Alternative diagnostic diagrams and the `forgotten` population of weak line galaxies in the SDSS

A numerous population of weak line galaxies (WLGs) is often left out of statistical studies on emission-line galaxies (ELGs) due to the absence of an adequate classification scheme, since classical diagnostic diagrams, such as [O iii]/H beta versus [N ii]/H alpha (the BPT diagram), require the measurement of at least four emission lines. This paper aims to remedy this situation by transposing the usual divisory lines between star-forming (SF) galaxies and active galactic nuclei (AGN) hosts and between Seyferts and LINERs to diagrams that are more economical in terms of line quality requirements. By doing this, we rescue from the classification limbo a substantial number of sources and modify the global census of ELGs. More specifically, (1) we use the Sloan Digital Sky Survey Data Release 7 to constitute a suitable sample of 280 000 ELGs, one-third of which are WLGs. (2) Galaxies with strong emission lines are classified using the widely applied criteria of Kewley et al., Kauffmann et al. and Stasinska et al. to distinguish SF galaxies and AGN hosts and Kewley et al. to distinguish Seyferts from LINERs. (3) We transpose these classification schemes to alternative diagrams keeping [N ii]/H alpha as a horizontal axis, but replacing H beta by a stronger line (H alpha or [O ii]), or substituting the ionization-level sensitive [O iii]/H beta ratio with the equivalent width of H alpha (W(H alpha)). Optimized equations for the transposed divisory lines are provided. (4) We show that nothing significant is lost in the translation, but that the new diagrams allow one to classify up to 50 per cent more ELGs. (5) Introducing WLGs in the census of galaxies in the local Universe increases the proportion of metal-rich SF galaxies and especially LINERs. In the course of this analysis, we were led to make the following points. (i) The Kewley et al. BPT line for galaxy classification is generally ill-used. (ii) Replacing [O iii]/H beta by W(H alpha) in the classification introduces a change in the philosophy of the distinction between LINERs and Seyferts, but not in its results. Because the W(H alpha) versus [N ii]/H alpha diagram can be applied to the largest sample of ELGs without loss of discriminating power between Seyferts and LINERs, we recommend its use in further studies. (iii) The dichotomy between Seyferts and LINERs is washed out by WLGs in the BPT plane, but it subsists in other diagnostic diagrams. This suggests that the right wing in the BPT diagram is indeed populated by at least two classes, tentatively identified with bona fide AGN and `retired` galaxies that have stopped forming stars and are ionized by their old stellar populations.

Chemically tagging the Hyades stream: does it partly originate from the Hyades cluster?

The Hyades stream has long been thought to be a dispersed vestige of the Hyades cluster. However, recent analyses of the parallax distribution, of the mass function, and of the action-space distribution of stream stars have shown it to be rather composed of orbits trapped at a resonance of a density disturbance. This resonant scenario should leave a clearly different signature in the element abundances of stream stars than the dispersed cluster scenario, since the Hyades cluster is chemically homogeneous. Here, we study the metallicity as well as the element abundances of Li, Na, Mg, Fe, Zr, Ba, La, Ce, Nd and Eu for a random sample of stars belonging to the Hyades stream, and compare them with those of stars from the Hyades cluster. From this analysis: (i) we independently confirm that the Hyades stream cannot be solely composed of stars originating in the Hyades cluster; (ii) we show that some stars (namely 2/21) from the Hyades stream nevertheless have abundances compatible with an origin in the cluster; (iii) we emphasize that the use of Li as a chemical tag of the cluster origin of main-sequence stars is very efficient in the range 5500 K <= T(eff) <= 6200 K, since the Li sequence in the Hyades cluster is very tight, while at the same time spanning a large abundance range; (iv) we show that, while this evaporated population has a metallicity excess of similar to 0.2 dex with respect to the local thin-disc population, identical to that of the Hyades cluster, the remainder of the Hyades stream population has still a metallicity excess of similar to 0.06-0.15 dex, consistent with an origin in the inner Galaxy and (v) we show that the Hyades stream can be interpreted as an inner 4:1 resonance of the spiral pattern: this then also reproduces an orbital family compatible with the Sirius stream, and places the origin of the Hyades stream up to 1 kpc inwards from the solar radius, which might explain the observed metallicity excess of the stream population.

