The Determination Of Reddening From Intrinsic VR Colors Of RR Lyrae Stars

New R-band observations of 21 local field RR Lyrae variable stars are used to explore the reliability of minimum light (V-R) colors as a tool for measuring interstellar reddening. For each star, R-band intensity mean magnitudes and light amplitudes are presented. Corresponding V-band light curves from the literature are supplemented with the new photometry, and (V-R) colors at minimum light are determined for a subset of these stars as well as for other stars in the literature. Two different definitions of minimum light color are examined, one which uses a Fourier decomposition to the V and R light curves to find (V-R) at minimum V-band light, (V-R)_{min}^F, and the other which uses the average color between the phase interval 0.5-0.8, (V-R)_{min}^{\phi(0.5-0.8)}. From 31 stars with a wide range of metallicities and pulsation periods, the mean dereddened RR Lyrae color at minimum light is (V-R)_{min,0}^F = 0.28 pm 0.02 mag and (V-R)_{min,0}^{\phi(0.5-0.8)} = 0.27 pm 0.02 mag. As was found by Guldenschuh et al. (2005) using (V-I) colors, any dependence of the star's minimum light color on metallicity or pulsation amplitude is too weak to be formally detected. We find that the intrinsic (V-R) of Galactic bulge RR Lyrae stars are similar to those found by their local counterparts and hence that Bulge RR0 Lyrae stars do not have anomalous colors as compared to the local RR Lyrae stars.Comment: accepted by A

The Variable Stars and Blue Horizontal Branch of the Metal-Rich Globular Cluster NGC 6441

We present time-series VI photometry of the metal-rich ([Fe/H] = -0.53) globular cluster NGC 6441. Our color-magnitude diagram shows that the extended blue horizontal branch seen in Hubble Space Telescope data exists in the outermost reaches of the cluster. The red clump slopes nearly parallel to the reddening vector. A component of this slope is due to differential reddening, but part is intrinsic. The blue horizontal branch stars are more centrally concentrated than the red clump stars. We have discovered about 50 new variable stars near NGC 6441, among them eight or more RR Lyrae stars which are very probably cluster members. Comprehensive period searches over the range 0.2-1.0 days yielded unusually long periods (0.5-0.9 days) for the fundamental pulsators compared with field RR Lyrae of the same metallicity. Three similar long-period RR Lyrae are known in other metal-rich globulars. With over ten examples in hand, it seems that a distinct sub-class of RR Lyrae is emerging. The observed properties of the horizontal branch stars are in reasonable agreement with recent models which invoke deep mixing to enhance the atmospheric helium abundance, while they conflict with models which assume high initial helium abundance. The light curves of the c-type RR Lyrae seem to have unusually long rise times and sharp minima. Reproducing these light curves in stellar pulsation models may provide another means of constraining the physical variables responsible for the anomalous blue horizontal branch extension and sloped red clump observed in NGC 6441.Comment: 30 pages plus 6 EPS and 6 JPEG figures; uses AAS TeX. Accepted by the Astronomical Journal. Minor changes include computing He abundance, modifications to Figs 1 and 8, and expansion on idea that blue HB stars may be produced in binarie

Analysis of RR Lyrae Stars in the Northern Sky Variability Survey

We use data from the Northern Sky Variability Survey (NSVS), obtained from the first generation Robotic Optical Transient Search Experiment (ROTSE-I), to identify and study RR Lyrae variable stars in the solar neighborhood. We initially identified 1197 RRab (RR0) candidate stars brighter than the ROTSE median magnitude V = 14. Periods, amplitudes, and mean V magnitudes are determined for a subset of 1188 RRab stars with well defined light curves. Metallicities are determined for 589 stars by the Fourier parameter method and by the relationship between period, amplitude, and [Fe/H]. We comment upon the difficulties of clearly classifying RRc (RR1) variables in the NSVS dataset. Distances to the RRab stars are calculated using an adopted luminosity-metallicity relation with corrections for interstellar extinction. The 589 RRab stars in our final sample are used to study the properties of the RRab population within 5 kpc of the Sun. The Bailey diagram of period versus amplitude shows that the largest component of this sample belongs to Oosterhoff type I. Metal-rich ([Fe/H] > -1) RRab stars appear to be associated with the Galactic disk. Our metal-rich RRab sample may include a thin disk as well as a thick disk population, although the uncertainties are too large to establish this. There is some evidence among the metal-rich RRab stars for a decline in scale height with increasing [Fe/H], as was found by Layden (1995). The distribution of RRab stars with -1 < [Fe/H] < -1.25 indicates that within this metallicity range the RRab stars are a mixture of stars belonging to halo and disk populations.Comment: 68 pages, 26 figures, 9 tables, accepted to A

The Konkoly Blazhko Survey: Is light-curve modulation a common property of RRab stars?

