Search Publications
An Improved Hertzsprung-Russell Diagram for the Orion Trapezium Cluster
Fang, Min; Pascucci, Ilaria; Apai, Dániel +1 more
We present a study of the Trapezium cluster in Orion. We analyze flux-calibrated Very Large Telescope/Multi-Unit Spectroscopic Explorer spectra of 361 stars to simultaneously measure the spectral types, reddening, and the optical veiling due to accretion. We find that the extinction law from Cardelli et al. with a total-to-selective extinction val…
The Effect of Stream Interaction Regions on ICME Structures Observed in Longitudinal Conjunction
Lugaz, Noé; Scolini, Camilla; Galvin, Antoinette B. +1 more
We study two interplanetary coronal mass ejections (ICMEs) observed at Mercury and at 1 au by spacecraft in longitudinal conjunction, investigating the question: what causes the drastic alterations observed in some ICMEs during propagation, while other ICMEs remain relatively unchanged? Of the two ICMEs, the first one propagated relatively self-si…
The IGRINS YSO Survey. I. Stellar Parameters of Pre-main-sequence Stars in Taurus-Auriga
Johns-Krull, Christopher M.; Hwang, Narae; Lee, Jae-Joon +19 more
We present fundamental parameters for 110 canonical K- and M-type (1.3-0.13 M⊙) Taurus-Auriga young stellar objects (YSOs). The analysis produces a simultaneous determination of effective temperature (Teff), surface gravity (log g), magnetic-field strength (B), and projected rotational velocity ( $v\sin i$ ). Our method emplo…
Age-dating Red Giant Stars Associated with Galactic Disk and Halo Substructures
Angus, Ruth; Huber, Daniel; Saunders, Nicholas +12 more
The vast majority of Milky Way stellar halo stars were likely accreted from a small number (≲3) of relatively large dwarf galaxy accretion events. However, the timing of these events is poorly constrained and predominantly relies on indirect dynamical mixing arguments or imprecise age measurements of stars associated with debris structures. Here, …
Modeling the 2012 May 17 Solar Energetic Particle Event Using the AWSoM and iPATH Models
Lario, D.; Li, Gang; de Nolfo, G. A. +6 more
We model the 2012 May 17 solar energetic particle event by combining the AWSoM and iPATH codes. Using this combined approach, we investigate particle acceleration when the parent coronal mass ejection (CME) is still close to the Sun. We have obtained reasonable agreements between our simulation and observations made by multiple spacecraft. We foll…
Source Counts Spanning Eight Decades of Flux Density at 1.4 GHz
Mauch, T.; Condon, J. J.; Cotton, W. D. +1 more
Brightness-weighted differential source counts S2n(S) spanning the eight decades of flux density between 0.25 µJy and 25 Jy at 1.4 GHz were measured from (1) the confusion brightness distribution in the MeerKAT DEEP2 image below 10 µJy, (2) counts of DEEP2 sources between 10 µJy and 2.5 mJy, and (3) counts of NVSS sour…
Thermal and Turbulent Properties of the Warm Neutral Medium in the Solar Neighborhood
Miville-Deschênes, Marc-Antoine; Marchal, Antoine
The transition from the diffuse warm neutral medium (WNM) to the dense cold neutral medium (CNM) is what set the initial conditions to the formation of molecular clouds. The properties of the turbulent cascade in the WNM, essential to describe this radiative condensation process, have remained elusive in part due to the difficulty in mapping out t…
Cepheids with Giant Companions. I. Revealing a Numerous Population of Double-lined Binary Cepheids
Anderson, Richard I.; Gieren, Wolfgang; Pietrzyński, Grzegorz +5 more
Masses of classical Cepheids of 3-11 M⊙ are predicted by theory but those measured clump between 3.6-5 M⊙. As a result, their mass-luminosity relation is poorly constrained, impeding our understanding of basic stellar physics and the Leavitt Law. All Cepheid masses come from the analysis of 11 binary systems, including only f…
The Carnegie Chicago Hubble Program X: Tip of the Red Giant Branch Distances to NGC 5643 and NGC 1404
Madore, Barry F.; Freedman, Wendy L.; Beaton, Rachael L. +7 more
The primary goal of the Carnegie Chicago Hubble Program (CCHP) is to calibrate the zero-point of the Type Ia supernova (SN Ia) Hubble Diagram through the use of Population II standard candles. So far, the CCHP has measured direct distances to 11 SNe Ia, and here we increase that number to 15 with two new Tip of the Red Giant Branch (TRGB) distance…
Investigating the Relative Gas and Small Dust Grain Surface Heights in Protoplanetary Disks
Monnier, John D.; Adams, Fred C.; Teague, Richard +7 more
Dust evolution in protoplanetary disks from small dust grains to pebbles is key to the planet formation process. The gas in protoplanetary disks should influence the vertical distribution of small dust grains (∼1 µm) in the disk. Utilizing archival near-infrared polarized light and millimeter observations, we can measure the scale height and…