Search Publications
First Observational Signature of Rotational Deceleration in a Massive, Intermediate-age Star Cluster in the Magellanic Clouds
Deng, Licai; de Grijs, Richard; Li, Chengyuan +1 more
While the extended main-sequence turnoffs (eMSTOs) found in almost all 1-2 Gyr old star clusters in the Magellanic Clouds are often explained by postulating extended star formation histories (SFHs), the tight subgiant branches (SGBs) seen in some clusters challenge this popular scenario. Puzzlingly, the SGB of the eMSTO cluster NGC 419 is signific…
The X-Ray Luminosity Function of M37 and the Evolution of Coronal Activity in Low-mass Stars
Agüeros, Marcel A.; Núñez, Alejandro
We use a 440.5 ks Chandra observation of the ≈500 Myr old open cluster M37 to derive the X-ray luminosity functions of its ≤1.2 {M}⊙ stars. Combining detections of 162 M37 members with upper limits for 160 non-detections, we find that its G, K, and M stars have a similar median (0.5-7 keV) X-ray luminosity {L}{{X}}={10}…
Validation of the Coronal Thick Target Source Model
Xu, Yan; Fleishman, Gregory D.; Gary, Dale E. +1 more
We present detailed 3D modeling of a dense, coronal thick-target X-ray flare using the GX Simulator tool, photospheric magnetic measurements, and microwave imaging and spectroscopy data. The developed model offers a remarkable agreement between the synthesized and observed spectra and images in both X-ray and microwave domains, which validates the…
The Fate of a Red Nugget: In Situ Star Formation of Satellites around a Massive Compact Galaxy
Morishita, Takahiro; Ichikawa, Takashi
To study the accretion phase for local massive galaxies, we search accreting satellites around a massive compact galaxy ({M}*∼ 3.9× {10}10{M}⊙ ), spectroscopically confirmed ({z}{{spec}}=1.9213) in the eXtreme Deep Field, which has been originally reported in Szomoru et al. We detect 1369 satellite candi…
Coronal Magnetic Fields Derived from Simultaneous Microwave and EUV Observations and Comparison with the Potential Field Model
Shibasaki, Kiyoto; Shiota, Daikou; Nozawa, Satoshi +2 more
We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and the differential emission measure measurements using EUV observations. We derived line-of-sight components of the coronal magnetic field from polarization observations of the thermal bremsstrahlung in the NOAA …
A New Challenge to Solar Dynamo Models from Helioseismic Observations: The Latitudinal Dependence of the Progression of the Solar Cycle
Hill, F.; Jain, K.; Tripathy, S. C. +1 more
The onset of the solar cycle at mid-latitudes, the slowdown in the drift of sunspots toward the equator, the tail-like attachment, and the overlap of successive cycles at the time of minimum activity are delicate issues in models of the αΩ dynamo wave and the flux transport dynamo. Very different parameter values produce similar results, making it…
A Search for O2 in CO-depleted Molecular Cloud Cores with Herschel
Ceccarelli, Cecilia; Charnley, Steven B.; Cordiner, Martin A. +1 more
The general lack of molecular oxygen in molecular clouds is an outstanding problem in astrochemistry. Extensive searches with the Submillimeter Astronomical Satellite, Odin, and Herschel have only produced two detections; upper limits to the O2 abundance in the remaining sources observed are about 1000 times lower than predicted by chem…
Radial Distribution of ISM Gas-phase Metallicity in CLASH Clusters at z ~ 0.35: A New Outlook on Environmental Impact on Galaxy Evolution
Kewley, Lisa J.; Tran, Kim-Vy H.; Gupta, Anshu +3 more
We present the first observation of cluster-scale radial metallicity gradients from star-forming galaxies. We use DEIMOS on the Keck II telescope to observe two CLASH clusters at z ∼ 0.35: MACS J1115+0129 and RX J1532+3021. Based on our measured interstellar medium properties of star-forming galaxies out to a radius of 2.5 Mpc from the cluster cen…
The 6 µm Feature As a Tracer of Aliphatic Components of Interstellar Carbonaceous Grains
Zhang, Yong; Kwok, Sun; Hsia, Chih-Hao +1 more
An unidentified infrared emission (UIE) feature at 6.0 µm is detected in a number of astronomical sources showing the UIE bands. In contrast to the previous suggestion that this band is due to C=O vibrational modes, we suggest that the 6.0 µm feature arises from olefinic double-bond functional groups. These groups are likely to be atta…
The Circumgalactic Medium of Submillimeter Galaxies. I. First Results from a Radio-identified Sample
Cooray, A.; Fu, Hai; Michałowski, M. J. +14 more
We present the first results from an ongoing survey to characterize the circumgalactic medium (CGM) of massive high-redshift galaxies detected as submillimeter galaxies (SMGs). We constructed a parent sample of 163 SMG-QSO pairs with separations less than ∼36″ by cross-matching far-infrared-selected galaxies from Herschel with spectroscopically co…