Search Publications
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…
Infrared Selection of Obscured Active Galactic Nuclei in the COSMOS Field
Kartaltepe, Jeyhan S.; Tang, Ji-Jia; Juneau, Stéphanie +13 more
We present a study of the connection among black hole accretion, star formation, and galaxy morphology at z≤slant 2.5. We focus on active galactic nuclei (AGNs) selected by their mid-IR power-law emission. By fitting optical to far-IR photometry with state-of-the-art spectral energy distribution (SED) techniques, we derive stellar masses, star for…
Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 03
Langevin, Y.; Jorda, L.; Lamy, P. L. +67 more
On 2016 July 03, several instruments onboard ESA's Rosetta spacecraft detected signs of an outburst event on comet 67P, at a heliocentric distance of 3.32 au from the Sun, outbound from perihelion. We here report on the inferred properties of the ejected dust and the surface change at the site of the outburst. The activity coincided with the local…
Conjoined constraints on modified gravity from the expansion history and cosmic growth
Nesseris, Savvas; Basilakos, Spyros
In this paper we present conjoined constraints on several cosmological models from the expansion history H (z ) and cosmic growth f σ8. The models we study include the CPL w0wa parametrization, the holographic dark energy (HDE) model, the time-varying vacuum (ΛtCDM ) model, the Dvali, Gabadadze and Porra…
Partial redistribution in 3D non-LTE radiative transfer in solar-atmosphere models
Leenaarts, Jorrit; Sukhorukov, Andrii V.
Context. Resonance spectral lines such as H I Ly α, Mg II H&K, and Ca II H&K that form in the solar chromosphere, are influenced by the effects of 3D radiative transfer as well as partial redistribution (PRD). So far no one has modeled these lines including both effects simultaneously owing to the high computing demands of existing algorit…
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,…
Herschel -ATLAS: revealing dust build-up and decline across gas, dust and stellar mass selected samples - I. Scaling relations
Ivison, R. J.; Baes, M.; Baker, A. J. +19 more
We present a study of the dust, stars and atomic gas (H I) in an H I-selected sample of local galaxies (z < 0.035) in the Herschel Astrophysical Terahertz Large Area Survey fields. This H I-selected sample reveals a population of very high gas fraction (>80 per cent), low stellar mass sources that appear to be in the earliest stages of their…
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…
Detection of nanoflare-heated plasma in the solar corona by the FOXSI-2 sounding rocket
Krucker, Säm; Narukage, Noriyuki; Glesener, Lindsay +4 more
The processes that heat the solar and stellar coronae to several million kelvins, compared with the much cooler photosphere (5,800 K for the Sun), are still not well known1. One proposed mechanism is heating via a large number of small, unresolved, impulsive heating events called nanoflares2. Each event would heat and cool qu…