Search Publications
HST Astrometry in the 30 Doradus Region: Measuring Proper Motions of Individual Stars in the Large Magellanic Cloud
Anderson, Jay; van der Marel, Roeland P.; Sana, Hugues +5 more
We present measurements of positions and relative proper motions in the 30 Doradus region of the LMC. We detail the construction of a single-epoch astrometric reference frame, based on specially designed observations obtained with the two main imaging instruments Advanced Camera for Surveys/Wide Field Channel and Wide Field Camera 3/UVIS on board …
Uncovering the Nucleus Candidate for NGC 253
Schirmer, M.; Díaz, R. J.; Günthardt, G. I. +4 more
NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong …
Pursuing the Planet-Debris Disk Connection: Analysis of Upper Limits from the Anglo-Australian Planet Search
Wittenmyer, Robert A.; Marshall, Jonathan P.
Solid material in protoplanetary disks will suffer one of two fates after the epoch of planet formation; either being bound up into planetary bodies, or remaining in smaller planetesimals to be ground into dust. These end states are identified through detection of sub-stellar companions by periodic radial velocity (or transit) variations of the st…
Cepheid Variables in the Maser-host Galaxy NGC 4258
Macri, Lucas M.; Hoffmann, Samantha L.
We present results of a ground-based survey for Cepheid variables in NGC 4258. This galaxy plays a key role in the Extragalactic Distance Scale due to its very precise and accurate distance determination via very long baseline interferometry observations of water masers. We imaged two fields within this galaxy using the Gemini North telescope and …
Metallicity Distribution Functions of Four Local Group Dwarf Galaxies
Holtzman, Jon; Anthony-Twarog, Barbara J.; Saha, Abhijit +1 more
We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, (1) matching stars to isochrones in color-color …
An Emerging Wolf-Rayet Massive Star Cluster in NGC 4449
Johnson, Kelsey E.; Indebetouw, Rémy; Reines, Amy E. +1 more
We present a panchromatic investigation of the partially embedded, emerging massive cluster Source 26 (=S26) in NGC 4449 with optical spectra obtained at Apache Point Observatory and archival Hubble, Spitzer, and Herschel 5 Space Telescope images. First identified as a radio continuum source with a thermal component due to ionized mater…
The Optical Wind Line Variability of η Carinae During the 2009.0 Event
Gull, T. R.; Gies, D. R.; Richardson, N. D. +2 more
We report on high-resolution spectroscopy of the 2009.0 spectroscopic event of η Carinae collected via SMARTS observations using the CTIO 1.5 m telescope and echelle spectrograph. Our observations were made almost every night over a two-month interval around the photometric minimum of η Car associated with the periastron passage of a hot companion…
Discovery of Nine Extended Ionized Gas Clouds in a z = 0.4 Cluster
Gu, Liyi; Koyama, Yusei; Kodama, Tadayuki +4 more
From deep Hα imaging data of Suprime-Cam/Subaru, we discovered nine extended ionized gas clouds (EIG) around galaxies in the Abell 851 cluster (A851) at z = 0.4. We surveyed a 30 × 25 arcmin region, and the EIGs were found only near the cluster center (\lt 2.3 arcmin ∼ 750 kpc). The parent galaxies of the EIGs are star-forming or post-starburst ga…
Pan-Chromatic Observations of the Remarkable Nova Large Magellanic Cloud 2012
Walter, Frederick M.; Drake, Jeremy J.; Woodward, Charles E. +9 more
We present the results of an intensive multiwavelength campaign on nova LMC 2012. This nova evolved very rapidly in all observed wavelengths. The time to fall two magnitudes in the V band was only 2 days. In X-rays the super soft phase began 13 ± 5 days after discovery and ended around day 50 after discovery. During the super soft phase, the Swift…
An X-Ray Flare from 47 Cas
Karmakar, Subhajeet; Pandey, Jeewan C.
Using XMM-Newton observations, we investigate properties of a flare from the very active but poorly known stellar system 47 Cas. The luminosity at the peak of the flare is found to be 3.54 × 1030 erg {{s}-1}, which is ∼2 times higher than that at a quiescent state. The quiescent state corona of 47 Cas can be represented by tw…