Browsing by Author "Pritzl, B. J."
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- ItemA Search for EHB Pulsators in the Globular Cluster NGC 6752(2007) Catelan , Marcio; Prieto, G. E.; Zoccali, M.; Weidner, C.; Stetson, P. B.; Moni Bidin, C.; Altmann, M.; Smith, H. A.; Pritzl, B. J.; Borissova, J.; de Medeiros, J. R.We describe the status of a project whose main goal is to detect variability along the extreme horizontal branch of the globular cluster NGC 6752. Based on Magellan 6.5-m data, preliminary light curves are presented for some candidate variables. By combining our time-series data, we also produce a deep CMD of unprecedented quality for the cluster which reveals a remarkable lack of main sequence binaries, possibly pointing to a low primordial binary fraction....
- ItemErratum: "The Globular Cluster NGC 5286. II. Variable Stars" (2010, AJ, 139, 357)(2010) Zorotovic, M.; Catelan, Márcio; Smith, H. A.; Pritzl, B. J.; Aguirre, P.; Angulo, R. E.; Aravena, M.; Assef, R. J.; Contreras, C.; Cortés, C.; De Martini, G.; Escobar, M. E.; González, D.; Jofré, P.; Lacerna, I.; Navarro, C.; Palma, O.; Prieto, G. E.; Recabarren, E.; Triviño, J.; Vidal, E.The Fourier decomposition program used in our paper contained a small error that affected the calculation of the temperatures as well as the V - I colors inferred for the RRab stars. The temperatures that appear in Table 6 in the published article are slightly overestimated, and the V - I colors underestimated. A corrected version of Table 6 is presented below....
- ItemMetal-Rich Globular Clusters and the Second-Parameter Effect: NGC 6388, NGC 6441(2002) Pritzl, B. J.; Smith, H. A.; Catelan, Márcio; Sweigart, AllenThe second-parameter effect has long challenged our understanding of stellar popullations in global clusters. The RR Lyrae star can be used to examine the effects additional parameters have on the horizontal branch (...)
- ItemRR Lyrae in LMC Globular Clusters(2009) Kuehn, Charles A., III; Smith, H. A.; Taylor, L.; McClellan, R. E.; Catelan, Marcio; Looper, K.; Pritzl, B. J.; De Lee, N.We present preliminary results from a study of five globular clusters located in the Large Magellanic Cloud. The goal of this project is to carry out a large, systematic study of the behavior of RR Lyrae stars in Oosterhoff-intermediate globular clusters. The LMC is an ideal target for a study of this sort as it contains Oosterhoff-intermediate clusters as well as Oo-I/II clusters. We seek to answer three main questions. 1.) Are there double-mode RR Lyrae stars (RRd) in Oo-intermediate clusters and if so how do their properties compare to RRd stars in Oo-I/II clusters? 2.) How do the positions of RR Lyrae stars on the Bailey diagram differ between stars in Oo-intermediate clusters compared to those in Oo-I/II clusters? 3.) How do the Fourier decomposition parameters of RR Lyrae stars change when going from Oo-I/II clusters to Oo-intermediate ones? We present Oosterhoff classifications and sample light curves for some of the clusters in our study and discuss their Fourier parameters and resulting physical properties. We also discuss the implications of our findings on the nature of the Oosterhoff dichotomy and what that implies about Milky Way formation....
- ItemRR Lyrae in LMC Globular Clusters: Insights into the Oosterhoff Phenomenon and Milky Way Formation(2011) Kuehn, Charles A., III; Smith, H. A.; Catelan, Marcio; Taylor, L.; McClellan, R. E.; Looper, K.; DeLee, N.; Pritzl, B. J.We present results from a study of RR Lyrae stars in five globular clusters located in the Large Magellanic Cloud. The goal of this study was to look at the behavior and properties of RR Lyrae stars in Oosterhoff-intermediate globular clusters and compare them to RR Lyrae in Oosterhoff I and II clusters. New BVI photometric observations of these clusters were obtained with the SMARTS consortium telescopes and with the SOAR 4-meter telescope. We present light curves and Fourier properties for the RR Lyrae stars in our study as well as physical properties for these stars derived from their Fourier parameters. We compare these physical properties to those of RR Lyrae in Milky Way halo globular clusters and discuss implications for Milky Way halo formation....
