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An Exo-Kuiper Belt with an Extended Halo around HD 191089 in Scattered Light
Debes, John H.; Schneider, Glenn; Duchêne, Gaspard +70 more
We have obtained Hubble Space Telescope STIS and NICMOS and Gemini/GPI scattered-light images of the HD 191089 debris disk. We identify two spatial components: a ring resembling the Kuiper Belt in radial extent (FWHM ∼ 25 au, centered at ∼46 au) and a halo extending to ∼640 au. We find that the halo is significantly bluer than the ring, consistent…
PDS 70: A Transition Disk Sculpted by a Single Planet
van der Marel, Nienke; Muley, Dhruv; Fung, Jeffrey
The wide, deep cavities of transition disks are often believed to have been hollowed out by nascent planetary systems. PDS 70, a ∼5 Myr old transition disk system in which a multi-Jupiter-mass planet candidate at 22 au coexists with a ∼30 au gas and ∼60 au dust-continuum gap, provides a valuable case study for this hypothesis. Using the PEnGUIn hy…
Dynamical Histories of the Crater II and Hercules Dwarf Galaxies
Simon, Joshua D.; Fu, Sal Wanying; Alarcón Jara, Alex G.
We investigate the possibility that the dwarf galaxies Crater II and Hercules have previously been tidally stripped by the Milky Way. We present Magellan/IMACS spectra of candidate member stars in both objects. We identify 37 members of Crater II, 25 of which have velocity measurements in the literature, and we classify three stars within that sub…
A kilometre-sized Kuiper belt object discovered by stellar occultation using amateur telescopes
Wada, T.; Usui, F.; Ichikawa, K. +7 more
Kuiper belt objects (KBOs) are thought to be remnants of the early Solar System, and their size distribution provides an opportunity to explore the formation and evolution of the outer Solar System1-5. In particular, the size distribution of kilometre-sized (radius = 1-10 km) KBOs represents a signature of initial planetesimal sizes whe…
Extended Main-sequence Turnoffs in the Double Cluster h and χ Persei: The Complex Role of Stellar Rotation
Milone, Antonino P.; Cordoni, Giacomo; Deng, Licai +4 more
Using Gaia Data Release 2 photometry, we report the detection of extended main-sequence turnoff (eMSTO) regions in the color-magnitude diagrams (CMDs) of the ∼14 Myr old double clusters h and χ Persei (NGC 869 and NGC 884). We find that stars with masses below ∼1.3 M ⊙ in both h and χ Persei populate narrow main sequences (MSs), while m…
The Resolved Distributions of Dust Mass and Temperature in Local Group Galaxies
Sandstrom, Karin M.; Leroy, Adam K.; Chiang, I-Da +2 more
We utilize archival far-infrared maps from the Herschel Space Observatory in four Local Group galaxies (Small and Large Magellanic Clouds (SMC and LMC), M31, and M33). We model their spectral energy distribution from 100 to 500 µm using a single-temperature modified blackbody emission with a fixed emissivity index of β = 1.8. From the best-f…
UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer
Jadhav, Vikrant V.; Puzia, Thomas H.; Simunovic, Mirko +7 more
The old open cluster M67, populated with blue straggler stars (BSSs), is a well-known test bed to study the BSS formation pathways. Here, we report the first direct detection of a white dwarf (WD) companion to a BSS in M67, using far-UV images from the Ultra-Violet Imaging telescope on ASTROSAT. Near-simultaneous observations in three far-UV bands…
PAHs as tracers of the molecular gas in star-forming galaxies
Daddi, E.; Elbaz, D.; Gómez-Guijarro, C. +12 more
We combine new CO(1-0) line observations of 24 intermediate redshift galaxies (0.03 < z < 0.28) along with literature data of galaxies at 0 < z < 4 to explore scaling relations between the dust and gas content using polycyclic aromatic hydrocarbon (PAH) 6.2 µm (L6.2), CO (L^' }_CO), and infrared (LIR) lumino…
Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum
Im, M.; Malkan, M. A.; Geier, S. +164 more
We model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the Hubble Space Telescope during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum v…
Carbon depletion observed inside T Tauri inner rims. Formation of icy, kilometer size planetesimals by 1 Myr
McClure, M. K.
Context. The carbon content of protoplanetary disks is an important parameter to characterize planets formed at different disk radii. There is some evidence from far-infrared and submillimeter observations that gas in the outer disk is depleted in carbon, with a corresponding enhancement of carbon-rich ices at the disk midplane. Observations of th…