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On the Co-orbitation of Satellite Galaxies along the Great Plane of Andromeda: NGC 147, NGC 185, and Expectations from Cosmological Simulations
Pawlowski, Marcel S.; Tony Sohn, Sangmo
Half of the satellite galaxies of Andromeda form a narrow plane termed the Great Plane of Andromeda (GPoA), and their line-of-sight velocities display a correlation reminiscent of a rotating structure. Recently reported first proper-motion measurements for the on-plane satellites NGC 147 and NGC 185 indicate that they indeed co-orbit along the GPo…
The Dusty Heart of NGC 4151 Revealed by λ ∼ 1-40 µm Reverberation Mapping and Variability: A Challenge to Current Clumpy Torus Models
Lyu, Jianwei; Rieke, George H.
We probe the dusty environment of the archetypical Type 1 active galactic nucleus (AGN) in NGC 4151 with comprehensive IR reverberation mapping over several decades, in the J (∼1.22 µm), H (∼1.63 µm), K (∼2.19 µm), L (∼3.45 µm), and N bands (∼10.6 µm), plus multiple measurements at 20-40 µm. At 1-4 µm, the…
Orbital Torus Imaging: Using Element Abundances to Map Orbits and Mass in the Milky Way
Brownstein, Joel R.; Hogg, David W.; Rix, Hans-Walter +11 more
Many approaches to galaxy dynamics assume that the gravitational potential is simple and the distribution function is time invariant. Under these assumptions there are traditional tools for inferring potential parameters given observations of stellar kinematics (e.g., Jeans models). However, spectroscopic surveys measure many stellar properties be…
Correction to the Photometric Colors of Gaia Early Data Release 3
Niu, Zexi; Liu, Jifeng; Yuan, Haibo
In this work, we use the spectroscopy-based stellar color regression method with ∼0.7 million common stars between LAMOST DR7 and Gaia EDR3 to acquire color corrections in G - GRP and GBP - GRP. A sub-millimagnitude precision is achieved. Our results demonstrate that improvements in the calibration process of the E…
Spiral Arm Pattern Motion in the SAO 206462 Protoplanetary Disk
Dong, Ruobing; Pueyo, Laurent; Stolker, Tomas +5 more
Spiral arms have been observed in more than a dozen protoplanetary disks, yet the origin of nearly all systems is under debate. Multi-epoch monitoring of spiral arm morphology offers a dynamical way to distinguish two leading arm formation mechanisms: companion-driven and gravitational instability induction, since these mechanisms predict distinct…
Highly r-process enhanced stars in ultra-faint dwarf galaxies
Bromm, Volker; Besla, Gurtina; Jeon, Myoungwon
Highly r-process enhanced metal-poor stars (MP r-II; $\rm [Eu/Fe]\gt 1$ and $\rm [Fe/H]\lesssim -1.5$) have been observed in ultra-faint dwarf (UFD) galaxy, specifically in Reticulum II (Ret II). The fact that only a few UFDs contain such stars implies that the r-process site may reflect very rare but individually prolific events, such as neutron …
Multiple Stellar Populations in Asymptotic Giant Branch Stars of Galactic Globular Clusters
Milone, A. P.; Cordoni, G.; Marino, A. F. +8 more
Multiple stellar populations (MPs) are a distinct characteristic of globular clusters (GCs). Their general properties have been widely studied among main-sequence, red giant branch (RGB), and horizontal branch (HB) stars, but a common framework is still missing at later evolutionary stages. We studied the MP phenomenon along the asymptotic giant b…
The Late-time Radio Behavior of Gamma-ray Burst Afterglows: Testing the Standard Model
Fruchter, Andrew S.; Kangas, Tuomas
We examine a sample of 21 gamma-ray burst (GRB) afterglow light curves at radio frequencies and compare them to the X-ray and/or optical properties of the afterglows and to the predictions of the standard jet/fireball model. Our sample includes every Swift GRB with an X-ray light curve indicating a jet break and with a published radio light curve,…
A Near-infrared Survey of UV-excited Molecular Hydrogen in Photodissociation Regions
Kim, Hwihyun; Dinerstein, Harriet L.; Jaffe, Daniel T. +1 more
We present a comparative study of the near-infrared (NIR) H2 line emission from five regions near hot young stars: Sharpless 140, NGC 2023, IC 63, the Horsehead Nebula, and the Orion Bar. This emission originates in photodissociation or photon-dominated regions (PDRs), interfaces between photoionized and molecular gas near hot (O) stars…
The Be Star 66 Ophiuchi: 60 Years of Disk Evolution
Carciofi, A. C.; Mota, B. C.; Jones, C. E. +5 more
We use a time-dependent hydrodynamic code and a non-LTE Monte Carlo code to model disk dissipation for the Be star 66 Ophiuchi. We compiled 63 years of observations from 1957 to 2020 to encompass the complete history of the growth and subsequent dissipation of the star's disk. Our models are constrained by new and archival photometry, spectroscopy…