Search Publications
Mapping the Interstellar Reddening and Extinction toward Baade’s Window Using Minimum Light Colors of ab-type RR Lyrae Stars: Revelations from the De-reddened Color-Magnitude Diagrams
Cenko, S. Bradley; Cunha, Katia; Olsen, Knut +21 more
We have obtained repeated images of six fields toward the Galactic bulge in five passbands (u, g, r, i, z) with the DECam imager on the Blanco 4 m telescope at CTIO. From more than 1.6 billion individual photometric measurements in the field centered on Baade’s window, we have detected 4877 putative variable stars. A total of 474 of these have bee…
Evidence for Inside-out Galaxy Growth and Quenching of a z ∼ 2 Compact Galaxy From High-resolution Molecular Gas Imaging
Weiner, Benjamin J.; Bezanson, Rachel; Williams, Christina C. +2 more
We present high spatial resolution imaging of the CO(1-0) line from the Karl G. Jansky Very Large Array of COSMOS 27289, a massive, compact star-forming galaxy (SFG) at z = 2.234. This galaxy was selected because of its structural similarity to z ∼ 2 passive galaxies. Our previous observations showed that it is very gas poor with respect to typica…
New Hot Subdwarf Stars Identified in Gaia DR2 with LAMOST DR5 Spectra. II.
Zhao, Gang; Németh, Péter; Zhao, Jingkun +1 more
Three hundred and eighty eight hot subdwarf stars have been identified by using the Hertzsprung-Russell (HR) diagram built from the second data release of the Gaia mission. By analyzing their observed Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra, we characterized 186 sdB, 73 He-sdOB, 65 sdOB, 45 sdO, 12 He-sdO, and 7 …
Star-density Profiles of Six Old Star Clusters in the Large Magellanic Cloud
Cadelano, Mario; Pallanca, Cristina; Dalessandro, Emanuele +6 more
We used resolved star counts from Hubble Space Telescope (HST) images to determine the center of gravity and the projected density profiles of six old globular clusters (GCs) in the Large Magellanic Cloud (LMC), namely NGC 1466, NGC 1841, NGC 1898, NGC 2210, NGC 2257, and Hodge 11. For each system, the LMC field contribution was properly taken int…
PLCK G165.7+67.0: Analysis of a Massive Lensing Cluster in a Hubble Space Telescope Census of Submillimeter Giant Arcs Selected Using Planck/Herschel
Donahue, Megan; Frye, Brenda L.; Conselice, Christopher J. +19 more
We present Hubble Space Telescope WFC3-IR imaging in the fields of six apparently bright dusty star-forming galaxies (DSFGs) at z = 2-4 identified by their rest-frame far-infrared colors using the Planck and Herschel space facilities. We detect near-infrared counterparts for all six submillimeter sources, allowing us to undertake strong-lensing an…
How Much Information Does the Sodium Doublet Encode? Retrieval Analysis of Non-LTE Sodium Lines at Low and High Spectral Resolutions
Heng, Kevin; Fisher, Chloe
Motivated by both ground- and space-based detections of the sodium doublet in the transmission spectra of exoplanetary atmospheres, we revisit the theory and interpretation of sodium lines in non-local thermodynamic equilibrium (NLTE), where collisions are not efficient enough to maintain a Boltzmann distribution for the excited and ground states …
Detailed Chemical Composition and Orbit of the Newly Discovered Globular Cluster FSR 1758: Implications for the Accretion of the Sequoia Dwarf Galaxy onto the Milky Way
Minniti, Dante; Geisler, Doug; Villanova, Sandro +4 more
We present detailed chemical abundances, radial velocity, and orbital parameters for FSR 1758, a recently discovered massive cluster in the direction of the Galactic bulge. High-resolution (R ∼ 42,000) spectra were obtained for nine members using the Magellan/Clay telescope instrumented with the MIKE echelle spectrogragh in the wavelength range of…
The Virgo Overdensity Explained
Newberg, Heidi Jo; Donlon, Thomas, II; Weiss, Jake +2 more
We suggest that the Virgo Overdensity of stars in the stellar halo is the result of a radial dwarf galaxy merger that we call the Virgo Radial Merger. Because the dwarf galaxy passed very near to the Galactic center, the debris has a large range of energies but nearly zero L z angular momentum. The debris appears to extend from 5 to 5…
Weak and Compact Radio Emission in Early High-mass Star-forming Regions. II. The Nature of the Radio Sources
Menten, K. M.; Molinari, S.; Wyrowski, F. +9 more
In this study we analyze 70 radio continuum sources that are associated with dust clumps and which are considered to be candidates for the earliest stages of high-mass star formation. The detection of these sources was reported by Rosero et al., who found most of them to show weak (< 1 mJy) and compact (< 0.″6) radio emission. Herein, we use…
Constraining Mass-transfer Histories of Blue Straggler Stars with COS Spectroscopy of White Dwarf Companions
Sills, Alison; Knigge, Christian; Mathieu, Robert D. +4 more
Recent studies show that the majority of blue straggler stars (BSSs) in old open clusters are formed through mass transfer from an evolved star onto a main-sequence companion, resulting in a BSS and white dwarf (WD) in a binary system. We present constraints on the mass transfer histories of two BSS-WD binaries in the open cluster NGC 188, using W…