Search Publications
The PdBI Arcsecond Whirlpool Survey (PAWS): The Role of Spiral Arms in Cloud and Star Formation
Leroy, Adam K.; Meidt, Sharon E.; Hughes, Annie +9 more
The process that leads to the formation of the bright star-forming sites observed along prominent spiral arms remains elusive. We present results of a multi-wavelength study of a spiral arm segment in the nearby grand-design spiral galaxy M51 that belongs to a spiral density wave and exhibits nine gas spurs. The combined observations of the (ioniz…
Evidence for a Time Lag in Solar Modulation of Galactic Cosmic Rays
Tomassetti, Nicola; Orcinha, Miguel; Barão, Fernando +1 more
The solar modulation effect of cosmic rays in the heliosphere is an energy-, time-, and particle-dependent phenomenon that arises from a combination of basic particle transport processes such as diffusion, convection, adiabatic cooling, and drift motion. Making use of a large collection of time-resolved cosmic-ray data from recent space missions, …
Mass-loss Rates from Coronal Mass Ejections: A Predictive Theoretical Model for Solar-type Stars
Cranmer, Steven R.
Coronal mass ejections (CMEs) are eruptive events that cause a solar-type star to shed mass and magnetic flux. CMEs tend to occur together with flares, radio storms, and bursts of energetic particles. On the Sun, CME-related mass loss is roughly an order of magnitude less intense than that of the background solar wind. However, on other types of s…
Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745
Churazov, E.; Zitrin, A.; Rosati, P. +24 more
To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandra observations of the HST Frontier Fields cluster MACS J0717.5+3745. The Chandra image shows a complex merger event, with at least four components belonging to different merging subclusters. Northwest of the cluster,…
Signatures of Nitrogen Chemistry in Hot Jupiter Atmospheres
Madhusudhan, Nikku; MacDonald, Ryan J.
Inferences of molecular compositions of exoplanetary atmospheres have generally focused on carbon, hydrogen, and oxygen-bearing molecules. Recently, additional absorption in Hubble Space Telescope Wide Field Camera 3 (WFC3) transmission spectra around 1.55 µm has been attributed to nitrogen-bearing chemical species: NH3 or HCN. Th…
Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey
Kirkpatrick, J. Davy; Burgasser, Adam J.; Logsdon, Sarah E. +6 more
We combine 131 new medium-resolution (R ∼ 2000) J-band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5-T9. Specifically, we use an established set of spe…
The Mass, Color, and Structural Evolution of Today’s Massive Galaxies Since z ∼ 5
Franx, Marijn; Muzzin, Adam; van Dokkum, Pieter +12 more
In this paper, we use stacking analysis to trace the mass growth, color evolution, and structural evolution of present-day massive galaxies ({log}({M}* /{M}⊙ )=11.5) out to z = 5. We utilize the exceptional depth and area of the latest UltraVISTA data release, combined with the depth and unparalleled seeing of CANDELS to gath…
Connecting Clump Sizes in Turbulent Disk Galaxies to Instability Theory
Glazebrook, Karl; Bolatto, Alberto D.; Obreschkow, Danail +8 more
In this letter we study the mean sizes of Hα clumps in turbulent disk galaxies relative to kinematics, gas fractions, and Toomre Q. We use ∼100 pc resolution HST images, IFU kinematics, and gas fractions of a sample of rare, nearby turbulent disks with properties closely matched to z∼ 1.5{--}2 main-sequence galaxies (the DYNAMO sample). We find li…
The MOSDEF Survey: Metallicity Dependence of PAH Emission at High Redshift and Implications for 24 µm Inferred IR Luminosities and Star Formation Rates at z ∼ 2
Siana, Brian; Shapley, Alice E.; Reddy, Naveen A. +9 more
We present results on the variation of 7.7 µm polycyclic aromatic hydrocarbon (PAH) emission in galaxies spanning a wide range in metallicity at z ∼ 2. For this analysis, we use rest-frame optical spectra of 476 galaxies at 1.37 ≤ z ≤ 2.61 from the MOSFIRE Deep Evolution Field (MOSDEF) survey to infer metallicities and ionization states. Spi…
Hubble Space Telescope Detection of the Millisecond Pulsar J2124-3358 and its Far-ultraviolet Bow Shock Nebula
van Kerkwijk, M. H.; Pavlov, G. G.; Guillot, S. +4 more
We observed the nearby millisecond pulsar J2124-3358 with the Hubble Space Telescope in broad far-UV (FUV) and optical filters. The pulsar is detected in both bands with fluxes F(1250-2000 Å) = (2.5 ± 0.3) × 10-16 erg s-1 cm-2 and F(3800-6000 Å) = (6.4 ± 0.4) × 10-17 erg s-1 cm-2, w…