- ItemRR Lyrae in the Large Magellanic Cloud: New Insights Into Oosterhoff Intermediate Globular Clusters(2013) Kuehn, Charles A.; Smith, H. A.; Catelan, Marcio; Pritzl, B. J.; De Lee, N. M.; Borissova, J.Current models suggest that the Milky Way halo was formed through the accretion of objects similar to the present day nearby dwarf galaxies. The ancient nature of RR Lyrae stars make them ideal tracers of stellar populations that can be used to determine how similar the present day dwarf galaxies are to the objects that were accreted to form the Milky Way halo. Globular clusters in the halo can be divided into two groups based on the properties of their RR Lyrae stars, called Oosterhoff groups, with a zone of avoidance between these groups. Nearby dwarf galaxies and their globular clusters fall not only in the Oosterhoff I and II groups, like in the Milky Way, but also in the zone of avoidance between these groups. These Oosterhoff intermediate objects, as the objects that fall in the zone of avoidance are called, present a challenge to the current theories of Milky Way halo formation. We present results of a recent study of globular clusters in the Large Magellanic Cloud which focused on the behavior of individual RR Lyrae stars in Oosterhoff intermediate objects and how this behavior compares to RR Lyrae stars in the other Oosterhoff groups. We discuss how these results demonstrate that Oosterhoff intermediate objects should not be thought of as one homogenous group. We also discuss how these results suggest that the traditional dividing lines between the Oosterhoff groups may need to be revised....
- ItemRR Lyrae Stars: Period-Luminosity Relations and Oosterhoff Groups(2003) Smith, H. A.; Pritzl, B. J.; Catelan, Marcio; Sweigart, A. V.; De Lee, N.; Contreras, R.We use new observations and data from the literature to construct I band period-luminosity relations for RR Lyrae stars in globular clusters. We present synthetic horizontal branches made from theoretical evolutionary models to understand better the effect which horizontal branch morphology has upon the period-luminosity relations in I and several other passbands. We also use the observed relations to address the question of the prevalence of second overtone pulsators among the RR Lyrae stars. We will review an ongoing observational program designed to obtain photometry for variable stars in globular clusters that show the second parameter effect and that cannot be easily placed within the two usual Oosterhoff groups. We thank the National Science Foundation for partial support of this work....
- ItemStellar archaeology in the Milky Way Halo . Variable stars and stellar populations in the new Milky Way satellites discovered by the SDSS(2010) Musella, I.; Clementini, G.; Ripepi, V.; Dall'Ora, M.; Marconi, M.; Greco, C.; Moretti, M. I.; Kinemuchi, K.; Di Fabrizio, L.; Smith, H. A.; Kuehn, C.; Rodgers, C. T.; Beers, T. C.; Catelan, Marcio; Pritzl, B. J.We summarize results from the photometric survey of the recently discovered faint Milky Way satellites: Bootes I, Coma, Ursa Major II, Canes Venatici I, Canes Venatici II and Leo IV. Our team is studying these systems to characterize their stellar populations and structural parameters, as well as their variable star content, with the aim of deriving hints on the formation process of the Galactic halo....
- ItemStellar populations of the newly discovered satellites of the Milky Way .(2008) Dall'Ora, M.; Clementini, G.; Ripepi, V.; Kinemuchi, K.; Greco, C.; Kuehn, C.; Musella, I.; Rodgers, C. T.; Di Fabrizio, L.; Beers, T. C.; Catelan, Marcio; Marconi, M.; Pritzl, B. J.; Smith., H. A.We have carried out an extensive observing campaign on the new dwarf spheroidal galaxies (dSphs) recently discovered by the SDSS, with the aim of characterizing their stellar populations and structural properties, as well as their variable star content. First preliminary results are presented for the Canes Venatici II, the Coma and the Ursa Major II dSphs, based on data collected at a variety of telescopes, and reaching each galaxy's Main Sequence Turn-Off (MSTO)....
