scholarly journals Si and Fe Depletion in Galactic Star‐forming Regions Observed by theSpitzer Space Telescope

2008 ◽  
Vol 682 (1) ◽  
pp. 416-433 ◽  
Author(s):  
Yoko Okada ◽  
Takashi Onaka ◽  
Takashi Miyata ◽  
Yoshiko K. Okamoto ◽  
Itsuki Sakon ◽  
...  
2001 ◽  
Vol 121 (1) ◽  
pp. 182-197 ◽  
Author(s):  
Debra Meloy Elmegreen ◽  
Michele Kaufman ◽  
Bruce G. Elmegreen ◽  
Elias Brinks ◽  
Curtis Struck ◽  
...  

2019 ◽  
Vol 486 (3) ◽  
pp. 3350-3367 ◽  
Author(s):  
Dinalva A Sales ◽  
A Robinson ◽  
R A Riffel ◽  
T Storchi-Bergmann ◽  
J F Gallimore ◽  
...  

AbstractWe present a multiwavelength study of the OH megamaser galaxy IRAS17526 + 3253, based on new Gemini multi-object spectrograph integral field unit (GMOS/IFU) observations, Hubble Space Telescope F814W, and H α + [N ii] images, and archival 2MASS and 1.49 GHz VLA data. The Hubble Space Telescope(HST) images clearly reveal a mid-to-advanced stage major merger whose northwestern and southeastern nuclei have a projected separation of ∼8.5 kpc. Our HST/H α + [N ii] image shows regions of ongoing star formation across the envelope on ∼10 kpc scales, which are aligned with radio features, supporting the interpretation that the radio emission originates from star-forming regions. The measured H α luminosities imply that the unobscured star formation rate (SFR) is ∼10–30 M⊙ yr−1. The GMOS/IFU data reveal two structures in northwestern separated by 850 pc and by a discontinuity in the velocity field of ∼ 200 km s−1. We associate the blueshifted and redshifted components with, respectively, the distorted disc of northwestern and tidal debris, possibly a tail originating in southeastern. Star formation is the main ionization source in both components, which have SFRs of ∼2.6–7.9 M⊙ yr−1 and ∼1.5–4.5 M⊙ yr−1, respectively. Fainter line emission bordering these main components is consistent with shock ionization at a velocity ∼200 km s−1 and may be the result of an interaction between the tidal tail and the northwestern galaxy’s disc. IRAS17526 + 3253 is one of only a few systems known to host both luminous OH and H2O masers. The velocities of the OH and H2O maser lines suggest that they are associated with the northwestern and southeastern galaxies, respectively (Martin et al.; Wagner).


1998 ◽  
Vol 116 (6) ◽  
pp. 2953-2964 ◽  
Author(s):  
Guillem Anglada ◽  
Eva Villuendas ◽  
Robert Estalella ◽  
Maria T. Beltrán ◽  
Luis F. Rodríguez ◽  
...  

1998 ◽  
Vol 11 (1) ◽  
pp. 423-424
Author(s):  
Motohide Tamura ◽  
Yoichi Itoh ◽  
Yumiko Oasa ◽  
Alan Tokunaga ◽  
Koji Sugitani

Abstract In order to tackle the problems of low-mass end of the initial mass function (IMF) in star-forming regions and the formation mechanisms of brown dwarfs, we have conducted deep infrared surveys of nearby molecular clouds. We have found a significant population of very low-luminosity sources with IR excesses in the Taurus cloud and the Chamaeleon cloud core regions whose extinction corrected J magnitudes are 3 to 8 mag fainter than those of typical T Tauri stars in the same cloud. Some of them are associated with even fainter companions. Follow-up IR spectroscopy has confirmed for the selected sources that their photospheric temperature is around 2000 to 3000 K. Thus, these very low-luminosity young stellar sources are most likely very low-mass T Tauri stars, and some of them might even be young brown dwarfs.


2020 ◽  
Vol 501 (1) ◽  
pp. L12-L17
Author(s):  
Christina Schoettler ◽  
Richard J Parker

ABSTRACT Planetary systems appear to form contemporaneously around young stars within young star-forming regions. Within these environments, the chances of survival, as well as the long-term evolution of these systems, are influenced by factors such as dynamical interactions with other stars and photoevaporation from massive stars. These interactions can also cause young stars to be ejected from their birth regions and become runaways. We present examples of such runaway stars in the vicinity of the Orion Nebula Cluster (ONC) found in Gaia DR2 data that have retained their discs during the ejection process. Once set on their path, these runaways usually do not encounter any other dense regions that could endanger the survival of their discs or young planetary systems. However, we show that it is possible for star–disc systems, presumably ejected from one dense star-forming region, to encounter a second dense region, in our case the ONC. While the interactions of the ejected star–disc systems in the second region are unlikely to be the same as in their birth region, a second encounter will increase the risk to the disc or planetary system from malign external effects.


Author(s):  
Kosuke Fujii ◽  
Norikazu Mizuno ◽  
J R Dawson ◽  
Tsuyoshi Inoue ◽  
Kazufumi Torii ◽  
...  

Abstract We investigate the H i envelope of the young, massive GMCs in the star-forming regions N48 and N49, which are located within the high column density H i ridge between two kpc-scale supergiant shells, LMC 4 and LMC 5. New long-baseline H i 21 cm line observations with the Australia Telescope Compact Array (ATCA) were combined with archival shorter baseline data and single dish data from the Parkes telescope, for a final synthesized beam size of 24.75″ by 20.48″, which corresponds to a spatial resolution of ∼ 6 pc in the LMC. It is newly revealed that the H i gas is highly filamentary, and that the molecular clumps are distributed along filamentary H i features. In total 39 filamentary features are identified and their typical width is ∼ 21 (8–49) [pc]. We propose a scenario in which the GMCs were formed via gravitational instabilities in atomic gas which was initially accumulated by the two shells and then further compressed by their collision. This suggests that GMC formation involves the filamentary nature of the atomic medium.


2020 ◽  
Vol 15 (S359) ◽  
pp. 347-349
Author(s):  
Carpes P. Hekatelyne ◽  
Thaisa Storchi-Bergmann

AbstractWe present Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Hubble Space Telescope (HST) and Very Large Array (VLA) observations of the inner kpc of the OH Megamaser galaxy IRAS 11506-3851. In this work we discuss the kinematics and excitation of the gas as well as its radio emission. The HST images reveal an isolated spiral galaxy and the combination with the GMOS-IFU flux distributions allowed us to identify a partial ring of star-forming regions surrounding the nucleus with a radius of ≍500 pc. The emission-line ratios and excitation map reveal that the region inside the ring present mixed/transition excitation between those of Starbursts and Active Galactic Nuclei (AGN), while regions along the ring are excited by Starbursts. We suggest that we are probing a buried or fading AGN that could be both exciting the gas and originating an outflow.


2015 ◽  
Vol 806 (1) ◽  
pp. L17 ◽  
Author(s):  
A. M. Swinbank ◽  
S. Dye ◽  
J. W. Nightingale ◽  
C. Furlanetto ◽  
Ian Smail ◽  
...  

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