Search Publications
Early Stages of Cluster Formation: Fragmentation of Massive Dense Cores down to <~ 1000 AU
Fuente, Asunción; Zhang, Qizhou; Palau, Aina +11 more
In order to study the fragmentation of massive dense cores, which constitute the cluster cradles, we observed the continuum at 1.3 mm and the CO (2-1) emission of four massive cores with the Plateau de Bure Interferometer in the most extended configuration. We detected dust condensations down to ~0.3 M ⊙ and separate millimeter sources …
A Binary Progenitor for the Type IIb Supernova 2011dh in M51
Nomoto, Ken'ichi; Bersten, Melina C.; Benvenuto, Omar G.
We perform binary stellar evolutionary calculations following the simultaneous evolution of both stars in the system to study a potential progenitor system for the Type IIb supernova 2011dh. Pre-explosion photometry as well as light-curve modeling has provided constraints on the physical properties of the progenitor system. Here, we present a clos…
Chandra X-Ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-scale Binary Active Galactic Nuclei. I. Nature of the Nuclear Ionizing Sources
Shen, Yue; Strauss, Michael A.; Greene, Jenny E. +3 more
Kiloparsec-scale binary active galactic nuclei (AGNs) signal active supermassive black hole (SMBH) pairs in merging galaxies. Despite their significance, unambiguously confirmed cases remain scarce and most have been discovered serendipitously. In a previous systematic search, we optically identified four kpc-scale binary AGNs from candidates sele…
Excited OH+, H2O+, and H3O+ in NGC 4418 and Arp 220
Lutz, D.; Genzel, R.; Poglitsch, A. +15 more
We report on Herschel/PACS observations of absorption lines of OH+, H2O+ and H3O+ in NGC 4418 and Arp 220. Excited lines of OH+ and H2O+ with Elower of at least 285 and ~200 K, respectively, are detected in both sources, indicating radiative pumping …
Shock-enhanced C+ Emission and the Detection of H2O from the Stephan's Quintet Group-wide Shock Using Herschel
Sturm, E.; Boulanger, F.; Falgarone, E. +20 more
We present the first Herschel spectroscopic detections of the [O I] 63 µm and [C II] 158 µm fine-structure transitions, and a single para-H2O line from the 35 × 15 kpc2 shocked intergalactic filament in Stephan's Quintet. The filament is believed to have been formed when a high-speed intruder to the group collided…
Massive starburst galaxies in a z = 2.16 proto-cluster unveiled by panoramic Hα mapping
Smail, Ian; Koyama, Yusei; Kodama, Tadayuki +5 more
We present a panoramic narrow-band study of Hα emitters in the field of the z = 2.16 proto-cluster around PKS 1138-262 using MOIRCS on the Subaru Telescope. We find 83 Hα emitters down to a star formation rate of SFR (Hα) ∼ 10 M⊙ yr-1 across a ∼ 7 × 7 arcmin2 region centred on the radio galaxy, and identify ∼10-Mpc…
A Dynamical Signature of Multiple Stellar Populations in 47 Tucanae
Anderson, Jay; Dotter, Aaron; Rich, R. Michael +5 more
Based on the width of its main sequence, and an actual observed split when viewed through particular filters, it is widely accepted that 47 Tucanae contains multiple stellar populations. In this contribution, we divide the main sequence of 47 Tuc into four color groups, which presumably represent stars of various chemical compositions. The kinemat…
The Collisional Evolution of Debris Disks
Rieke, George H.; Gáspár, András; Balog, Zoltán
We explore the collisional decay of disk mass and infrared emission in debris disks. With models, we show that the rate of the decay varies throughout the evolution of the disks, increasing its rate up to a certain point, which is followed by a leveling off to a slower value. The total disk mass falls off vpropt -0.35 at its fastest poi…
Transit Observations of the Hot Jupiter HD 189733b at X-Ray Wavelengths
Schmitt, J. H. M. M.; Poppenhaeger, K.; Wolk, S. J.
We present new X-ray observations obtained with Chandra ACIS-S of the HD 189733 system, consisting of a K-type star orbited by a transiting Hot Jupiter and an M-type stellar companion. We report a detection of the planetary transit in soft X-rays with a significantly deeper transit depth than observed in the optical. The X-ray data favor a transit…
Distance and Kinematics of the TW Hydrae Association from Parallaxes
Weinberger, Alycia J.; Anglada-Escudé, Guillem; Boss, Alan P.
From common proper motion and signatures of youth, researchers have identified about 30 members of a putative TW Hydrae Association. Only four of these had parallactic distances from Hipparcos. We have measured parallaxes and proper motions for 14 primary members. We combine these with literature values of radial velocities to show that the Galact…