VLA Search for Optically Thick H II Regions in Luminous Embedded Infrared Sources

1987 ◽  
pp. 185-186
Author(s):  
Paul T. P. Ho ◽  
T. N. Rengarajan
Keyword(s):  
H Ii Regions ◽  
Infrared Sources

Compact Infrared Sources Associated with Southern H II Regions

1974 ◽  
Vol 192 ◽  
pp. 351 ◽  
Author(s):  
Jay A. Frogel ◽  
S. Eric Persson
Keyword(s):  
H Ii Regions ◽  
Infrared Sources

scholarly journals POLARIMETRY OF INFRARED SOURCES

1981 ◽  
Vol 96 ◽  
pp. 223-236 ◽  
Author(s):  
H. M. Dyck ◽  
Carol J. Lonsdale
Keyword(s):  
Molecular Clouds ◽  
H Ii Regions ◽  
Small Particles ◽  
Stellar Radiation ◽  
Cool Stars ◽  
The Galaxy ◽  
Circumstellar Shells ◽  
Infrared Wavelengths ◽  
Stellar Sources ◽  
Infrared Sources

Polarization at infrared wavelengths has been detected from a number of different objects within the Galaxy. These include young sources associated with molecular clouds and H II regions, cool stars with thick circumstellar shells, bi-polar nebulae, and normal stars suffering interstellar polarization. Typical levels of polarization detected at 2.2 μm are up to 25% for the molecular cloud sources, less than −5% for the cool stars, around 30% for some bi-polar nebulae and less than −2% for interstellar polarization. For the latter three types of source the origin of the polarization is basically understood: it results from scattering of stellar radiation off small particles in the surrounding shell or nebula in the cool stars and bi-polar nebulae and by transfer of flux through a foreground medium of aligned dust grains for the interstellar polarization. The phenomenon of large infrared polarization in the young stellar and pre-stellar sources is less well understood, and it is to this problem that we address ourselves in this review.

scholarly journals Observing the influence of the youngest super star clusters in NGC 1569: Keck Brackett α spectroscopy

2021 ◽  
Vol 503 (2) ◽  
pp. 2187-2194
Author(s):  
Daniel P Cohen ◽  
Jean L Turner ◽  
Sara C Beck ◽  
S Michelle Consiglio
Keyword(s):  
Near Infrared ◽  
Star Clusters ◽  
Radio Continuum ◽  
H Ii Regions ◽  
Infrared Source ◽  
H Ii Region ◽  
Super Star Clusters ◽  
Infrared Sources ◽  
Massive Clusters ◽  
Ngc 1569

ABSTRACT We report Keck–NIRSPEC observations of the Brackett α 4.05 μm recombination line across the two candidate embedded super star clusters (SSCs) in NGC 1569. These SSCs power a bright H ii region and have been previously detected as radio and mid-infrared sources. Supplemented with high-resolution VLA mapping of the radio continuum along with IRTF–TEXES spectroscopy of the [S iv] 10.5 μm line, the Brackett α data provide new insight into the dynamical state of gas ionized by these forming massive clusters. Near-infrared sources detected in 2 μm images from the slit-viewing Camera are matched with Gaia sources to obtain accurate celestial coordinates and slit positions to within ∼0${_{.}^{\prime\prime}}$1. Br α is detected as a strong emission peak powered by the less luminous infrared source, MIR1 (LIR ∼ 2 × 107 $\rm L_\odot$). The second candidate SSC MIR2 is more luminous (LIR ≳ 4 × 108 $\rm L_\odot$) but exhibits weak radio continuum and Br α emission, suggesting the ionized gas is extremely dense (ne ≳ 105 cm−3), corresponding to hypercompact H ii regions around newborn massive stars. The Br α and [S iv] lines across the region are both remarkably symmetric and extremely narrow, with observed line widths Δv ≃ 40 $\rm km\, s^{-1}$, full width at half-maximum. This result is the first clear evidence that feedback from NGC 1569’s youngest giant clusters is currently incapable of rapid gas dispersal, consistent with the emerging theoretical paradigm in the formation of giant star clusters.

scholarly journals Young Stars in the Camelopardalis Dust and Molecular Clouds. VI. YSOs Verified by Spitzer and Akari Infrared Photometry

2010 ◽  
Vol 19 (1-2) ◽  
pp. 1-33
Author(s):  
V. Straižys ◽  
A. Kazlauskas
Keyword(s):  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
H Ii Regions ◽  
Infrared Photometry ◽  
Class Iii ◽  
Star Forming ◽  
Star Forming Regions ◽  
Dusty Galaxies ◽  
Infrared Surveys ◽  
Infrared Sources

