Study of Molecular Clouds and Star Formation in the Region of IC 2118

Kun, M.; Aoyama, Hiroko; Yoshikawa, Norihiko; Kawamura, Akiko; Yonekura, Yoshinori; Onishi, Toshikazu; Fukui, Y.

doi:10.1093/pasj/53.6.1063

Cited by 17 publications

(35 citation statements)

References 21 publications

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“…We follow the careful discussion on the distance of this cloud by Kun et al (2001), and adopt their estimate of 210 ± 30 pc with a reliability flag of 2.…”

Section: D82 G20633-2594mentioning

confidence: 99%

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

A&A

160

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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.

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“…We follow the careful discussion on the distance of this cloud by Kun et al (2001), and adopt their estimate of 210 ± 30 pc with a reliability flag of 2.…”

Section: D82 G20633-2594mentioning

confidence: 99%

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

A&A

160

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“…11. is situated at ∼210 pc (Kun et al 2001), and it is possible that the pillar of L1642 is directed towards the viewer. These pillars can be seen already in the earlier IRAS data.…”

Section: Structure and Evolution Of L1642mentioning

confidence: 99%

“…However, even the radial velocity of IC 2118 is only +4 km s −1 and thus the structures that appear to be connected in the projection may be continuous structures also in real space, in spite of the wide range of estimated distances, 140 pc for L1642 and 210 pc for IC 2118 at the other end of the filamentary structures. IC 2118 is likely to be inside the Orion-Eridanus bubble and is directly affected by the massive star towards equatorial east (Kun et al 2001). In contrast, L1642 appears to be beyond the influence of the Orion region and is mainly affected by a flow from the west or is itself travelling west through the ambient medium.…”

Section: Structure and Evolution Of L1642mentioning

confidence: 99%

“…The cloud is projected on the edge of the Orion-Eridanus Bubble (Brown et al 1995). On the sky, L1642 is ∼10 • from the filamentary reflection nebula IC 2118, or Witch Head nebula, which also contains the molecular clouds MBM 21 and 22 (Kun et al 2001(Kun et al , 2004Alcalá et al 2008). The different clouds are marked in Hearty et al (2000) determined the distance of L1642 to be 112-160 pc.…”

Section: Introductionmentioning

confidence: 99%

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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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“…They lie at the southernmost part of an extended reflection nebula, IC 2118 (Witch Head Nebula), illuminated by β Orionis (Rigel). A 12 CO survey performed with the 4-m NANTEN radio telescope and covering the whole area of IC 2118 (Kun et al 2001, hereinafter Paper I) resulted in the detection of six molecular clouds in the bright region, including MBM 21…”

Section: Introductionmentioning

confidence: 99%

The IC 2118 association: New T Tauri stars in high-latitude molecular clouds

Kun

Prusti

Nikolić

et al. 2004

A&A

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Abstract. We identified new pre-main sequence stars in the region of high-latitude molecular clouds associated with the reflection nebula IC 2118, around l ∼ 208• and b ∼ −27• . The stars were selected as T Tauri candidates in objective prism plates obtained with the Schmidt telescope of Konkoly Observatory. Results of spectroscopic follow-up observations, carried out with the FLAIR spectrograph installed on the UK Schmidt and with ALFOSC on Nordic Optical Telescope, are presented in this paper. Based on spectral types, presence of emission lines and lithium absorption line, we identified five classical T Tauri stars and a candidate weak-line T Tauri star projected on the molecular clouds, as well as two candidate pre-main sequence stars outside the nebulous region. Using the near infrared magnitudes obtained from the 2MASS All Sky Catalog (IPAC 2003) we determined the masses and ages of these stars. We found that the five classical T Tauri stars projected on the clouds are physically related to them, whereas the other stars are probably background objects. Adopting a distance of 210 pc for IC 2118 (Kun et al. 2001) and using Palla & Stahler's (1999) evolutionary tracks we derived an average age of 2.5 × 10 6 yrs and a mass interval of 0.4-1.0 M for the members of the IC 2118 association.

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Study of Molecular Clouds and Star Formation in the Region of IC 2118

Cited by 17 publications

References 21 publications

Galactic cold cores

Galactic cold cores

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

The IC 2118 association: New T Tauri stars in high-latitude molecular clouds

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