Search Publications
On the Factors Determining the Eruptive Character of Solar Flares
Veronig, Astrid M.; Thalmann, Julia K.; Baumgartner, Christian
We investigated how the magnetic field in solar active regions (ARs) controls flare activity, i.e., whether a confined or eruptive flare occurs. We analyzed 44 flares of GOES class M5.0 and larger that occurred during 2011-2015. We used 3D potential magnetic field models to study their location (using the flare distance from the flux-weighted AR c…
First Results from the Herschel and ALMA Spectroscopic Surveys of the SMC: The Relationship between [C II]-bright Gas and CO-bright Gas at Low Metallicity
Warren, Steven R.; Bolatto, Alberto D.; Meixner, Margaret +15 more
The Small Magellanic Cloud (SMC) provides the only laboratory to study the structure of molecular gas at high resolution and low metallicity. We present results from the Herschel Spectroscopic Survey of the SMC (HS3), which mapped the key far-IR cooling lines [C II], [O I], [N II], and [O III] in five star-forming regions, and new ALMA …
The COS CGM Compendium. I. Survey Design and Initial Results
Lehner, Nicolas; Howk, J. Christopher; O'Meara, John M. +3 more
We present a neutral hydrogen-selected absorption-line survey of gas with H I column densities 15< {log}{N}{{H}{{I}}}< 19 at z≲ 1 using the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our main aim is to determine the metallicity distribution of these absorbers. Our sample consists of 224 absorbers selected on the ba…
Hierarchical Fragmentation in the Perseus Molecular Cloud: From the Cloud Scale to Protostellar Objects
Bourke, Tyler L.; Myers, Philip C.; Gutermuth, Robert A. +8 more
We present a study of hierarchical structure in the Perseus molecular cloud, from the scale of the entire cloud (≳ 10 pc) to smaller clumps (∼1 pc), cores (∼0.05-0.1 pc), envelopes (∼300-3000 au), and protostellar objects (∼15 au). We use new observations from the Submillimeter Array (SMA) large project “Mass Assembly of Stellar Systems and their …
An Analytical Diffusion-Expansion Model for Forbush Decreases Caused by Flux Ropes
Dumbović, Mateja; Temmer, Manuela; Vršnak, Bojan +2 more
We present an analytical diffusion-expansion Forbush decrease (FD) model ForbMod, which is based on the widely used approach of an initially empty, closed magnetic structure (i.e., flux rope) that fills up slowly with particles by perpendicular diffusion. The model is restricted to explaining only the depression caused by the magnetic structure of…
The Spatially Resolved Dust-to-metals Ratio in M101
Sandstrom, Karin M.; Johnson, L. Clifton; Leroy, Adam K. +3 more
The dust-to-metals ratio describes the fraction of heavy elements contained in dust grains, and its variation provides key insights into the life cycle of dust. We measure the dust-to-metals ratio in M101, a nearby galaxy with a radial metallicity (Z) gradient spanning ∼1 dex. We fit the spectral energy distribution of dust from 100 to 500 µ…
The Changing-look Quasar Mrk 590 Is Awakening
Vestergaard, M.; Peterson, B. M.; Goad, M. +9 more
Mrk 590 was originally classified as a Seyfert 1 galaxy, but then it underwent dramatic changes: the nuclear luminosity dropped by over two orders of magnitude and the broad emission lines all but disappeared from the optical spectrum. Here we present follow-up observations to the original discovery and characterization of this “changing-look” act…
The Excited Spin State of 1I/2017 U1 ‘Oumuamua
Wainscoat, Richard J.; Weaver, Harold A.; Buie, Marc W. +15 more
We show that ‘Oumuamua’s excited spin could be in a high-energy long axis mode (LAM) state, which implies that its shape could be far from the highly elongated shape found in previous studies. CLEAN and ANOVA algorithms are used to analyze ‘Oumuamua’s lightcurve using 818 observations over 29.3 days. Two fundamental periodicities are found at freq…
Near-infrared High-resolution Imaging Polarimetry of FU Ori-type Objects: Toward a Unified Scheme for Low-mass Protostellar Evolution
Henning, Thomas; Fu, Guangwei; Dong, Ruobing +14 more
We present near-IR imaging polarimetry of five classical FU Ori-type objects (FU Ori, V1057 Cyg, V1515 Cyg, V1735 Cyg, Z CMa) with an ∼0.″1 resolution observed using HiCIAO+AO188 at the Subaru Telescope. We observed scattered light associated with circumstellar dust around four of them (i.e., all but V1515 Cyg). Their polarized intensity distribut…
Homologous Large-amplitude Nonlinear Fast-mode Magnetosonic Waves Driven by Recurrent Coronal Jets
Liu, Yu; Liu, Ying D.; Shen, Yuandeng +3 more
The detailed observational analysis of a homologous extreme-ultraviolet (EUV) wave event is presented to study the driving mechanism and the physical property of the EUV waves, combining high-resolution data taken by the Solar Dynamics Observatory and the Solar TErrestrial RElations Observatory. It is observed that four homologous EUV waves origin…