side using gives about 250x power, and a field of view of approximately observations alone.
    [Show full text]
  • CCD Imaging of Planetary Nebulae Or H II Regions
    Observational Astronomy ASTR 310 Fall 2010 Project 2 CCD Imaging of Planetary Nebulae or H II Regions 1. Introduction The aim of this project is to gain experience using the CCD camera by obtaining images of planetary nebulae or H II regions. Planetary nebulae are ionized clouds of gas surrounding very hot stars. The nebula is formed when a star of moderate mass reaches the end of its life as a red giant star, and makes the transition to its final state as a white dwarf. In this process the outer layers of the star are ejected to form the nebula, while the newly exposed core appears as a very hot central star, which emits most of its radiation in the far ultraviolet, thus ionizing and heating the nebula. Most of the radiation emitted by the nebular gas, which has a temperature of ∼10,000 K, is concentrated in the emission lines of a few elements such as oxygen and nitrogen, as well as the most abundant element, hydrogen. An H II region is an interstellar gas cloud with newly formed stars in or near it which are hot enough to ionize some of the gas. While the physical conditions in the gas and the emitted spectrum are similar to planetary nebulae, H II regions are much less regular in appearance and contain much more gas and dust. We will take the images of the nebulae through two narrow-band interference filters which transmit the light of the strongest emission lines in the nebular spectrum. These are the Hα line of hydrogen at 656.3 nm and the line of doubly ionized oxygen (O++ or [O III]) at 500.7 nm.
    [Show full text]
  • Enrichment of the Interstellar Medium by Metal-Rich Droplets and the Abundance Bias in H Ii Regions
    A&A 471, 193–204 (2007) Astronomy DOI: 10.1051/0004-6361:20065675 & c ESO 2007 Astrophysics Enrichment of the interstellar medium by metal-rich droplets and the abundance bias in H ii regions G. Stasinska´ 1, G. Tenorio-Tagle2, M. Rodríguez2, and W. J. Henney3 1 LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, 92190 Meudon, France e-mail: [email protected] 2 Instituto Nacional de Astrofísica Óptica y Electrónica, AP 51, 72000 Puebla, Mexico 3 Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, Apartado Postal 3-72, 58090 Morelia, Mexico Received 23 May 2006 / Accepted 25 May 2007 ABSTRACT We critically examine a scenario for the enrichment of the interstellar medium (ISM) in which supernova ejecta follow a long (108 yr) journey before falling back onto the galactic disk in the form of metal-rich “droplets”, These droplets do not become fully mixed with the interstellar medium until they become photoionized in H ii regions. We investigate the hypothesis that the photoionization of these highly metallic droplets can explain the observed “abundance discrepancy factors” (ADFs), which are found when comparing abundances derived from recombination lines and from collisionally excited lines, both in Galactic and extragalactic H ii regions. We derive bounds of 1013–1015 cm on the droplet sizes inside H ii regions in order that (1) they should not have already been detected by direct imaging of nearby nebulae, and (2) they should not be too swiftly destroyed by diffusion in the ionized gas. From photoionization modelling we find that, if this inhomogeneous enrichment scenario holds, then the recombination lines strongly overestimate the metallicities of the fully mixed H ii regions.
    [Show full text]
  • Synthesis and Study of Photocatalytic and Conducting Nanoparticles And
    ABSTRACT This work entitled “Synthesis and Study of Photocatalytic and Conducting nanoparticles and nanocomposites” presents the synthesis, characterization and study of photo-electrochemical and photocatalytic properties of nanocomposites. This thesis is divided into six (06) chapters and the organization of each chapter is as follows: Chapter 1: Introduction and Review of Literature This chapter gives an introductory description of nanoparticles and semiconductor nanocomposites. It includes a brief account of the principle of photocatalysis by semiconductor nanomaterials and its advancements in the past few decades. The term “nanomaterials” is employed to describe the designing and exploitation of materials with structural features in between those of atoms and giant materials, having at least one of its dimensions in between 0.1nm and 500nm range (1nm = 10- 9m). The various physical properties (viz; dynamic, thermodynamic, mechanical, optical, electronic, magnetic) and chemical properties of nanomaterials can be significantly altered relative to their bulk counterparts. Semiconductor nanoparticles (SC NPs) exhibit different size-dependent properties like electronic band gap energies, solid-solid phase transition temperatures, melting temperatures and pressure responses. To understand photoconductivity, electrical conductivity and related phenomena viz; photocatalysis, it is necessary to understand the energy bands and doping of semiconductors. The reason was expressed by Reithmaier as follows, “the properties of a solid can change dramatically if its dimensions or the dimensions of the constituent phases, become smaller than some critical length associated with these properties” In semiconductors, when an electron gains the extra energy required to get excited into the nearby higher conduction band (CB), it can move freely carrying an electric current.