A systematic survey to establish the true incidence rate of the Blazhko modulation among short-period, fundamental-mode, Galactic field RR Lyrae stars has been accomplished. The Konkoly Blazhko Survey (KBS) was initiated in 2004. Since then more than 750 nights of observation have been devoted to this project. A sample of 30 RRab stars was extensively observed, and light-curve modulation was detected in 14 cases. The 47% occurrence rate of the modulation is much larger than any previous estimate. The significant increase of the detected incidence rate is mostly due to the discovery of small-amplitude modulation. Half of the Blazhko variables in our sample show modulation with so small amplitude that definitely have been missed in the previous surveys. We have found that the modulation can be very unstable in some cases, e.g. RY Com showed regular modulation only during one part of the observations while during two seasons it had stable light curve with abrupt, small changes in the pulsation amplitude. This type of light-curve variability is also hard to detect in other Survey's data. The larger frequency of the light-curve modulation of RRab stars makes it even more important to find the still lacking explanation of the Blazhko phenomenon. The validity of the [Fe/H](P,phi_{31}) relation using the mean light curves of Blazhko variables is checked in our sample. We have found that the formula gives accurate result for small-modulation-amplitude Blazhko stars, and this is also the case for large-modulation-amplitude stars if the light curve has complete phase coverage. However, if the data of large-modulation-amplitude Blazhko stars are not extended enough (e.g. < 500 data points from < 15 nights), the formula may give false result due to the distorted shape of the mean light curve used.Comment: Accepted for publication in MNRAS, 14 pages, 7 Figure

Optimization of mass spectrometry imaging technologies for future application in environmental toxicology studies

La imatge per espectrometria de masses pot revolucionar les ciències òmiques pel fet de caracteritzar canvis moleculars amb context espacial. En aquest estudi, hem optimitzat protocols de lipidòmica espacial per tal d’analitzar embrions de peix zebra, una alternativa als models animals clàssics en estudis de toxicologia ambiental. Així, s’han avaluat una tècnica convencional d’ionització per desorció làser assistida per matriu - imatge per espectrometria de masses (MALDI-MSI, de matrix-assisted laser desorption/ionization - mass spectrometry imaging) i una tècnica desenvolupada recentment anomenada MALDI-2. Els resultats mostren que ambdues tècniques permeten analitzar les seccions de teixit de forma reproduïble amb una alta resolució espacial. La combinació amb l’anàlisi quimiomètrica ha permès observar una clara diferenciació en el contingut lipídic de les diferents zones del cos de l’embrió i es demostra així la utilitat que pot tenir en estudis (eco)toxicològics futurs.Mass spectrometry imaging has the potential to revolutionize omics by characterizing molecular changes with spatial context. In this study, we optimized spatial lipidomics protocols to analyze zebrafish embryos, an alternative to classical animal models in the environmental toxicology field. Specifically, a conventional MALDI-MSI technique and a recently developed technique called MALDI-2 were evaluated. The results show that both techniques allow reproducible tissue section analysis with high spatial resolution. By combining them with chemometric analysis, a clear differentiation has been observed in the lipid content of different regions of the embryo body, demonstrating the utility of these techniques in future (eco)toxicological studies

Citizen science and small libraries: Considerations on the involvement of volunteer re- searchers in the Kreisarchiv and Landeskundliche Bibliothek des Märkischen Kreises

