Search Publications
M17 MIR: A Massive Protostar with Multiple Accretion Outbursts
Chen, Zhiwei; Chen, Xuepeng; Haas, Martin +3 more
We report the discovery of a massive protostar M17 MIR embedded in a hot molecular core in M17. The multiwavelength data obtained during 1993-2019 show significant mid-IR (MIR) variations, which can be split into three stages: the decreasing phase during 1993.03-mid-2004, the quiescent phase from mid-2004 to mid-2010, and the rebrightening phase f…
Millimeter-sized Dust Grains Surviving the Water-sublimating Temperature in the Inner 10 au of the FU Ori Disk
Chen, Wen Ping; Liu, Sheng-Yuan; Takami, Michihiro +11 more
Previous observations have shown that the ≲10 au, ≳400 K hot inner disk of the archetypal accretion outburst young stellar object, FU Ori, is dominated by viscous heating. To constrain dust properties in this region, we have performed radio observations toward this disk using the Karl G. Jansky Very Large Array in 2020 June-July, September, and No…
Hinode/EIS Coronal Magnetic Field Measurements at the Onset of a C2 Flare
Landi, E.; Li, W.; Hutton, R. +1 more
We study Hinode/EIS observations of an active region taken before, during, and after a small C2.0 flare in order to monitor the evolution of the magnetic field and its relation to the flare event. We find that while the flare left the active region itself unaltered, the event included a large magnetic field enhancement (MFE), which consisted of a …
Global Distribution of the Solar Wind Speed Reconstructed from Improved Tomographic Analysis of Interplanetary Scintillation Observations between 1985 and 2019
Kojima, Masayoshi; Tokumaru, Munetoshi; Fujiki, Ken'ichi +1 more
Computer-assisted tomography (CAT) for interplanetary scintillation (IPS) observations enables the determination of the global distribution of solar wind speed. We compared solar wind speeds derived from the CAT analysis of IPS observations between 1985 and 2019 with in situ observations conducted by the near-Earth and Ulysses spacecraft. From thi…
Spectroscopy and Photometry of the Least Massive Type II Globular Clusters: NGC 1261 and NGC 6934
Da Costa, G. S.; Milone, A. P.; Cordoni, G. +10 more
Recent work has revealed two classes of globular clusters (GCs), dubbed Type I and Type II. Type II GCs are characterized by both a blue and a red red giant branch composed of stars with different metallicities, often coupled with distinct abundances in the slow neutron-capture elements (s-elements). Here we continue the chemical tagging of Type I…
Resolving the Dust-to-Metals Ratio and CO-to-H2 Conversion Factor in the Nearby Universe
Sandstrom, Karin M.; Leroy, Adam K.; Schruba, Andreas +8 more
We investigate the relationship between the dust-to-metals ratio (D/M) and the local interstellar medium environment at ∼2 kpc resolution in five nearby galaxies: IC 342, M31, M33, M101, and NGC 628. A modified blackbody model with a broken power-law emissivity is used to model the dust emission from 100 to 500 µm observed by Herschel. We ut…
Grain Growth in Escaping Atmospheres: Implications for the Radius Inflation of Super-Puffs
Ohno, Kazumasa; Tanaka, Yuki A.
Super-puffs-low-mass exoplanets with extremely low bulk density-are attractive targets for exploring their atmospheres and formation processes. Recent studies suggested that the large radii of super-puffs may be caused by atmospheric dust entrained in the escaping atmospheres. In this study, we investigate how the dust grows in escaping atmosphere…
Head-to-Toe Measurement of El Gordo: Improved Analysis of the Galaxy Cluster ACT-CL J0102-4915 with New Wide-field Hubble Space Telescope Imaging Data
Sifón, Cristóbal; Hughes, John P.; Jee, M. James +6 more
We present an improved weak-lensing (WL) study of the high-z (z = 0.87) merging galaxy cluster ACT-CL J0102-4915 ("El Gordo") based on new wide-field Hubble Space Telescope imaging data. The new imaging data cover the ~3.5 × ~3.5 Mpc region centered on the cluster and enable us to detect WL signals beyond the virial radius, which was not possible …
Revisiting Dynamical Friction: The Role of Global Modes and Local Wakes
Babul, Arif; Quinn, Thomas R.; Mayer, Lucio +4 more
The orbital decay of a perturber within a larger system plays a key role in the dynamics of many astrophysical systems-from nuclear star clusters or globular clusters in galaxies, to massive black holes in galactic nuclei, to dwarf galaxy satellites within the dark matter halos of more massive galaxies. For many decades, there have been various at…
R-process-rich Stellar Streams in the Milky Way
Roederer, Ian U.; Frebel, Anna; Ji, Alexander P. +3 more
We present high-resolution Magellan/MIKE spectra of 22 bright (9 < V < 13.5) metal-poor stars (-3.18 < [Fe/H] < -1.37) in three different stellar streams, the Helmi debris stream, the Helmi trail stream, and the ω Centauri progenitor stream. We augment our Helmi debris sample with results for 10 stars by Roederer et al. for a total of …