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LIE97 - Thermal methanol emission in the DR21 complex. Interferometric maps: a comparison with maser emission.

Short title: Liechti & Walmsley (1997)
Authors: Liechti, S. Walmsley, C. M.
Journal: Astronomy and Astrophysics, v.321, p.625-633
Bibcode:

Target type: High_mass_SFR
Transitions: CH3OH_44(I),CH3OH_95(I),CH3OH_6(II),CH3OH_12(II),CH3OH_108(II),CH3OH_157(II)

Abstract
We present interferometric observations with ~3.5'' resolution of the 2_k_->1_k_ methanol lines towards the methanol masers in the DR21/DR21(OH) complex. These transitions are not masing and hence our measurements can be used to place limits on the methanol mass associated with the maser spots. We do not find in general good correlation between the peaks of 'non-maser' methanol emission and the positions of Class I methanol masers. In particular, we put an upper limit on 2_k_->1_k_ emission towards the 8_0_->7_1_A^+^ maser DR21(OH)-1 from Plambeck and Menten (1990) (hereafter PM90). We do find however evidence for coincidence between the peak of the 2_1_->1_1_E emission in our map with the Class I masers towards DR21-W. We conclude that methanol Class I masers are likely to originate in a region considerably smaller than our synthesised beam (3.5'') and with methanol column density of order 10^16^cm^-2^. It seems reasonable that they might form in regions of diameter 1000AU and mass 0.01M_sun_. Our data also show differences between the distribution of methanol and that of other species which suggest large spatial variations in the methanol abundance. In particular, we see evidence for high methanol column density towards the submillimeter continuum source DR21(OH)-MM1. In the western lobe of the DR21 outflow, the thermal methanol emission appears to be 'sandwiched' between vibrationally excited H_2_ emission, tracing the outflow shock front, and CS emission tracing the dense ambient medium. This is consistent with the idea that methanol can be enhanced in shock regions, where the outflow impinges on the surrounding dense molecular clumps, releasing methanol from dust grain ice mantles.

Abstract

We present interferometric observations with ~3.5'' resolution of the 2_k_->1_k_ methanol lines towards the methanol masers in the DR21/DR21(OH) complex. These transitions are not masing and hence our measurements can be used to place limits on the methanol mass associated with the maser spots. We do not find in general good correlation between the peaks of 'non-maser' methanol emission and the positions of Class I methanol masers. In particular, we put an upper limit on 2_k_->1_k_ emission towards the 8_0_->7_1_A^+^ maser DR21(OH)-1 from Plambeck and Menten (1990) (hereafter PM90). We do find however evidence for coincidence between the peak of the 2_1_->1_1_E emission in our map with the Class I masers towards DR21-W. We conclude that methanol Class I masers are likely to originate in a region considerably smaller than our synthesised beam (3.5'') and with methanol column density of order 10^16^cm^-2^. It seems reasonable that they might form in regions of diameter 1000AU and mass 0.01M_sun_. Our data also show differences between the distribution of methanol and that of other species which suggest large spatial variations in the methanol abundance. In particular, we see evidence for high methanol column density towards the submillimeter continuum source DR21(OH)-MM1. In the western lobe of the DR21 outflow, the thermal methanol emission appears to be 'sandwiched' between vibrationally excited H_2_ emission, tracing the outflow shock front, and CS emission tracing the dense ambient medium. This is consistent with the idea that methanol can be enhanced in shock regions, where the outflow impinges on the surrounding dense molecular clumps, releasing methanol from dust grain ice mantles.

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Detection table from Liechti & Walmsley (1997)

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DSS colored	2MASS colored	WISE colored
SDSS color	IRAC color I1,I2,I4	GLIMPSE 360
PACS color (70-160 um)	SPIRE color (250-500 um)	NVSS (1.4GHz)
ATLASGAL 870 um	ATLASGAL 870 um + Planck	Bolocam 1.1 mm
UKIDSS K Download UKIDSS K FITS	2MASS K Download 2MASS K FITS

