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

Abstract

L1642 is one of the two high galactic latitude (|b| > 30deg) clouds confirmed to have active star formation. We examine the properties of this cloud, especially the large-scale structure, dust properties, and compact sources in different stages of star formation. We present high-resolution far-infrared and submm observations with the Herschel and AKARI satellites and mm observations with the AzTEC/ASTE telescope, which we combined with archive data from near- and mid-infrared (2MASS, WISE) to mm observations (Planck). The Herschel observations, combined with other data, show a sequence of objects from a cold clump to young stellar objects 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 L1642. The western region shows striation towards 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 a filamentary tail extending towards 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 for different regions of the cloud. Modified black-body fits to the spectral energy distribution of Herschel and Planck data give emissivity spectral index beta values 1.8-2.0 for the different regions. The compact sources have lower beta values and show an anticorrelation between T and beta. Markov chain Monte Carlo calculations demonstrate the strong anticorrelation between beta and T errors and the importance of mm Planck data in constraining the estimates. L1642 reveals a more complex structure and sequence of star formation than previously known.

22 pages, 18 figures, accepted to Astronomy & Astrophysics; abstract shortened and figures reduced for astroph

References in corpus (13)

• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster
• AzTEC Millimetre Survey of the COSMOS Field: I. Data Reduction and Source Catalogue
• The AzTEC mm-Wavelength Camera
• A VLT/NACO Survey for Triple and Quadruple Systems among Visual Pre-Main Sequence Binaries
• The Trouble with the Local Bubble
• The degeneracy between dust colour temperature and spectral index. Comparison of methods for estimating the beta(T) relation
• Xmm-Newton Observations of the Diffuse X-ray Background
• Southern wide very low-mass stars and brown dwarfs in resolved binary and multiple systems
• Young stellar clusters in the Rosette molecular cloud. Arguments against triggered star formation
• ISO far infrared observations of the high latitude cloud L1642. II. Correlated variations of far-infrared emissivity and temperature of "classical large" dust particles
• Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N
• Newly identified YSO candidates towards the LDN 1188

Cited by in corpus (17)

• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• Galactic cold cores VI. Dust opacity spectral index
• Low temperature MIR to submillimeter mass absorption coefficient of interstellar dust analogues I: Mg-rich glassy silicates
• Matching dust emission structures and magnetic field in high-latitude cloud L1642: comparing Herschel and Planck maps
• Galactic cold cores V. Dust opacity
• Dust properties inside molecular clouds from coreshine modeling and observations
• SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution - Survey Description and Compact Source Catalogue
• Herschel and SCUBA-2 observations of dust emission in a sample of Planck cold clumps
• Galactic cold cores IX. Column density structures and radiative transfer modelling
• Discovery of two embedded clusters with WISE in the high Galactic latitude cloud HRK 81.4-77.8
• The physical properties of Cluster Chains
• Polarization of seven MBM clouds at high galactic latitude
• Optical and UV surface brightness of translucent dark nebulae: Dust albedo, radiation field and fluorescence emission by H2
• Dust emission, extinction, and scattering in LDN 1642
• CO enhancement by magnetohydrodynamic waves; Striations in the Polaris Flare
• Planck Galactic Cold Clumps at High Galactic Latitude-A Study with CO Lines
• On the Scarcity of Dense Cores ($n>10^5$ cm${}^{-3}$) in High Latitude Planck Galactic Cold Clumps