- ItemThe Fornax Project(2006) Clementini, G.; Greco, C.; Held, E. V.; Poretti, E.; Catelan, Marcio; Dell'Arciprete, L.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Smith, H. A.; Pritzl, B. J.; Rest, A.; De Lee, N.The Fornax Project aims at mapping the classical instability strip of the Fornax dwarf spheroidal galaxy, from the faint Dwarf Cepheids (V ∼ 24-25 mag) to the bright Anomalous Cepheids (V ∼ 19 mag). To achieve this goal, deep B,V time-series photometry of the galaxy has been obtained with the Wide Field Imagers (WFIs) of the ESO 2.2 m and CTIO 4 m telescopes, and the Clay camera at the Magellan 6.5 m telescope. Preliminary results are presented on the Oosterhoff classification of the RR Lyrae stars identified in a northern portion of Fornax field and in three of its globular clusters....
- ItemThe globular cluster M 69: color-magnitude diagram and variable stars(2010) Escobar, M. E.; Catelan, Marcio; Zoccali, M.; Smith, H. A.; Pritzl, B. J.; Layden, A.; Gregorsok, J.; Welch, D. L.; Webb, T.We present BV photometry and the results of a search for stellar variability in the Galactic globular cluster M 69. The resulting color-magnitude diagram shows significant contamination by field stars. In our variability search we found 62 variable stars, 54 of which were new discoveries....
- ItemThe globular cluster NGC 5286: color-magnitude diagram and variable stars(2010) Zorotovic, M.; Catelan, Marcio; Zoccali, M.; Smith, H. A.; Pritzl, B. J.We present BV photometry and the results of a search for stellar variability in the globular cluster NGC 5286, which has tentatively been associated with the Canis Major dwarf spheroidal galaxy. Our results indicate an Oosterhoff type II for the cluster, which is unusual for an object of extragalactic origin....
- ItemThe Sagittarius dSph globular cluster system: variable stars(2006) Salinas, R.; Catelan, Marcio; Smith, H. A.; Pritzl, B. J.; Borissova, J.We have applied the image subtraction technique to images of four globular clusters which have been suggested to be associated with the Sagittarius dSph galaxy: Arp, NGC634, Palomar2 and Terzan. As a result we have a found a sizeable population of variable stars incluiding RR Lyrae and SX Phoenicis stars in the globular clusters Arp, NGC634 and Terzan. We do not confirm the presence of variable stars that has been previously claimed in Palomar2. In NGC634 we have found 19 RR Lyrae stars (six previously known), and 1 SXstar. Although the real amplitudes of all the variables are not completely determined, the Bailey diagram for the RRab stars, together with the mean of its periods <P_{ab}> = 0.639 d, confirm the Oosterhoff II classification for this cluster. In Arp 2 we have found 9 RRL stars (four previously known) and 3 SXPhe stars. If we only consider the mean period of the RRab stars, <P_{ab}> = 0.593 d, we can classify this cluster as Oosterhoff-intermediate. However, the Bailey diagram does not support this classification, because only one out of eight RRab stars are located in the intermediate region. The RRL specific frequency for this cluster is S_{RR} = 68.8, the highest of all Sagittarius-related globulars, which could be a hint that some of the studied RRL are not Arp members but rather Sagittarius field stars....
- ItemVariable stars in Fornax dwarf spheroidal galaxy(2005) Greco, C.; Clementini, G.; Held, E. V.; Poretti, E.; Catelan, Marcio; Dell'Arciprete, L.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Smith, H. A.; Pritzl, B. J.; Rest, A.; De Lee, N.We present the first results of a variable star search in the field and in the globular clusters of the Fornax dwarf spheroidal galaxy. Variable stars were identified using the Image Subtraction Technique (Alard 2000) on time-series data obtained with the ESO 2.2 m and the Magellan 6.5 m telescopes. The variable star sample includes RR Lyrae stars, Dwarf Cepheids and Anomalous Cepheids. The pulsation properties (namely: periods, light curves, period-amplitude relations and classification in Oosterhoff types) of Fornax variables from the present study are discussed in some detail....