Analysis of total visual and CCD V-broadband observations of Comet C/1995 O1 (Hale-Bopp): 1995-2001

We developed a general method for determination of water production rates from groundbased visual observations and applied it to Comet Hale-Bopp. Our main objective is to extend the method to include total visual magnitude observations obtained with CCD detector and V filter in the analysis of total visual magnitudes. We compare the CCD V-broadband careful observations of Liller [Liller, W. Pre-perihelion CCD photometry of Comet 1995 01 (Hale-Bopp). Planet. Space Sci. 45, 1505-1513, 1997; Liller, W. CCD photometry of Comet C/1995 O1 (Hale-Bopp): 1995-2000. Int. Comet Quart. 23(3), 93-97, 2001] with the total visual magnitude observations from experienced international observers found in the International Comet Quarterly (ICQ) archive. A data set of similar to 400 CCD observations covering about the same 6 years time span of the similar to 12,000 ICQ selected total visual magnitude observations were used in the analysis. A least-square method applied to the water production rates, yields power laws as a function of the heliocentric distances for the pre- and post-perihelion phases. The average dimension of the nucleus as well as its effective active area is determined and compared with values published in the literature. (C) 2009 COSPAR. Published by Elsevier Ltd. All rights reserved.

DETECTABILITY AND ERROR ESTIMATION IN ORBITAL FITS OF RESONANT EXTRASOLAR PLANETS

We estimate the conditions for detectability of two planets in a 2/1 mean-motion resonance from radial velocity data, as a function of their masses, number of observations and the signal-to-noise ratio. Even for a data set of the order of 100 observations and standard deviations of the order of a few meters per second, we find that Jovian-size resonant planets are difficult to detect if the masses of the planets differ by a factor larger than similar to 4. This is consistent with the present population of real exosystems in the 2/1 commensurability, most of which have resonant pairs with similar minimum masses, and could indicate that many other resonant systems exist, but are currently beyond the detectability limit. Furthermore, we analyze the error distribution in masses and orbital elements of orbital fits from synthetic data sets for resonant planets in the 2/1 commensurability. For various mass ratios and number of data points we find that the eccentricity of the outer planet is systematically overestimated, although the inner planet`s eccentricity suffers a much smaller effect. If the initial conditions correspond to small-amplitude oscillations around stable apsidal corotation resonances, the amplitudes estimated from the orbital fits are biased toward larger amplitudes, in accordance to results found in real resonant extrasolar systems.

Short-term effects of gamma ray bursts on Earth

The aim of the present work is to study the potential short-term atmospheric and biospheric influence of Gamma Ray Bursts on the Earth. We focus in the ultraviolet flash at planet`s surface, which occurs as a result of the retransmission of the gamma radiation through the atmosphere. This would be the only important short-term effect on life. We mostly consider Archean and Proterozoic eons, and for completeness we also comment on the Phanerozoic. Therefore, in our study we consider atmospheres with oxygen levels ranging from 10(-5) to 1 of the present atmospheric level, representing different moments in the oxygen rise history. Ecological consequences and some strategies to estimate their importance are outlined.

A Time-Series Analysis of the H alpha Emission Line in V3885 Sagitarii

Flickering is a phenomenon related to mass accretion observed among many classes of astrophysical objects. In this paper we present a study of flickering emission lines and the continuum of the cataclysmic variable V3885 Sgr. The flickering behavior was first analyzed through statistical analysis and the power spectra of lightcurves. Autocorrelation techniques were then employed to estimate the flickering timescale of flares. A cross-correlation study between the line and its underlying continuum variability is presented. The cross-correlation between the photometric and spectroscopic data is also discussed. Periodograms, calculated using emission-line data, show a behavior that is similar to those obtained from photometric datasets found in the literature, with a plateau at lower frequencies and a power-law at higher frequencies. The power-law index is consistent with stochastic events. The cross-correlation study indicates the presence of a correlation between the variability on Ha and its underlying continuum. Flickering timescales derived from the photometric data were estimated to be 25 min for two lightcurves and 10 min for one of them. The average timescales of the line flickering is 40 min, while for its underlying continuum it drops to 20 min.

