Search Publications
Far-UV Spectroscopy of the Planet-hosting Star WASP-13: High-energy Irradiance, Distance, Age, Planetary Mass-loss Rate, and Circumstellar Environment
France, K.; Fossati, L.; Lendl, M. +3 more
Several transiting hot Jupiters orbit relatively inactive main-sequence stars. For some of those, the {log}{R}{HK}\prime activity parameter lies below the basal level (-5.1). Two explanations have been proposed so far: (i) the planet affects the stellar dynamo, (ii) the {log}{R}{HK}\prime measurements …
X-Ray Emissivity of Old Stellar Populations: A Local Group Census
Jones, Christine; Wang, Q. Daniel; Kraft, Ralph P. +6 more
We study the unresolved X-ray emission in three Local Group dwarf elliptical (dE) galaxies (NGC 147, NGC 185, and NGC 205) using XMM-Newton observations; this emission most likely originates from a collection of weak X-ray sources, mainly cataclysmic variables and coronally active binaries. Precise knowledge of this stellar X-ray emission is cruci…
The Star Cluster System in the Local Group Starburst Galaxy IC 10
Lee, Myung Gyoon; Lim, Sungsoon
We present a survey of star clusters in the halo of IC 10, a starburst galaxy in the Local Group, based on Subaru R-band images and NOAO Local Group Survey UBVRI images. We find five new star clusters. All of these star clusters are located far from the center of IC 10, while previously known star clusters are mostly located in the main body. Inte…
Gemini Planet Imager Observations of the AU Microscopii Debris Disk: Asymmetries within One Arcsecond
Matthews, Brenda C.; Duchêne, Gaspard; Esposito, Thomas M. +42 more
We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in …
The Born-again Planetary Nebula A78: An X-Ray Twin of A30
Gruendl, R. A.; Hamann, W. -R.; Chu, Y. -H. +8 more
We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar …
Newly Determined Explosion Center of Tycho's Supernova and the Implications for Proposed Ex-companion Stars of the Progenitor
Schaefer, Bradley E.; Xue, Zhichao
“Star G,” near the center of the supernova remnant of Tycho’s SN 1572, has been claimed to be the ex-companion star of the exploding white dwarf, thus pointing to the progenitor being like a recurrent nova. This claim has been controversial, but there have been no confident proofs or disproofs. Previously, no one has seriously addressed the questi…
The 1999aa-like Type Ia Supernova iPTF14bdn in the Ultraviolet and Optical
Suntzeff, Nicholas B.; Wang, Xiaofeng; Zhang, Jujia +5 more
We present ultraviolet (UV) and optical photometry and spectra of the 1999aa-like supernova (SN) iPTF14bdn. The UV data were observed using the Swift Ultraviolet/Optical Telescope and constitute the first UV spectral series of a 1999aa-like SN. From the photometry, we measure Δm15(B) = 0.84 ± 0.05 mag and blue UV colors at epochs earlie…
A Herschel/HIFI Legacy Survey of HF and H2O in the Galaxy: Probing Diffuse Molecular Cloud Chemistry
Gerin, M.; Neufeld, D. A.; Sonnentrucker, P. +5 more
We combine Herschel observations for a total of 12 sources to construct the most uniform survey of HF and H2O in our Galactic disk. Both molecules are detected in absorption along all sight lines. The high spectral resolution of the Heterodyne Instrument for the Far-infrared (HIFI) allows us to compare the HF and H2O distribu…
The Relation between Dynamical Mass-to-light Ratio and Color for Massive Quiescent Galaxies out to z ~ 2 and Comparison with Stellar Population Synthesis Models
van Dokkum, Pieter G.; Franx, Marijn; Bezanson, Rachel +2 more
We explore the relation between the dynamical mass-to-light ratio (M/L) and rest-frame color of massive quiescent galaxies out to z ~ 2. We use a galaxy sample with measured stellar velocity dispersions in combination with Hubble Space Telescope and ground-based multi-band photometry. Our sample spans a large range in log M dyn/L g…
Hunting for Orphaned Central Compact Objects among Radio Pulsars
Ng, C. -Y.; Ho, W. C. G.; Bogdanov, S. +3 more
Central compact objects (CCOs) are a handful of young neutron stars found at the center of supernova remnants (SNRs). They show high thermal X-ray luminosities but no radio emission. Spin-down rate measurements of three CCOs with X-ray pulsations indicate surface dipole fields much weaker than those of typical young pulsars. To investigate if CCOs…