A study of (C-13)O cloud cores in Ophiuchus

Nozawa, Satonori; Mizuno, Akira; Teshima, Yuji; Ogawa, Hideo; Fukui, Y.

doi:10.1086/191618

Cited by 56 publications

(109 citation statements)

References 0 publications

Supporting

Mentioning

101

Contrasting

Order By: Relevance

“…Therefore this value should be considered as an upper limit. In addition, the cloud is likely to be associated with the Ophiuchus complex at 160 ± 50 pc (Nozawa et al 1991), in agreement with the extinction upper limit of 160 ± 210 pc. For these reasons, we adopt a distance of 160 ± 50 pc with a reliability flag of 1.…”

Section: D1 G002+1802supporting

confidence: 84%

“…Therefore this value should be considered as an upper limit, but the very large value (4.33 kpc) does not provide a strong constraint. The cloud might be associated with the Ophiuchus complex at 160 ± 50 pc (Nozawa et al 1991), like G2.83+21.91 which is barely 1 degree westward. For want of better data, we adopt a distance of 160 ± 50 pc with a reliability flag of 0.…”

Section: D6 G372+2102mentioning

confidence: 95%

“…We note that with a galactic latitude of ∼22 degrees, such a great distance would correspond to a very large and unlikely galactic height. In addition, the cloud might be associated with the Ophiuchus complex at 160 ± 50 pc (Nozawa et al 1991), but this association requires a deeper investigation. For want of better data, we adopt a distance of 300 ± 300 pc with a reliability flag of 0.…”

Section: D4 G283+2191mentioning

confidence: 99%

“…Several references provide distance estimates that can be relevant for this cloud. The cloud might be associated with the Ophiuchus complex at 160 ± 50 pc (Nozawa et al 1991;Dutra & Bica 2002). Reipurth & Gee (1986) provide a distance estimate to LDN100 of 225 ± 25 pc based on its association with a field star.…”

Section: D5 G308+938mentioning

confidence: 99%

See 3 more Smart Citations

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

A&A

160

View full text Add to dashboard Cite

Context. For the project Galactic cold cores, Herschel photometric observations were carried out as a follow-up of cold regions of interstellar clouds previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold sources and to study its connection to ongoing and future star formation. Aims. We build a catalogue of cold sources within the clouds in 116 fields observed with the Herschel PACS and SPIRE instruments. We wish to determine the general physical characteristics of the cold sources and to examine the correlations with their host cloud properties. Methods. From Herschel data, we computed colour temperature and column density maps of the fields. We estimated the distance to the target clouds and provide both uncertainties and reliability flags for the distances. The getsources multiwavelength source extraction algorithm was employed to build a catalogue of several thousand cold sources. Mid-infrared data were used, along with colour and position criteria, to separate starless and protostellar sources. We also propose another classification method based on submillimetre temperature profiles. We analysed the statistical distributions of the physical properties of the source samples. Results. We provide a catalogue of ∼4000 cold sources within or near star forming clouds, most of which are located either in nearby molecular complexes ( 1 kpc) or in star forming regions of the nearby galactic arms (∼2 kpc). About 70% of the sources have a size compatible with an individual core, and 35% of those sources are likely to be gravitationally bound. Significant statistical differences in physical properties are found between starless and protostellar sources, in column density versus dust temperature, mass versus size, and mass versus dust temperature diagrams. The core mass functions are very similar to those previously reported for other regions. On statistical grounds we find that gravitationally bound sources have higher background column densities (median N bg (H 2 ) ∼ 5 × 10 21 cm −2 ) than unbound sources (median N bg (H 2 ) ∼ 3 × 10 21 cm −2 ). These values of N bg (H 2 ) are higher for higher dust temperatures of the external layers of the parent cloud. However, only in a few cases do we find clear N bg (H 2 ) thresholds for the presence of cores. The dust temperatures of cloud external layers show clear variations with galactic location, as may the source temperatures. Conclusions. Our data support a more complex view of star formation than in the simple idea of a column density threshold. They show a clear influence of the surrounding UV-visible radiation on how cores distribute in their host clouds with possible variations on the Galactic scale.