    [Show full text]
  • Amateur Astronomy Filters
    Amateur Astronomy Filters Eyepiece filters usually screw into the bottom of the eyepiece and come in sizes that fit both 1.25 inch and 2 inch eyepieces. These filters can enhance the contrast of low surface brightness objects like diffuse nebula. They can be used to en- hance the surface features of the planets and Moon, reduce glare of very bright A N T E L O P E V A L L E Y objects, and even enhance the definition of images. There are filters that reduce ASTRONOMY CLUB, INC. the effects of light pollution and those that allow the spectrum to pass through at A 501 (c)(3) Non-Profit only one frequency. Several are summarized below. Organization Solar Filter: This is the filter that will allow you to safely observe the closest star On the web at: to the Earth - the Sun. These filters fit snugly over the front of the telescope and www.avastronomyclub.org are made out of either coated glass, or a Mylar material. Blue Filter: A Wratten #44A, 47B or 80A is used to detect high altitude clouds on Mars, white ovals and spots in the belts of Jupiter, and the zones of the clouds of Saturn, and to reduce the glare of the bright Moon. The 80A is the filter to have if Tel: (661) 724-1623 you only buy one filter. VALLEY ANTELOPE Or (661) 822-4580 Green Filter: A Wratten #58 allows you to see more clearly the edges of the Martian polar caps and enhances the belts and the Great Red Spot in the clouds INC.
    [Show full text]
  • A Second Flavor of Wolf-Rayet Central Stars of Planetary Nebulae
    by Brent Miszalski, Paul Crowther, and Anthony Moffat A Second Flavor of Wolf-Rayet Central Stars of Planetary Nebulae Gemini South optical observations of the planetary nebula IC 4663 reveal the first proven case of a central star with a nitrogen-sequence Wolf- Rayet spectrum. Its existence challenges the conventional view of how certain solar-mass stars become hydrogen-deficient white dwarfs. Population I classical Wolf-Rayet stars represent the short-lived, hydrogen-deficient, pre-su- pernova phase of very massive stars. These hot, high-luminosity bodies possess powerful, fast, dense winds (for recent review see Crowther, 2007). They exhibit unique, broad emission lines generated via Doppler expansion that are readily seen spectroscopically. Wolf-Rayet stars come in two main flavors: nitrogen-rich WN-type stars and carbon-rich WC- type stars. These two classes reflect the products of hydrogen and helium-burning, respec- tively; whereas helium and nitrogen emission lines dominate in WN-types, the WC-types show emission lines mostly of carbon, oxygen, and helium. Very high-mass stars are thought to end their lives as WN or WC stars, although they are exceptionally rare, with only a few hundred cases known in the Milky Way. The Wolf-Rayet Star Phenomenon A subset of low-mass, post-Asymptotic Giant Branch (AGB) stars are also hydrogen-deficient (Werner Herwig, 2006). High temperature examples include He-rich subdwarf OB stars, O(He) stars, and DO white dwarfs. In addition, around 100 hydrogen-deficient central stars of plan- etary nebulae also exhibit a Wolf-Rayet spectroscopic signature. To date, all Wolf-Rayet central stars have been carbon-rich variants, with square brackets added to distinguish [WC]-type central stars from WC stars.
    [Show full text]
  • Oxygen Vacancies and Lithium Vacancies
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Faculty Publications, Department of Physics and Astronomy Research Papers in Physics and Astronomy 2010 Identification of electron and hole traps in lithium tetraborate (Li2B4O7) crystals: Oxygen vacancies and lithium vacancies M. W. Swinney J. W. McClory J. C. Petrosky Shan Yang (??) A. T. Brant See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/physicsfacpub This Article is brought to you for free and open access by the Research Papers in Physics and Astronomy at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications, Department of Physics and Astronomy by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors M. W. Swinney, J. W. McClory, J. C. Petrosky, Shan Yang (??), A. T. Brant, V. T. Adamiv, Ya. V. Burak, P. A. Dowben, and L. E. Halliburton JOURNAL OF APPLIED PHYSICS 107, 113715 ͑2010͒ Identification of electron and hole traps in lithium tetraborate „Li2B4O7… crystals: Oxygen vacancies and lithium vacancies ͒ M. W. Swinney,1 J. W. McClory,1,a J. C. Petrosky,1 Shan Yang (杨山͒,2 A. T. Brant,2 V. T. Adamiv,3 Ya. V. Burak,3 P. A. Dowben,4 and L. E. Halliburton2 1Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio 45433, USA 2Department of Physics, West Virginia University, Morgantown, West Virginia 26506, USA 3Institute of Physical Optics, Dragomanov 23, L’viv 79005, Ukraine 4Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA ͑Received 7 January 2010; accepted 18 March 2010; published online 11 June 2010͒ Electron paramagnetic resonance ͑EPR͒ and electron-nuclear double resonance ͑ENDOR͒ are used to identify and characterize electrons trapped by oxygen vacancies and holes trapped by lithium ͑ ͒ vacancies in lithium tetraborate Li2B4O7 crystals.
