X‐Ray Shadows by High‐latitude Molecular Clouds. I. Cartography

Küntz, K. D.; Snowden, S. L.; Verter, Frances

doi:10.1086/304303

Cited by 34 publications

(27 citation statements)

References 36 publications

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“…The distance determination by Hearty et al (2000) places it between 112 and 160 pc. Based on X-ray measurements, Kuntz et al (1997) suggested that L1642 is within or close to the edge of the local bubble, which in this Send offprint requests to: D. Russeil, e-mail: delphine.russeil@oamp.fr Based on observations collected at the European Southern Observatory.…”

Section: Introductionmentioning

confidence: 92%

Morphology and kinematics of Lynds 1642

Russeil

Juvela

Lehtinen

et al. 2003

A&A

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Abstract. The high latitude translucent molecular cloud L1642 has been mapped in the J = 1-0 and J = 2-1 transitions of 12 CO, 13 CO and C 18 O using the SEST radio telescope. We have analysed the morphology and velocity structure of the cloud using the Positive Matrix Factorization (PMF) method. The results show that L1642 is composed of a main structure at radial velocity 0.2 km s −1 while the higher velocity components at ∼0.5 and 1.0 km s −1 form an incomplete ring around it, suggesting an expanding shell structure. Fainter emission extends to the north with a still higher velocity of up to 1.6 km s −1 . Such a velocity structure suggests an elongated morphology in the line of sight direction. The physical properties of the cloud have been investigated assuming LTE conditions, but non-LTE radiative transfer models are also constructed for the 13 CO observations. We confirm that L1642 follows an r −1 density distribution in its outer parts while the distribution is considerably flatter in the core. The cloud is close to virial equilibrium. In an Appendix the PMF results are compared with the view obtained through the analysis of channel maps and by the use of Principal Component Analysis (PCA). Both PMF and PCA present the observations as a linear combination of basic spectral shapes that are extracted from the data. Comparison of the methods shows that the PMF method in particular is able to produce a presentation of the complex velocity that is both compact and easily interpreted.

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Section: Introductionmentioning

confidence: 92%

Morphology and kinematics of Lynds 1642

Russeil

Juvela

Lehtinen

et al. 2003

A&A

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“…The different clouds are marked in Hearty et al (2000) determined the distance of L1642 to be 112-160 pc. The X-ray observations of Kuntz et al (1997) suggested that the cloud is close to the edge of the Local Bubble, and not necessarily inside the Orion-Eridanus Bubble, indicating a distance of approximately 140 pc according to Sfeir et al (1999). See Welsh & Shelton (2009) for a description of the Local Bubble.…”

Section: Introductionmentioning

confidence: 93%

Multiwavelength study of the high-latitude cloud L1642: chain of star formation

Malinen

Juvela

Zahorecz

et al. 2014

A&A

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Context. L1642 is one of the two high galactic latitude (|b| > 30 • ) clouds confirmed to have active star formation. Aims. We examine the properties of this cloud, especially the large-scale structure, dust properties, and compact sources at different stages of star formation.Methods. We present high-resolution far-infrared and submillimetre observations with the Herschel and AKARI satellites and millimetre observations with the AzTEC/ASTE telescope, which we combined with archive data from near-and mid-infrared (2MASS, WISE) to millimetre wavelength observations (Planck).Results. The Herschel observations, combined with other data, show a sequence of objects from a cold clump to young stellar objects (YSOs) at different evolutionary stages. Source B-3 (2MASS J04351455-1414468) appears to be a YSO forming inside the L1642 cloud, instead of a foreground brown dwarf, as previously classified. Herschel data reveal striation in the diffuse dust emission around the cloud L1642. The western region shows striation towards the NE and has a steeper column density gradient on its southern side. The densest central region has a bow-shock like structure showing compression from the west and has a filamentary tail extending towards the east. The differences suggest that these may be spatially distinct structures, aligned only in projection. We derive values of the dust emission cross-section per H nucleon of σ e (250 μm) = 0.5−1.5 × 10 −25 cm 2 /H for different regions of the cloud. Modified black-body fits to the spectral energy distribution of Herschel and Planck data give emissivity spectral index β values 1.8-2.0 for the different regions. The compact sources have lower β values and show an anticorrelation between T and β. Conclusions. Markov chain Monte Carlo calculations demonstrate the strong anticorrelation between β and T errors and the importance of millimetre wavelength Planck data in constraining the estimates. L1642 reveals a more complex structure and sequence of star formation than previously known.

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“…Nonetheless, they also required some local emission, although the required amount was somewhat uncertain. Since then, Kuntz et al (1997) studied the foreground X-ray emission by analyzing the shadows seen by ROSAT toward nearby molecular clouds. They measured the foreground R12 emission seen toward nine clouds, finding a range of 3790-6190 counts s À1 sr…”

Section: à2mentioning

confidence: 99%

“…Their results showed substantial variation from position to position, with a mean and standard deviation of 5810 AE 1960 counts s À1 sr À1 . Based on these results, we decided to require at least 910 counts s À1 sr À1 in the R12 band, far below the value found by Kuntz et al (1997) and 2.5 below the Snowden et al (2000) mean value.…”

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confidence: 98%

ChandraObservations of MBM 12 and Models of the Local Bubble

Edgar

Plucinsky

Wargelin

et al. 2005

ApJ

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Chandra observations toward the nearby molecular cloud MBM 12 show unexpectedly strong and nearly equal foreground O viii and O vii emission. As the observed portion of MBM 12 is optically thick at these energies, the emission lines must be formed nearby, coming from either the Local Bubble (LB) or charge exchange with ions from the Sun. Equilibrium models for the LB predict stronger O vii than O viii, so these results suggest that the LB is far from equilibrium or that a substantial portion of O viii is from another source, such as charge exchange within the solar system. Despite the likely contamination, we can combine our results with other EUVand X-ray observations to reject LB models that posit a cool recombining plasma as the source of LB X-rays. Subject headingg s: ISM: bubbles -plasmas -supernova remnants -X-rays: ISM Online material: color figure

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X‐Ray Shadows by High‐latitude Molecular Clouds. I. Cartography

Cited by 34 publications

References 36 publications

Morphology and kinematics of Lynds 1642

Morphology and kinematics of Lynds 1642

Multiwavelength study of the high-latitude cloud L1642: chain of star formation

ChandraObservations of MBM 12 and Models of the Local Bubble

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