Multi-Conjugate Adaptive Optics VLT imaging of the distant old open cluster FSR 1415

We employ the recently installed near-infrared Multi-Conjugate Adaptive Optics demonstrator (MAD) to determine the basic properties of a newly identified, old and distant, Galactic open cluster (FSR 1415). The MAD facility remarkably approaches the diffraction limit, reaching a resolution of 0.07 arcsec (in K), that is also uniform in a field of similar to 1.8 arcmin in diameter. The MAD facility provides photometry that is 50 per cent complete at K similar to 19. This corresponds to about 2.5 mag below the cluster main-sequence turn-off. This high-quality data set allows us to derive an accurate heliocentric distance of 8.6 kpc, a metallicity close to solar and an age of similar to 2.5 Gyr. On the other hand, the deepness of the data allows us to reconstruct (completeness-corrected) mass functions (MFs) indicating a relatively massive cluster, with a flat core MF. The Very Large Telescope/MAD capabilities will therefore provide fundamental data for identifying/analysing other faint and distant open clusters in the Galaxy III and IV quadrants.

A carbon isotope challenge to the snowball Earth

The snowball Earth hypothesis postulates that the planet was entirely covered by ice for millions of years in the Neoproterozoic era, in a self-enhanced glaciation caused by the high albedo of the ice-covered planet. In a hard-snowball picture, the subsequent rapid unfreezing resulted from an ultra-greenhouse event attributed to the buildup of volcanic carbon dioxide (CO(2)) during glaciation(1). High partial pressures of atmospheric CO(2) (p(CO2); from 20,000 to 90,000 p. p. m. v.) in the aftermath of the Marinoan glaciation (similar to 635 Myr ago) have been inferred from both boron and triple oxygen isotopes(2,3). These p(CO2) values are 50 to 225 times higher than present-day levels. Here, we re-evaluate these estimates using paired carbon isotopic data for carbonate layers that cap Neoproterozoic glacial deposits and are considered to record post-glacial sea level rise(1). The new data reported here for Brazilian cap carbonates, together with previous ones for time-equivalent units(4-8), provide p(CO2) estimates lower than 3,200 p. p. m. v.-and possibly as low as the current value of similar to 400 p. p. m. v. Our new constraint, and our reinterpretation of the boron and triple oxygen isotope data, provide a completely different picture of the late Neoproterozoic environment, with low atmospheric concentrations of carbon dioxide and oxygen that are inconsistent with a hard-snowball Earth.

Global properties of `ordinary` early-type galaxies: photometry and spectroscopy of stars and globular clusters in NGC 4494

We present a comprehensive analysis of the spatial, kinematic and chemical properties of stars and globular clusters (GCs) in the `ordinary` elliptical galaxy NGC 4494 using data from the Keck and Subaru telescopes. We derive galaxy surface brightness and colour profiles out to large galactocentric radii. We compare the latter to metallicities derived using the near-infrared Calcium Triplet. We obtain stellar kinematics out to similar to 3.5 effective radii. The latter appear flattened or elongated beyond similar to 1.8 effective radii in contrast to the relatively round photometric isophotes. In fact, NGC 4494 may be a flattened galaxy, possibly even an S0, seen at an inclination of similar to 45 degrees. We publish a catalogue of 431 GC candidates brighter than i(0) = 24 based on the photometry, of which 109 are confirmed spectroscopically and 54 have measured spectroscopic metallicities. We also report the discovery of three spectroscopically confirmed ultra-compact dwarfs around NGC 4494 with measured metallicities of -0.4 less than or similar to [Fe/H] less than or similar to -0.3. Based on their properties, we conclude that they are simply bright GCs. The metal-poor GCs are found to be rotating with similar amplitude as the galaxy stars, while the metal-rich GCs show marginal rotation. We supplement our analysis with available literature data and results. Using model predictions of galaxy formation, and a suite of merger simulations, we find that many of the observational properties of NGC 4494 may be explained by formation in a relatively recent gas-rich major merger. Complete studies of individual galaxies incorporating a range of observational avenues and methods such as the one presented here will be an invaluable tool for constraining the fine details of galaxy formation models, especially at large galactocentric radii.