    [Show full text]
  • Arxiv:1611.08305V1 [Astro-Ph.GA] 24 Nov 2016
    Draft version November 28, 2016 Typeset using LATEX twocolumn style in AASTeX61 NEBULAR CONTINUUM AND LINE EMISSION IN STELLAR POPULATION SYNTHESIS MODELS Nell Byler,1 Julianne J. Dalcanton,1 Charlie Conroy,2 and Benjamin D. Johnson2 1Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA 2Department of Astronomy, Harvard University, Cambridge, MA, USA (Received November 16, 2016) Submitted to ApJ ABSTRACT Accounting for nebular emission when modeling galaxy spectral energy distributions (SEDs) is important, as both line and continuum emission can contribute significantly to the total observed flux. In this work, we present a new nebular emission model integrated within the Flexible Stellar Population Synthesis code that computes the total line and continuum emission for complex stellar populations using the photoionization code Cloudy. The self-consistent coupling of the nebular emission to the matched ionizing spectrum produces emission line intensities that correctly scale with the stellar population as a function of age and metallicity. This more complete model of galaxy SEDs will improve estimates of global gas properties derived with diagnostic diagrams, star formation rates based on Hα, and stellar masses derived from NIR broadband photometry. Our models agree well with results from other photoionization models and are able to reproduce observed emission from H ii regions and star-forming galaxies. Our models show improved agreement with the observed H ii regions in the Ne iii/O ii plane and show satisfactory agreement with He ii emission from z = 2 galaxies when including rotating stellar models. Models including post-asymptotic giant branch stars are able to reproduce line ratios consistent with low-ionization emission regions (LIERs).
    [Show full text]
  • An Analytic Model for OIII Fine Structure Emission from High Redshift Galaxies
    MNRAS 000,1–16 (2018) Preprint 30 July 2020 Compiled using MNRAS LATEX style file v3.0 An analytic model for [O iii] fine structure emission from high redshift galaxies Shengqi Yang,1? Adam Lidz2 1Center for Cosmology and Particle Physics, Department of physics, New York University, 726 Broadway, New York, NY, 10003, U.S.A. 2Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Recent ALMA measurements have revealed bright [O iii] 88 micron line emission from galax- ies during the Epoch of Reionization (EoR) at redshifts as large as z ∼ 9. We introduce an analytic model to help interpret these and other upcoming [O iii] 88 micron measurements. Our approach sums over the emission from discrete Str¨omgren spheres and considers the total volume of ionized hydrogen in a galaxy of a given star-formation rate. We estimate the relative volume of doubly-ionized oxygen and ionized hydrogen and its dependence on the spectrum of ionizing photons. We then calculate the level populations of OIII ions in different fine-structure states for HII regions of specified parameters. In this simple model, a galaxy’s [O iii] 88 µm lu- minosity is determined by: the typical number density of free electrons in HII regions (ne), the average metallicity of these regions (Z), the rate of hydrogen ionizing photons emitted (QHI), and the shape of the ionizing spectrum. We cross-check our model by comparing it with de- tailed CLOUDY calculations, and find that it works to better than 15% accuracy across a broad range of parameter space.
    [Show full text]
  • Planetary Nebulae
    Spectroscopy of Gaseous Nebulae in Galaxies M. J. Barlow, Dept of Physics & Astronomy, CL O TLINE: (i) Overview of ionized nebulae: HII regions, planetary nebulae and supernova remnants (ii) Determining nebular temperatures, densities and ionic abundances from collisionally excited lines (iii) Measuring element abundances in external galaxies (iv) Probing nebulae with deep spectra: s.process element forbidden lines and recombination lines from C, N, O and Ne. (v) Heavy element abundances from forbidden lines vs. those from optical recombination lines Photoioni)ed Nebulae: two main types HII regions: the brightest examples are the result of the formation of massive stars (> 20 Msun), which then ionize and disperse the natal cloud. The ionizing stars have temperatures of 2 ,000 K " Tstar " 0,000 K. Planetary Nebulae: the final stage in the life of low and intermediate mass stars before they become white dwarfs. The outer envelope is ejected during the red giant ,-. phase and then photoionized by the hot remnant star, with 2 ,000 K " Tstar " 200,000 K. The Orion Nebula (M40) ,n /00 region blister at the front of the 1rion Molecular 2loud Tstar 6 38,000K Large 9uantities of dust can be present in /00 regions 5 b ILL 5 I LL I 5 h b a #$ % D J K L JJ M % N J$ J# OL J LL J a J a JPP J , starburst galaxy with many /00 regions VLT image of NGC 1020. /00 regions show up as white in this image. Spectroscopic studies of heavy element forbidden lines have enabled element abundance gradients to be measured as a function of galactocentric distance for many galaxies.
    [Show full text]