Zielsetzung — Eignen sich kleine Bibliotheken für Citizen Science-Projekte? Ziel des vorliegenden Beitrags war zu prüfen, ob sich partizipative Forschungsprojekte mit der Beteiligung interessierter Bürger*innen auch ohne die technische und personelle Infrastruktur großer Häuser umsetzen lassen oder an welchem Punkt Bibliotheken und Archive mit geringer Zahl von Mitarbeitenden gegebenenfalls an ihre Grenzen stoßen. Forschungsmethoden — Zunächst galt es einen belastbaren Citizen Science-Begriff zu definieren. Wie unterscheiden sich Citizen Science, Citizen Humanities oder Bürgerwissenschaften? Denn viele Projekte sind mit unterschiedlichen Begriffen umschrieben und scheinen zunächst schwer vergleichbar. Um zu prüfen, ob sich in den Beständen der untersuchten Einrichtung grundsätzlich Quellen finden lassen, die eine gemeinsame Bearbeitung ermöglichen, wurden andere Häuser hinsichtlich der Themenstellung ihrer Citizen Science-Projekte ausgewertet. Im Anschluss wurden ausgewählte Best Practices nach einem definierten Katalog hinsichtlich der technischen Umsetzung und des personellen Bedarfs ihrer Projekte ausgewertet und in Bezug zur eigenen Einrichtung gesetzt. Ergebnisse — Die Bestände von Kreisarchiv und Landeskundlicher Bibliothek eignen sich inhaltlich für die gemeinsame Bearbeitung mit der interessierten Öffentlichkeit. Die untersuchten Beispieleinrichtungen zeigen, dass die technische Umsetzung eines Projekts mit überschaubaren Kapazitäten möglich ist. Schlussfolgerungen — Der Erfolg von Citizen Science-Projekten ist nicht abhängig von der Größe der Institution. Ausschlaggebend ist das Engagement der beteiligten Mitarbeitenden und die Arbeiten im Vorfeld des partizipativen Projekts. Wenn die Zielgruppe klar benannt ist, die Quellen vorbereitet und die passenden Tools ausgewählt wurden, ist die Umsetzung eines eigenen Projekts auch mit einem kleinen Team möglich.Objective — Are small libraries suitable for citizen science projects? The aim of this article was to examine whether participatory research projects involving interested citizens can be implemented without the technical and personnel infrastructure of large institutions. Methods — The first task was to define a robust concept of citizen science. What is the difference between citizen science and citizen humanities? In order to check whether sources could be found in the holdings of the examined Archive that would enable a common approach, other institutions were evaluated with regard to the topics of their citizen science projects. Subsequently, selected best practices were evaluated according to a defined catalog with regard to the technical implementation and personnel requirements of their projects and compared to the own institution. Results — The holdings of Kreisarchiv and Landeskundliche Bibliothek are suitable for joint processing with the interested public. The institutions examined show that the technical implementation of a project is possible with small capacities. Conclusions — The success of citizen science projects does not depend on the size of the institution. The decisive factor is the commitment of the employees involved and the work carried out in the run-up to the participatory project. If the target group is clearly defined, the sources have been prepared and the appropriate tools are chosen, it is possible to implement projects even with a small team

Citizen Science in kleinen Bibliotheken. - Eine Machbarkeitsstudie am Beispiel der Landeskundlichen Bibliothek und dem Kreisarchiv des Märkischen Kreises

Eignen sich kleine Bibliotheken für Citizen Science-Projekte? Verschiedene Aspekte verbergen sich hinter dieser kurzen Eingangsfrage: Was sind kleine Bibliotheken? Was bedeutet Citizen Science? Eignen sich Bibliotheken generell für entsprechende Projekte und wenn ja, warum sollten sich kleine Bibliotheken ggfs. nicht oder eben doch besonders eignen? Die vorliegende Masterarbeit möchte diese Fragestellungen anhand des Beispiels von Kreisarchiv und Landeskundlicher Bibliothek des Märkischen Kreises beantworten. Dazu werden zunächst die Begrifflichkeiten definiert. Neben Citizen Science gilt es Vokabeln wie Citizen Humanities oder Crowdsourcing zu diskutieren. Bevor ausgewählte Projekte als Best Practices beleuchtet werden, untersucht die Arbeit, ob sich Bibliotheken und vergleichbare Wissenseinrichtungen als Orte für Citizen Science eignen und ob die Dokumente aus den Magazinen generell als lohnenswert für eine Erforschung durch die interessierte Öffentlichkeit einzustufen sind. Anschließend befragt die vorliegende Ausarbeitung ausgewählte Bestände von Landeskundlicher Bibliothek und Kreisarchiv des Märkischen Kreises auf ihr Potential für etwaige Citizen Science-Projekte und überprüft diese auf ihre Durchführbarkeit mit den vorhandenen Mitteln der Beispieleinrichtung. In einem Fazit werden die Erkenntnisse dieser vergleichenden Betrachtung bewertet und vorgestellt, welches Learning diese Machbarkeitsstudie vergleichbaren kleinen Einrichtungen anbieten kann.Are small libraries suitable for Citizen Science projects? Various aspects are hidden behind this short initial question: What are small libraries? What does Citizen Science mean? Are libraries suitable for Citizen Science projects in general and if so, why should small libraries not be suitable or why should they be particularly suitable? This master's thesis would like to answer these questions using the example of Kreisarchiv und Landeskundliche Bibliothek des Märkischer Kreises. For this purpose, the terms are first defined. In addition to Citizen Science, Citizen Humanities and Crowdsourcing will be discussed. Before selected projects are highlighted as best practices, the thesis examines whether libraries and comparable institutions are suitable places for Citizen Science and whether the holdings from the stacks are "worthwhile" for exploration by the interested public. Subsequently, this paper examines the holdings of the library in Altena for their potential for possible Citizen Science projects and tests their feasibility with the existing resources of the example institution. In a conclusion, the findings of this comparative view are evaluated and it is examined which learning this study can offer for comparable small institutions