The seaweed flora of Admiralty Bay, King George Island, Antarctic

Admiralty Bay is located on the western side of King George Island. Although several research teams of different nationalities have carried out surveys in the region for decades, there are only two publications dealing with the seaweed flora of the bay. Here, we report on a taxonomic survey of the seaweeds we collected during the 25th Brazilian Antarctic Expedition (December 2006/November 2007). We discovered 42 species (21 Rhodophyta, 14 Phaeophyceae, and 7 Chlorophyta), corresponding to an increase of about 31% in the seaweed biodiversity hitherto known for the region. Considering that the Antarctic Peninsula, adjacent to King George Island seems to be one of the most rapidly warming spots on the planet, this kind of survey may provide a valuable tool for detecting eventual changes in seaweed biodiversity.

Examining Visitor Attitudes and Motivations at a Space Science Centre

The H.R. MacMillan Space Centre is a multi-faceted organization whose mission is to educate, inspire and evoke a sense of wonder about the universe, our planet and space exploration. As a popular, Vancouver science centre, it faces the same range of challenges and issues as other major attractions: how does the Space Centre maintain a healthy public attendance in an increasingly competitive market where visitors continue to be presented with an increasingly rich range of choices for their leisure spending and entertainment dollars?This front-end study investigated visitor attitudes, thoughts and preconceptions on the topic of space and astronomy. It also examined visitors’ motivations for coming to a space science centre. Useful insights were obtained which will be applied to improve future programme content and exhibit development.

Öppna arenor och slutna rum : några kommunikationskonsulter i Dalarna ser på opinionsbildning

