Search Publications
Constraints on Quenching of Z ≲ 2 Massive Galaxies from the Evolution of the Average Sizes of Star-forming and Quenched Populations in COSMOS
Ilbert, O.; Scoville, N. Z.; Carollo, C. M. +5 more
We use >9400 {log}(m/{M}⊙ )> 10 quiescent and star-forming galaxies at z ≲ 2 in COSMOS/UltraVISTA to study the average size evolution of these systems, with focus on the rare ultra-massive population at {log}(m/{M}⊙ )> 11.4. The large 2 square degree survey area delivers a sample of ∼400 such ultra-massive systems. A…
ALMA Measurements of Circumstellar Material in the GQ Lup System
Herczeg, Gregory J.; MacGregor, Meredith A.; Wilner, David J. +7 more
We present Atacama Large Millimeter/submillimeter Array observations of the GQ Lup system, a young Sun-like star with a substellar-mass companion in a wide-separation orbit. These observations of 870 µm continuum and CO J = 3-2 line emission with beam size ∼0.″3 (∼45 au) resolve the disk of dust and gas surrounding the primary star, GQ Lup A…
The Solar Energetic Particle Event of 2010 August 14: Connectivity with the Solar Source Inferred from Multiple Spacecraft Observations and Modeling
Thompson, B. J.; Lario, D.; Kwon, R. -Y. +13 more
We analyze one of the first solar energetic particle (SEP) events of solar cycle 24 observed at widely separated spacecraft in order to assess the reliability of models currently used to determine the connectivity between the sources of SEPs at the Sun and spacecraft in the inner heliosphere. This SEP event was observed on 2010 August 14 by near-E…
A Comet Active Beyond the Crystallization Zone
Mutchler, Max; Jewitt, David; Agarwal, Jessica +3 more
We present observations showing inbound long-period comet C/2017 K2 (PANSTARRS) to be active at a record heliocentric distance. Nucleus temperatures are too low (60-70 K) either for water ice to sublimate or for amorphous ice to crystallize, requiring another source for the observed activity. Using the Hubble Space Telescope we find a sharply boun…
A Parameter Study for Modeling Mg II h and k Emission during Solar Flares
Kleint, Lucia; Rubio da Costa, Fatima
Solar flares show highly unusual spectra in which the thermodynamic conditions of the solar atmosphere are encoded. Current models are unable to fully reproduce the spectroscopic flare observations, especially the single-peaked spectral profiles of the Mg II h and k lines. We aim to understand the formation of the chromospheric and optically thick…
HST Imaging of the Brightest z ∼ 8-9 Galaxies from UltraVISTA: The Extreme Bright End of the UV Luminosity Function
Holwerda, Benne W.; Franx, Marijn; Illingworth, Garth D. +13 more
We report on the discovery of three especially bright candidate {z}{phot}≳ 8 galaxies. Five sources were targeted for follow-up with the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3), selected from a larger sample of 16 bright (24.8≲ H≲ 25.5 mag) candidate z≳ 8 Lyman break galaxies (LBGs) identified over 1.6 degrees2
Morphology Dependence of Stellar Age in Quenched Galaxies at Redshift ∼1.2: Massive Compact Galaxies Are Older than More Extended Ones
Giavalisco, Mauro; Bezanson, Rachel; Williams, Christina C. +6 more
We report the detection of morphology-dependent stellar age in massive quenched galaxies (QGs) at z ∼ 1.2. The sense of the dependence is that compact QGs are 0.5-2 Gyr older than normal-sized ones. The evidence comes from three different age indicators—{D}n4000, {{{H}}}δ , and fits to spectral synthesis models—applied to the…
Observations and Numerical Models of Solar Coronal Heating Associated with Spicules
De Pontieu, B.; McIntosh, S. W.; De Moortel, I. +1 more
Spicules have been proposed as significant contributors to the mass and energy balance of the corona. While previous observations have provided a glimpse of short-lived transient brightenings in the corona that are associated with spicules, these observations have been contested and are the subject of a vigorous debate both on the modeling and the…
Searching for Rapid Orbital Decay of WASP-18b
Wilkins, Ashlee N.; Deming, Drake; Delrez, Laetitia +4 more
The WASP-18 system, with its massive and extremely close-in planet, WASP-18b (M p = 10.3M J , a = 0.02 au, P = 22.6 hr), is one of the best-known exoplanet laboratories to directly measure Q‧, the modified tidal quality factor and proxy for efficiency of tidal dissipation, of the host star. Previous analysis predicted a ra…
Stellar Clusterings around "Isolated" Massive YSOs in the LMC
Ott, Jürgen; Hughes, Annie; Weisz, Daniel R. +10 more
Observations suggest that there is a significant fraction of O stars in the field of the Milky Way that appear to have formed in isolation or in low-mass clusters (<100 {M}⊙ ). The existence of these high-mass stars that apparently formed in the field challenges the generally accepted paradigm, which requires star formation to occur …