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Full-Text Articles in Stars, Interstellar Medium and the Galaxy
Discovery Of An Apparent High Latitude Galactic Supernova Remnant, Robert A. Fesen, Jack M. M. Neustadt, Christine S. Black, Ari H. D. Koeppel
Discovery Of An Apparent High Latitude Galactic Supernova Remnant, Robert A. Fesen, Jack M. M. Neustadt, Christine S. Black, Ari H. D. Koeppel
Dartmouth Scholarship
Deep Hα images of a faint emission complex 4.0 x 5.5 degrees in angular extent and located far off the Galactic plane at l = 70.0 degrees, b=-21.5 degrees reveal numerous thin filaments suggestive of a supernova remnant's shock emission. Low dispersion optical spectra covering the wavelength range 4500 - 7500 A show only Balmer line emissions for one filament while three others show a Balmer dominated spectrum along with weak [N I] 5198, 5200 A, [O I] 6300, 6364 A, [N II] 6583 A, [S II] 6716, 6731 A and in one case [O III] 5007 A line emission. …
The Acs Survey Of Globular Clusters. Xiii. Photometric Calibration In Comparison With Stetson Standards, Maren Hempel, Ata Sarajedini, Jay Anderson, Antonio Aparicio, Luigi R. Bedin, Brian Chaboyer
The Acs Survey Of Globular Clusters. Xiii. Photometric Calibration In Comparison With Stetson Standards, Maren Hempel, Ata Sarajedini, Jay Anderson, Antonio Aparicio, Luigi R. Bedin, Brian Chaboyer
Dartmouth Scholarship
In this study we compare the photometric data of 34 Milky Way globular clusters, observed within the Advanced Camera for Surveys (ACS) Treasury Program (PI: A. Sarajedini) with the corresponding ground-based data, provided by the Photometric Standard Field Catalogs of Stetson. We focus on the transformation between the Hubble Space Telescope/ACS F606W to V-band and F814W to I-band only. The goal is to assess the validity of the filter transformation equations by Sirianni et al. with respect to their dependence on metallicity, horizontal branch morphology, mass, and integrated (V – I) color of the various …
Star Formation And Substructure In Galaxy Clusters, Seth A. Cohen, Ryan C. Hickox, Gary A. Wegner, Maret Einasto, Jaan Vennik
Star Formation And Substructure In Galaxy Clusters, Seth A. Cohen, Ryan C. Hickox, Gary A. Wegner, Maret Einasto, Jaan Vennik
Dartmouth Scholarship
We investigate the relationship between star formation (SF) and substructure in a sample of 107 nearby galaxy clusters using data from the Sloan Digital Sky Survey (SDSS). Several past studies of individual galaxy clusters have suggested that cluster mergers enhance cluster SF, while others find no such relationship. The SF fraction in multi-component clusters (0.228 +/- 0.007) is higher than that in single-component clusters (0.175 +/- 0.016) for galaxies with M^0.1_r < -20.5. In both single- and multi-component clusters, the fraction of star-forming galaxies increases with clustercentric distance and decreases with local galaxy number density, and multi-component clusters show a higher SF fraction than single-component clusters at almost all clustercentric distances and local densities. Comparing the SF fraction in individual clusters to several statistical measures of substructure, we find weak, but in most cases significant at greater than 2 sigma, correlations between substructure and SF fraction. These results could indicate that cluster mergers may cause weak but significant SF enhancement in clusters, or unrelaxed clusters exhibit slightly stronger SF due to their less evolved states relative to relaxed clusters.
The Sn 393-Snr Rx J1713.7-3946 (G347.3-0.5) Connection, Robert A. Fesen, Richard Kremer, Daniel Patnaude, Dan Milisavljevic
The Sn 393-Snr Rx J1713.7-3946 (G347.3-0.5) Connection, Robert A. Fesen, Richard Kremer, Daniel Patnaude, Dan Milisavljevic
Dartmouth Scholarship
Although the connection of the Chinese "guest" star of 393 AD with the Galactic supernova remnant RX J1713.7-3946 (G347.3-0.5) made by Wang et al. in 1997 is consistent with the remnant's relatively young properties and the guest star's projected position within the "tail" of the constellation Scorpius, there are difficulties with such an association. The brief Chinese texts concerning the 393 AD guest star make no comment about its apparent brightness, stating only that it disappeared after eight months. However, at the remnant's current estimated 1-1.3 kpc distance and A V 3, its supernova (SN) should have been a visually …
An Oosterhoff Analysis Of The Galactic Bulge Field Rr Lyrae Stars: Implications On Their Absolute Magnitudes, Andrea Kunder, Brian Chaboyer
An Oosterhoff Analysis Of The Galactic Bulge Field Rr Lyrae Stars: Implications On Their Absolute Magnitudes, Andrea Kunder, Brian Chaboyer
Dartmouth Scholarship
We present an analysis of the period-V-amplitude plane for RR0 Lyrae stars (fundamental mode pulsators) with "normal" light curves in the bulge using the MACHO bulge fields. Although bulge globular clusters (GCs) have RR Lyraes that divide into two reasonable distinct groups according to the average period of the RR0 Lyraes, there is no evidence of a gap between Oosterhoff I (OoI) and II (OoII) stars in the bulge field star sample. The majority of the bulge RR0 Lyrae field star population have a difference in period compared to the OoI cluster M3 (Δlog P) that is …
Kinematics Of X‐Ray–Emitting Components In Cassiopeia A, Tracey Delaney, Lawrence Rudnick, Robert A. Fesen, T. W. Jones
Kinematics Of X‐Ray–Emitting Components In Cassiopeia A, Tracey Delaney, Lawrence Rudnick, Robert A. Fesen, T. W. Jones
Dartmouth Scholarship
We present high-resolution X-ray proper-motion measurements of Cassiopeia A using Chandra X-Ray Observatory observations from 2000 and 2002. We separate the emission into four spectrally distinct classes: Si-dominated, Fe-dominated, low-energy-enhanced, and continuum-dominated. These classes also represent distinct spatial and kinematic components. The Si- and Fe-dominated classes are ejecta and have a mean expansion rate of 0.2% yr-1. This is the same as for the forward shock filaments but less than the 0.3% yr-1 characteristic of optical ejecta. The low-energy-enhanced spectral class possibly illuminates a clumpy circumstellar component and has a mean expansion rate of 0.05% yr-1. The continuum-dominated emission likely …