Syftet med denna uppsats är att ta reda på hur lokala kommunikationskonsulter i Falun/Borlänge-regionen ser på opinionsbildning via professionella konsulter. De centrala begrepp som avhandlas är PR, opinionsbildning och lobbying.Den teoretiska ram som omger undersökningen består av de teoribyggen som skapats av Jürgen Habermas, James E. Grunig och Larsåke Larsson. Habermas ställer sig tveksam till den demokratiska nyttan av professionell opinionsbildning, Grunig är mer positiv och Larsson ser både för- och nackdelar med PR-verksamheten. Larssons undersökning av opinionskonsulter från 2005 refereras också.Undersökningen bygger på intervjuer med ett antal kommunikationskonsulter verksamma i Falun och Borlänge. Den lokala marknaden för opinionsbildande uppdrag diskuteras, men också huruvida politiska uppdrag förser byråerna med politisk färg. Huruvida medarbetarnas engagemang är viktigt och hur hög statusen på opinionsbildande uppdrag är ventileras, samt vilka arbetsmetoder som används. Intervjuerna behandlar också förekomsten av lobbying på lokal nivå. Till slut redogör de intervjuade för sin syn på hur opinionsbildning, PR och lobbying via konsulter påverkar demokratin.Under slutsatser diskuteras resultatet i relation till den teoretiska ramen. Att PR- och reklambranscherna alltmer växer samman och att opinionsbildning är ett vanligt inslag i många projekt är ett faktum som också skymtat fram i den teoretiska ramen. Men reklam- och PR-metoder integreras också i politiken, på gott och ont. Följaktligen växer den gråzon som finns mellan de olika typerna av kommunikation och mellan opinionsbildande och icke-opinionsbildande uppdrag. Det försvårar gränsdragning och tydlighet, men skapar nya kreativa möjligheter.Att den ökade användningen av kommunikationskonsulter kanske kan bidra till en orättvis fördel för resursstarka organisationer diskuteras. Ny teknik, t.ex. Internet, kan dock eventuellt vara den motvikt som gör det möjligt även för resurssvaga grupper att höras i det offentliga samtalet. Kommunikation som maktfaktor tas även upp utifrån termer som lobbying och medias dagordningsfunktion.Några aspekter av den outnyttjade potential som PR har ventileras också. PR som metod är en outnyttjad resurs på det lokala planet, något som kan bero både på okunskap hos de lokala kunderna och ett traditionellt arbetssätt hos byråerna. Utifrån intervjusvaren framkommer att både byråerna, deras kunder och media på landsorten skulle gynnas av ett större samarbete.Resultaten av intervjuerna stöder mycket i den teoretiska ramen, medan somligt förkastas. Som sammanfattning kan sägas att opinionsbildning via konsulter kan användas för både gott och ont. Vilket som blir resultatet handlar som oftast om etik, ansvar, öppenhet och professionalitet.ABSTRACTThe primary target for this report is to find out how communication consultants in the region of Falun and Borlänge views the practice of establishing public opinions by using professional public relations consultants. The concepts in focus are PR, the moulding of public opinion and lobbying.The theoretical framework surrounding this report is the writings by Jürgen Habermas, James E. Grunig and Larsåke Larsson. Habermas has doubts as to the democratic use of professional consultants working with public opinions, Grunig has a somewhat more positive approach and Larsson sees both advantages and disadvantages in a democratic sense with the PR industry. Larssons research concerning consultants working with the moulding of public opinions from 2005 is also reviewed. The research is carried out by interviewing some communication consultants working in the Falun /Borlänge- area. The local market for commissions concerning public opinions is discussed, but also if and how political commissions are forcing a political stamp upon the firms engaging in such commissions. The importance of personal commitment in the consultants and the level of prominence commissions concerning public opinion has in the business is discussed, but also which methods is used and preferred. The interviews also deal with the practice of lobbying in the local arena. Finally the participants state their views on how the moulding of public opinion, PR and lobbying effects the democracy. Conclusively, the result is put in relation to the theories earlier mentioned. The public relations market is merging with the advertising business, that is a fact, and establishing public opinion is a common element in a lot of projects. But methods used for advertising and PR are also integrated in the political sphere, for good and bad. That has made the distinction between different kinds of communication harder, thereby enhancing the difficulties of establishing boundaries and achieving clarity. Yet at the same time it facilitates new creative opportunities.The growing use of communication consultants may contribute to unfair advantages for organisations with large economic resources. New technical development though, such as the Internet for example, may prove to simplify communication for groups with lesser economic power. Communication as an aspect of power is being discussed in terms of lobbying and the agenda setting power of media.Some aspects of the unused potential that lies within PR are also in focus in this report. PR as a method is an unused resource in the local market, which can be due to the local clients lack of knowledge but also to the traditional work carried out by the communication firms. The findings of the interviews show that both communication firms, their clients and the local media would benefit from greater cooperation.The theoretical base in this work is mostly supported by the interviews, though a few of the findings does not agree. The moulding of public opinions by professional consultants can be used for both good and bad. What the result will be is, not surprisingly, a question of ethics, responsibility, openness and professionalism.

Skolk : en undersökning om hur personal på en skola tänker kring ämnet

Skolk innebär olovlig frånvaro från skolan och det finns undersökningar som visar på att skolk är ett uttryck för ungdomens en i hög grad riskfylld livssituation där misslyckandet med skolan ofta leder till missbruk och kriminalitet. Det har visat sig att bland skolkarna finns både kriminalitet, droger, tobak, ungdomskriminalitet och andra problem överrepresenterat jämfört med icke skolkande elever. Det finns olika svar på var skolk beror på enligt vad som framkommer vid undersökningar bland elever, men den vanligaste orsaken är att bland eleverna som skolkade är det vanligt med bristande tillsyn från föräldrarna och missbruk hos föräldrarna, så kallade familjerelaterade faktorer. När det gäller skolrelaterade faktorer till skolk är bristen på uppmuntran att närvara i skolan en faktor som påverkar och andra förklaringar är missnöje med skolpersonal, lektioner och attityder hos personal och andra elever. Syftet med detta examensarbete är att utifrån kvalitativa intervjuer med rektor, lärare och personal inom elevhälsan undersöka hur skolkproblematik hanteras och vilka tankar som finns kring skolk. För att få fram ett relevant underlag har jag som metod valt att göra en kvalitativ studie som står för forskning där datainsamlingen fokuserar på data i form av till exempel kvalitativa intervjuer. Jag har valt att intervjua personal på en skola i Mellansverige, år 6-9, och bland informanterna finns både lärare, rektor och personal ur elevhälsan. Jag har också använt mig av litteratur, rapporter och avhandlingar som berör skolk som jag applicerat på intervjusvaren i analysen. Jag kom fram till att skolpersonalen visar en god vilja att arbeta för att elever inte ska skolka då det finns mycket negativt med ett sådant beteende. Dels är skolk en indikator på att något inte är bra kring eleven, oftast något på det sociala planet, och dels kan det leda till asociala beteenden som kriminalitet. Oro finns också för att en elev som skolkar påverkar andra att göra likadant och dessutom kan elever som skolkar få problem att sköta sitt arbete som vuxen. Dessutom har jag under arbetes gång utvecklat flera idéer kring fortsatt forskning på området.