show abstract

Section: D1 G002+1802supporting

confidence: 84%

Section: D6 G372+2102mentioning

confidence: 95%

Section: D4 G283+2191mentioning

confidence: 99%

Section: D5 G308+938mentioning

confidence: 99%

See 2 more Smart Citations

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

A&A

160

View full text Add to dashboard Cite

show abstract

“…Both clouds lie at similar distances (D150 pc) and have similar masses (D104 de Geus (1992) has shown that both lie near M _ ) ; the edge of an expanding H I shell surrounding the Upper Scorpius subgroup of the Sco-Cen OB association. Lupus is the largest local cloud in our map that has only been observed at resolution (Murphy, Cohen, & May 1986) ; 0¡ .5 roughly 25 deg2 in each cloud has recently been mapped in 13CO with the Nagoya 4 m telescopes (Nozawa et al 1991 ;Tachihara et al 1996).…”

Section: First Quadrantmentioning

confidence: 99%

The Milky Way in Molecular Clouds: A New Complete CO Survey

Dame

Hartmann

Thaddeus

2001

ApJ

2,146

178

2,713

View full text Add to dashboard Cite

New large-scale CO surveys of the Ðrst and second Galactic quadrants and the nearby molecular cloud complexes in Orion and Taurus, obtained with the CfA 1.2 m telescope, have been combined with 31 other surveys obtained over the past two decades with that instrument and a similar telescope on Cerro Tololo in Chile, to produce a new composite CO survey of the entire Milky Way. The survey consists of 488,000 spectra that Nyquist or beamwidth sample the entire Galactic plane over a (1 8 ¡) strip 4¡È10¡ wide in latitude, and beamwidth or sample nearly all large local clouds at higher lati-1 4 ¡ tudes. Compared with the previous composite CO survey of Dame et al. (1987), the new survey has 16 times more spectra, up to 3.4 times higher angular resolution, and up to 10 times higher sensitivity per unit solid angle. Each of the component surveys was integrated individually using clipping or moment masking to produce composite spatial and longitude-velocity maps of the Galaxy that display nearly all of the statistically signiÐcant emission in each survey but little noise.The composite maps provide detailed information on individual molecular clouds, suggest relationships between clouds and regions widely separated on the sky, and clearly display the main structural features of the molecular Galaxy. In addition, since the gas, dust, and Population I objects associated with molecular clouds contribute to the Galactic emission in every major wavelength band, the precise kinematic information provided by the present survey will form the foundation for many large-scale Galactic studies.A map of molecular column density predicted from complete and unbiased far-infrared and 21 cm surveys of the Galaxy was used both to determine the completeness of the present survey and to extrapolate it to the entire sky at o b o \ 32¡. The close agreement of the observed and predicted maps implies that only D2% of the total CO emission at o b o \ 32¡ lies outside our current sampling, mainly in the regions of Chamaeleon and the Gum Nebula. Taking into account this small amount of unobserved emission, the mean molecular column density decreases from D3 ] 1020 cm~2 at o b o \ 5¡ to D0.1 ] 1020 cm~2 at o b o \ 30¡ ; this drop is D6 times steeper than would be expected from a planeparallel layer, but is consistent with recent measurements of the mean molecular column density at higher latitudes.The ratio of the predicted molecular column density map to the observed CO intensity map provides a calibration of the mass conversion factor Out of the Galactic plane, X shows little systematic variation with latitude from a mean value of (1.8^0.3) ] 1020 cm~2 K~1 km~1 s. Given the large sky area and large quantity of CO data analyzed, we conclude that this is the most reliable measurement to date of the mean X value in the solar neighborhood.

show abstract

On the distance to the Ophiuchus star‐forming region

2008

View full text Add to dashboard Cite

The Ophiuchus molecular cloud complex has produced in Lynds 1688 the richest known embedded cluster within ∼300 pc of the Sun. Unfortunately, distance estimates to the Oph complex vary by nearly ∼40% (∼120-165 pc). Here I calculate a new independent distance estimate of 135 ± 8 pc to this benchmark star-forming region based on Hipparcos trigonometric parallaxes to stars illuminating reflection nebulosity in close proximity to Lynds 1688. Combining this value with recent distance estimates from reddening studies suggests a consensus distance of 139 ± 6 pc (4% error), situating it within ∼11 pc of the centroid of the ∼5 Myr old Upper Sco OB subgroup of Sco OB2 (145 pc

show abstract

A study of (C-13)O cloud cores in Ophiuchus

Cited by 56 publications

References 0 publications

Galactic cold cores

Galactic cold cores

The Milky Way in Molecular Clouds: A New Complete CO Survey

On the distance to the Ophiuchus star‐forming region

Contact Info

Product

Resources

About