- ItemVariable Stars in Large Magellanic Cloud Globular Clusters. III. Reticulum(2013) Kuehn, C. A.; Dame, K.; Smith, H. A.; Catelan, Márcio; Walker, A. R.; Kunder, A.; Pritzl, B. J.; De Lee, N.; Borissova, J.
- ItemVariable Stars in Sagittarius Globular Clusters. I. Arp 2(2019) Pritzl, B. J.; Gehrman, T. C.; Salinas, R.; Catelan, Márcio; Smith, H. A.; Borissova, J.
- ItemVariable Stars in the Globular Clusters and in the Field of the Fornax dSph Galaxy(2009) Greco, C.; Clementini, G.; Held, E. V.; Poretti, E.; Catelan, Marcio; Dell'Arciprete, L.; Gullieuszik, M.; Maio, M.; Rizzi, L.; Smith, H. A.; Pritzl, B. J.; Rest, A.; de Lee, N.Variable stars have been identified for the first time in Fornax 4, the globular cluster located near the center of the Fornax dwarf spheroidal galaxy. By applying the image-subtraction technique to B and V time series photometry obtained with the MagIC camera of the 6.5 m Magellan Clay telescope and with the wide field imager of the 4 m Blanco CTIO telescope, we detected 27 RR Lyrae stars (22 fundamental-mode, 3 first-overtone, and 2 double-mode pulsators) in a 2.4'×2.4' area centered on Fornax 4. The average and minimum periods of the ab-type RR Lyrae stars, =0.594 days and Pab,min=0.5191 days, respectively, as well as the revised position of the cluster in the horizontal branch type-metallicity plane, all consistently point to an Oosterhoff-intermediate status for the cluster, unlike what is seen for the vast majority of Galactic globular clusters, but in agreement with previous indications for the other globular clusters in Fornax. The average apparent magnitude of the RR Lyrae stars located within 30" from the cluster center is =21.43+/-0.03 mag (σ=0.10 mag, average of 12 stars), leading to a true distance modulus of μ0=20.64+/-0.09 mag or μ0=20.53+/-0.09 mag, depending on whether a low ([Fe/H]=-2.0) or a moderately high ([Fe/H]=-1.5) metallicity is adopted.
- ItemVariable Stars in the Inner Region of NGC 6388(2005) Pritzl, B. J.; Stetson, P. B.; Smith, H. A.; Catelan, Marcio; Layden, A. C.; Kinemuchi, K.; Rich, R. M.; Sweigart, A. V.The metal-rich globular clusters NGC 6388 and NGC 6441 ([Fe/H] ∼-0.6) have unusual sloping blue horizontal branches that extend from a prominent red clump through the RR Lyrae instability strip to a well-populated blue tail. The RR Lyrae variables found from ground-based studies in these clusters have unusually long periods for their metallicities and may represent a new Oosterhoff group. As part of a Hubble Space Telescope Snapshot program we have obtained ACS images of the inner, compact region of NGC 6388 and use archival WFPC2 images to search for additional variable stars. Here we present the results of this variable star search. The properties of the newly discovered RR Lyrae variables will be used to further define the nature of these unusual globular clusters. We gratefully acknowledge financial support through the HST grant GO-09821.09-A.
- ItemVariable Stars in the LMC Globular Cluster NGC 1754(2006) Kuehn, Charles A., III; Taylor, L.; Smith, H. A.; Catelan, Marcio; Pritzl, B. J.; De Lee, N.We have used BVI observations taken with the SMARTS 1.3m telescope and with the SOAR telescope to identify variable stars in the vicinity of the old LMC cluster NGC 1754. We present light curves and periods for the variables and classify the variables according to type. The probability that the RR Lyrae stars found in the neighborhood of NGC 1754 actually belong to the cluster is discussed. Unlike most globular clusters of the Milky Way halo, many of the old star clusters of the LMC have Oosterhoff intermediate properties. The Oosterhoff classification of field and cluster RR Lyrae stars near NGC 1754 is considered. We thank the NSF for partial support of this research....