Search Publications
Asteroid Belts in Debris Disk Twins: Vega and Fomalhaut
Hughes, A. Meredith; Wilner, David J.; Rieke, George H. +8 more
Vega and Fomalhaut are similar in terms of mass, ages, and global debris disk properties; therefore, they are often referred to as "debris disk twins." We present Spitzer 10-35 µm spectroscopic data centered at both stars and identify warm, unresolved excess emission in the close vicinity of Vega for the first time. The properties of the war…
Evolution of the Stellar-to-dark Matter Relation: Separating Star-forming and Passive Galaxies from z = 1 to 0
Leauthaud, Alexie; Massey, Richard; Rhodes, Jason +5 more
We use measurements of the stellar mass function, galaxy clustering, and galaxy-galaxy lensing within the COSMOS survey to constrain the stellar-to-halo mass relation (SHMR) of star forming and quiescent galaxies over the redshift range z = [0.2, 1.0]. For massive galaxies, M * >~ 1010.6 M ⊙, our results indicat…
Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies with Relatively Old Stellar Populations at z ~ 2
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +10 more
Quiescent galaxies at z ~ 2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically…
The Metal Aversion of Long-duration Gamma-Ray Bursts
Fruchter, A. S.; Graham, J. F.
Recently, it has been suggested that the metallicity aversion of Long-duration Gamma Ray Bursts (LGRBs) is not intrinsic to their formation, but rather a consequence of the anti-correlation between star formation and metallicity seen in the general galaxy population. To investigate this proposal, we compare the metallicity of the hosts of LGRBs, b…
Implications of Mass and Energy Loss due to Coronal Mass Ejections on Magnetically Active Stars
Drake, Jeremy J.; Gopalswamy, Nat; Yashiro, Seiji +1 more
Analysis of a database of solar coronal mass ejections (CMEs) and associated flares over the period 1996-2007 finds well-behaved power-law relationships between the 1-8 Å flare X-ray fluence and CME mass and kinetic energy. We extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to CMEs from s…
The Driver of Coronal Mass Ejections in the Low Corona: A Flux Rope
Liu, Y.; Cheng, X.; Ding, M. D. +2 more
Recent Solar Dynamic Observatory observations reveal that coronal mass ejections (CMEs) consist of a multi-temperature structure: a hot flux rope and a cool leading front (LF). The flux rope first appears as a twisted hot channel in the Atmospheric Imaging Assembly (AIA) 94 Å and 131 Å passbands. The twisted hot channel initially lies along the po…
STIS Coronagraphic Imaging of Fomalhaut: Main Belt Structure and the Orbit of Fomalhaut b
Kalas, Paul; Fitzgerald, Michael P.; Graham, James R. +1 more
We present new optical coronagraphic data of Fomalhaut obtained with HST/STIS in 2010 and 2012. Fomalhaut b is recovered at both epochs to high significance. The observations include the discoveries of tenuous nebulosity beyond the main dust belt detected to at least 209 AU projected radius, and a ~50 AU wide azimuthal gap in the belt northward of…
The Deep Blue Color of HD 189733b: Albedo Measurements with Hubble Space Telescope/Space Telescope Imaging Spectrograph at Visible Wavelengths
Sing, David K.; Evans, Thomas M.; Aigrain, Suzanne +7 more
We present a secondary eclipse observation for the hot Jupiter HD 189733b across the wavelength range 290-570 nm made using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. We measure geometric albedos of Ag = 0.40 ± 0.12 across 290-450 nm and Ag < 0.12 across 450-570 nm at 1σ confidence. The albedo …
Constraining the Assembly of Normal and Compact Passively Evolving Galaxies from Redshift z = 3 to the Present with CANDELS
Ryan, R. E.; Giavalisco, M.; Koekemoer, A. +16 more
We study the evolution of the number density, as a function of the size, of passive early-type galaxies (ETGs) with a wide range of stellar masses (1010 M ⊙ < M * <~ 1011.5 M ⊙) from z ~ 3 to z ~ 1, exploiting the unique data set available in the GOODS-South field, including the recently…
Evidence for CO Shock Excitation in NGC 6240 from Herschel SPIRE Spectroscopy
Veilleux, S.; Sanders, D. B.; Armus, L. +28 more
We present Herschel SPIRE FTS spectroscopy of the nearby luminous infrared galaxy NGC 6240. In total 20 lines are detected, including CO J = 4 - 3 through J = 13 - 12, 6 H2O rotational lines, and [C I] and [N II] fine-structure lines. The CO to continuum luminosity ratio is 10 times higher in NGC 6240 than Mrk 231. Although the CO ladde…