Tystnaden i ljudfilm : En studie i Jacques Tatis ”Mon Uncle”

Hellström, Staffan. Tystnaden i ljudfilm - En studie i Jacques Tatis ”Mon Uncle”. C-uppsats. Falun: Institutionen för kultur & medier, Högskolan Dalarna. HT-2008Denna uppsats undersöker Jacques Tatis användning av tystnaden i samspel med ljud och hur de komiska situationerna uppkommer genom detta. Dess syfte är att öka kunskapen för ljudläggare hur man kan använda tystnaden i samverkan med ljud för att uppnå önskat resultat. Den har även som syfte att visa hur specifikt Jacques Tati åstadkommer detta. Uppsatsen innehåller en kvalitativ närläsning, analys och personlig tolkning av fyra scener ur Tatis film ”Mon Uncle” från 1958. Undersökningen är genomförd med ett hermeneutiskt synsätt. Tystnaden definieras som något som endast kan förekomma när ljud existerar.Utredningen genomförs med teoretiskt stöd av Bela Balázs teorier om ljud i film samt Robert Bressons anteckningar om filmkonsten. Bressons filmer är väldigt liknande Tatis filmer på det tekniska planet och är därför relevanta för jämförelser.Sammanfattningsvis kan det sägas att Tati ljudmässigt skapar sina komiska situationer genom ett samspel mellan ljud, tystnad och ett repeterande av monotona ljud. I likhet med Bresson är han intresserad att lyfta fram det osedda och göra oss uppmärksamma på tystnaden.

An analysis of Samoan reaction to The Orator (O Le Tulafale)’s Fāgogo defining Samoan identity

The Orator (O Le Tulafale) was promoted as the first Samoan language film shot in Samoa with a Samoan cast and crew. Written and directed by Samoan filmmaker Tusi Tamasese, the film succeeded at several of the movie industry’s prestigious festivals. The Orator (O Le Tulafale) is about an outcast family of a dwarf (Saili), his wife and her teenage daughter. As the main protagonist, Saili battles to overcome his fears to become a chief to save his family and land. The film’s themes are courage, love, honour , as well as hypocrisy, violence, and discrimination. A backlash by Samoans was predicted ; however, the opposite occurred. This raised the following questions: first, what is it about the film causing this reaction? It is a 106 -minute film shot in Samoa about Samoans and the Samoan culture . D espite promotional claims about the film , there have been Samoan -produced films in Samoa . Secondly, to what are Samoans really responding? Is it 1) just to the film because it is about Samoa, or 2) are they responding to themselves , and how they reacted during the act of watching the film? This implies levels of reactions in the act of watching, and examining the dominant level of response is important. To explore this, t he Samoan story telling technique of Fāgogo was used to analyse the film’s narration and narrative techniques. R. Allen’s (1993, 1997) concept of projected illusion was employed to discuss the relationship between Samoans and the film developed during the act of watching. An examination of the term Samoan and a description of the framework of Fa’a Samoa (Samoan culture) were provided. Also included were discussions of memory and its impact on Samoan cultural identity. The analysis indicated that The Orator (O Le Tulafale) acted as a memory prompt through which Samoans recalled memories confirming and defining cultural bonds. These memories constituted the essence of being Samoan. These memories were awakened, and shared as oral histories as fāgogo. The receivers appeared to interpret the shared memories to create their own memories and stories to suit their contexts, according to Facebook postings. An interpretation is that the organic sharing of memories as fā gogo created a global definition of Samoan that Samoans internationally claimed.