Search Publications
A Detection of Gas Associated with the M31 Stellar Stream
Danforth, Charles W.; Rich, R. Michael; Keeney, Brian A. +2 more
Detailed studies of stellar populations in the halos of the Milky Way and the Andromeda (M31) galaxies have shown increasing numbers of tidal streams and dwarf galaxies, attesting to a complicated and on-going process of hierarchical structure formation. The most prominent feature in the halo of M31 is the Giant Stellar Stream, a structure ∼4.°5 i…
A Luminous X-Ray Flare from the Nucleus of the Dormant Bulgeless Spiral Galaxy NGC 247
Tao, Lian; Feng, Hua; Grisé, Fabien +4 more
NGC 247 is a nearby late-type bulgeless spiral galaxy that contains an inactive nucleus. We report a serendipitous discovery of an X-ray flare from the galaxy center with a luminosity of up to 2× {10}39 erg s-1 in the 0.3-10 keV band with XMM-Newton. A Chandra observation confirms that the new X-ray source is spatially coinci…
When did Round Disk Galaxies Form?
Ohta, K.; Yabe, K.; Takeuchi, T. M. +1 more
When and how galaxy morphology, such as the disk and bulge seen in the present-day universe, emerged is still not clear. In the universe at z >~ 2, galaxies with various morphologies are seen, and star-forming galaxies at z ~ 2 show the intrinsic shape of bar-like structures. Then, when did the round disk structure form? Here we take a simple a…
The Odd Offset between the Galactic Disk and Its Bar in NGC~3906
Ho, Luis C.; Erroz-Ferrer, Santiago; Schinnerer, Eva +27 more
We use mid-infrared 3.6 and 4.5 µm imaging of NGC 3906 from the Spitzer Survey of Stellar Structure in Galaxies (S4G) to understand the nature of an unusual offset between its stellar bar and the photometric center of an otherwise regular, circular outer stellar disk. We measure an offset of ∼910 pc between the center of the stell…
Comparative Morphology of Solar Relativistic Particle Events
Valtonen, Eino; Kocharov, Leon; Ryan, James M. +2 more
Time profiles of the 0.25-10 MeV electrons and the ∼(0.1-1) GeV nucleon-1 protons and helium associated with two solar coronal mass ejections (CMEs) are analyzed with a newly formulated method based on modeling of the particle transport in the interplanetary medium. With the modeling, we fit the observed angular distribution of solar pa…
Spectroscopic Infrared Extinction Mapping as a Probe of Grain Growth in IRDCs
Tan, Jonathan C.; Lim, Wanggi; Carey, Sean J.
We present spectroscopic tests of MIR to FIR extinction laws in IRDC G028.36+00.07, a potential site of massive star and star cluster formation. Lim & Tan developed methods of FIR extinction mapping of this source using Spitzer-MIPS 24 µm and Herschel-PACS 70 µm images, and by comparing to MIR Spitzer-IRAC 3-8 µm extinction m…
Dust Heating By Low-mass Stars in Massive Galaxies at z< 1
Taniguchi, Y.; Kajisawa, M.; Ichikawa, T. +3 more
Using the Hubble Space Telescope/Wide Field Camera 3 imaging data and multi-wavelength photometric catalog, we investigated the dust temperature of passively evolving and star-forming galaxies at 0.2\lt z\lt 1.0 in the CANDELS fields. We estimated the stellar radiation field by low-mass stars from the stellar mass and surface brightness profile of…
X-ray Emission from Stellar Jets by Collision against High-density Molecular Clouds: an Application to HH 248
Miceli, M.; Orlando, S.; Bonito, R. +6 more
We investigate the plausibility of detecting X-ray emission from a stellar jet that impacts a dense molecular cloud, a scenario that may be typical for classical T Tauri stars with jets in dense star-forming complexes. We first model the impact of a jet against a dense cloud using two-dimensional axisymmetric hydrodynamic simulations, exploring di…
The Hyperfine Structure of the Rotational Spectrum of HDO and its Extension to the THz Region: Accurate Rest Frequencies and Spectroscopic Parameters Forastrophysical Observations
Puzzarini, Cristina; Lattanzi, Valerio; Cazzoli, Gabriele +2 more
The rotational spectrum of the mono-deuterated isotopologue of water, HD16O, has been investigated in the millimeter- and submillimeter-wave frequency regions, up to 1.6 THz. The Lamb-dip technique has been exploited to obtain sub-Doppler resolution and to resolve the hyperfine (hf) structure due to the deuterium and hydrogen nuclei, th…
Extended, Dusty Star Formation Fueled by a Residual Cooling Flow in the Cluster of Galaxies Sérsic 159-03
Veilleux, S.; McDonald, M.; Werner, N. +1 more
While the cooling of the hot intracluster medium (ICM) in the cores of galaxy clusters is mostly counteracted by heating from the central active galactic nucleus (AGN), the balance is not perfect. This can lead to residual cooling flows and low-level star formation, the physics of which is not well understood. Here we present a detailed study of t…