AbstractUsing photometric data of infrared surveys, young stellar object (YSO) status is verified for 141 objects selected in our previous papers in the Cassiopeia and Camelopardalis segment of the Milky Way bounded by Galactic coordinates (l, b) = (132-158°, ±12°). The area includes the known star- forming regions in the emission nebulae W3, W4 and W5 and the massive YSO AFGL490. Spectral energy distribution (SED) curves between 700 nm and 160 μm, constructed from the GSC 2, 2MASS, IRAS, MSX, Spitzer and AKARI data, are used to estimate the evolutionary stages of these stars. We confirm the YSO status for most of the objects. If all of the investigated objects were YSOs, 45% of them should belong to Class I, 41% to class II and 14% to Class III. However, SEDs of some of these objects can be affected by nearby extended infrared sources, like compact H II regions, infrared clusters or dusty galaxies.

scholarly journals VLA Search for Optically Thick H II Regions in Luminous Embedded Infrared Sources

1987 ◽  
Vol 115 ◽  
pp. 185-186
Author(s):  
Paul T.P. Ho ◽  
T. N. Rengarajan
Keyword(s):  
High Resolution ◽  
Radio Emission ◽  
High Sensitivity ◽  
Radio Continuum ◽  
Continuum Emission ◽  
H Ii Regions ◽  
Upper Limit ◽  
Infrared Sources ◽  
Sensitivity Maps

We have searched for radio continuum emission at 15 GHz from a number of deeply embedded protostar like infrared objects, using the B configuration of the VLA. The aim was to get high resolution (1″) and high sensitivity maps. For 10 objects (NGC 7538-IRS 3, GL 989, GL 4029-IRS 1, GL 437N, GL 2789, NGC 1333-IRS 13, S235B, GL 4029-IRS 2, R Mon and OMC2-IRS 3) we did not detect radio emission, the 3 upper limit being 0.3 – 0.5 mJy. Positive detections were made for W33A, 0MC2-IRS 4, S 235-IRS 1 and NGC 6334V-IRS 4. The cleaned maps for these objects are shown in Figures 1-4.

scholarly journals New Infrared Sources Associated with H II Regions

1973 ◽  
Vol 52 ◽  
pp. 459-463
Author(s):  
C. G. Wynn-Williams ◽  
E. E. Becklin ◽  
G. Neugebauer
Keyword(s):  
Wavelength Range ◽  
Infrared Emission ◽  
Emission Sources ◽  
H Ii Regions ◽  
Spatial Relationships ◽  
Ionized Gas ◽  
Infrared Sources ◽  
Free Spectra

Photometry and mapping in the wavelength range 1.65–20 μ of the H II regions W3 and NGC 7538 have led to the discovery of a dozen new infrared emission sources. The sources have flux densities ranging up to 10–23 Wm–2 Hz–1 at 20 μ and diameters from < 3 to 40″. Some are associated with, and have similar brightness distributions to compact H II condensations observed at radio wavelengths; they have, however, 20-μ flux densities much greater than, and 2-μ flux densities much less than are predicted from the radio free-free spectra. It is concluded that in many cases there exist close spatial relationships between the hot dust and the ionized gas, and between infrared and OH/H2O emission sources.

New Infrared Sources Associated with H ii Regions

1973 ◽  
pp. 459-463 ◽  
Author(s):  
C. G. Wynn-Williams ◽  
E. E. Becklin ◽  
G. Neugebauer
Keyword(s):  
H Ii Regions ◽  
Infrared Sources

scholarly journals Clumpy Structure in the W3 Molecular Core

1987 ◽  
Vol 115 ◽  
pp. 163-166
Author(s):  
Hideyuki Kobayashi ◽  
Masahiko Hayashi ◽  
Tetsuo Hasegawa
Keyword(s):  
Angular Resolution ◽  
Young Star ◽  
High Angular Resolution ◽  
H Ii Regions ◽  
Molecular Line ◽  
The Core ◽  
Molecular Core ◽  
Resolution Observation ◽  
Infrared Sources ◽  
Co Emission

The core region of the W3 molecular cloud has high molecular line luminosities (Dickel et al. 1980; Brackman and Scoville 1980). This region contains luminous infrared sources and ultra compact H II regions. A young star cluster may be forming in this region. Recent interferometric high angular-resolution observation revealed a bipolar outflow toward IRS 5 in the CO emission (Claussen et al. 1984) and a mass condensation in the HCN emission (Wright et al. 1984) in this region.

Sign in / Sign up

Export Citation Format

Share Document