select MAX(h2o_data_all.ra_hms) as ra_hms,MAX(h2o_data_all.dec_dms) as dec_dms,MAX(h2o_data_all.source_name) as source_name,MAX(h2o_data_all.ra) as ra,MAX(h2o_data_all.dec) as dec,MAX(h2o_data_all.l) as l,MAX(h2o_data_all.b) as b,MAX(h2o_data_all.grp) as grp,MAX(h2o_data_all.other_name) as other_name,MAX(h2o_data_all.other_desc) as other_desc,BOOL_OR(thermal) as thermal,MAX(h2o_data_all.vrange) as vrange,MAX(h2o_data_all.vpeak) as vpeak,MAX(h2o_data_all.peak) as peak,MAX(h2o_data_all.fwhm) as fwhm,MAX(h2o_data_all.int) as int,MAX(h2o_data_all.rms) as rms,MAX(h2o_data_all.units) as units,MAX(h2o_data_all.units_rms) as units_rms,MAX(h2o_data_all.date_txt) as date_txt,MAX(h2o_data_all.telescope_ref) as telescope_ref,MAX(h2o_data_all.telescope_conf) as telescope_conf,MAX(h2o_data_all.v_step) as v_step,MAX(h2o_data_all.beam) as beam,MAX(h2o_data_all.beam_maj) as beam_maj,MAX(h2o_data_all.beam_min) as beam_min,MAX(h2o_data_all.beam_pa) as beam_pa,MAX(h2o_data_all.ref) as ref,MAX(h2o_data_all.list_ref) as list_ref,MAX(h2o_data_all.ascii) as ascii,MAX(h2o_data_all.url) as url,MAX(h2o_data_all.image) as image,MAX(h2o_data_all.image2) as image2,MAX(h2o_data_all.image3) as image3,MAX(h2o_data_all.descr) as descr,MAX(h2o_data_all.id) as id,BOOL_OR(mjy_flag) as mjy_flag,BOOL_OR(rms_mjy_flag) as rms_mjy_flag,MAX(h2o_data_all.dist) as dist,1 as dist_parallax,MAX(h2o_data_all.date_txt) as date_txt,MAX(line_det) as line_det,MAX(type) as type,MAX(simbad_types_cat) as simbad_types_cat FROM h2o_data_all  LEFT JOIN all_objects_withmet ON h2o_data_all.grp=all_objects_withmet.group_name LEFT JOIN object_categories ON all_objects_withmet.group_name = object_categories.group_name_cat AND object_categories.tbl_cat = 'all_objects_withmet' WHERE ref ilike 'LIE97' AND detected=true AND hide=false GROUP BY ref

select h2o_data_all.ra_hms,h2o_data_all.dec_dms,h2o_data_all.source_name,h2o_data_all.ra,h2o_data_all.dec,h2o_data_all.l,h2o_data_all.b,h2o_data_all.grp,h2o_data_all.other_name,h2o_data_all.other_desc,h2o_data_all.thermal,h2o_data_all.vrange,h2o_data_all.vpeak,h2o_data_all.peak,h2o_data_all.fwhm,h2o_data_all.int,h2o_data_all.rms,h2o_data_all.units,h2o_data_all.units_rms,h2o_data_all.date_txt,h2o_data_all.telescope_ref,h2o_data_all.telescope_conf,h2o_data_all.v_step,h2o_data_all.beam,h2o_data_all.beam_maj,h2o_data_all.beam_min,h2o_data_all.beam_pa,h2o_data_all.ref,h2o_data_all.list_ref,h2o_data_all.ascii,h2o_data_all.url,h2o_data_all.image,h2o_data_all.image2,h2o_data_all.image3,h2o_data_all.descr,h2o_data_all.id,h2o_data_all.mjy_flag,h2o_data_all.rms_mjy_flag,h2o_data_all.dist,h2o_data_all.dist_parallax,h2o_data_all.date_txt,line_det,type,simbad_types_cat FROM h2o_data_all   LEFT JOIN all_objects_withmet ON h2o_data_all.grp=all_objects_withmet.group_name LEFT JOIN object_categories ON all_objects_withmet.group_name = object_categories.group_name_cat AND object_categories.tbl_cat = 'all_objects_withmet' WHERE ref ilike 'LIE97' AND detected=true AND hide=false ORDER BY detected DESC,id

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LIE97 - Thermal methanol emission in the DR21 complex. Interferometric maps: a comparison with maser emission.

View as list of objects

Detection table from Liechti & Walmsley (1997)