J/MNRAS/404/661 Young stellar outflows near-IR imaging (Varricatt+ 2010)
A near IR imaging survey of intermediate and high-mass young stellar outflow
candidates.
Varricatt W.P., Davis C.J., Ramsay S., Todd S.P.
<Mon. Not. R. Astron. Soc. 404, 661 (2010)>
=2010MNRAS.404..661V 2010MNRAS.404..661V
ADC_Keywords: YSOs ; Infrared sources
Keywords: circumstellar matter - stars: formation - ISM: jets and outflows -
infrared: stars -
Abstract:
We have carried out a near-infrared imaging survey of luminous young
stellar outflow candidates using the United Kingdom Infrared
Telescope. Observations were obtained in the broad band K (2.2um) and
through narrow band filters at the wavelengths of H2 v=1-0 S(1)
(2.1218um) and Br gamma (2.166um) lines. Fifty regions were imaged
with a field of view of 2.2x2.2arcmin2. Several young embedded
clusters are unveiled in our near-infrared images. 76% of the objects
exhibit H2 emission and 50% or more of the objects exhibit aligned
H2 emission features suggesting collimated outflows, many of which
are new detections. These observations suggest that disk accretion is
probably the leading mechanism in the formation of stars, at least up
to late O spectral types. The young stellar objects responsible for
many of these outflows are positively identified in our images based
on their locations with respect to the outflow lobes, 2MASS colours
and association with MSX, IRAS, millimetre and radio sources. The
close association of molecular outflows detected in CO with the H2
emission features produced by shock excitation by jets from the young
stellar objects suggests that the outflows from these objects are
jet-driven. Towards strong radio emitting sources, H2 jets were
either not detected or were weak when detected, implying that most of
the accretion happens in the pre-UCHII phase; accretion and outflows
are probably weak when the YSO has advanced to its UCHII stage.
Description:
These are images of Massive Young Stellar outflow candidates obtained
using the United Kingdom Infrared Telescope (UKIRT) and UFTI (UKIRT
Fast-Track Imager). The pixel scale is 0.091arcsec/pixel. Images
obtained in broad band K (2.2um, MKO) filter and in narrow-band
filters centered at the wavelengths of H2 (2.1218um) and BrGamma
(2.166um) lines are given here. Sky conditions were either photometric
or thin cirrus, as mentioned in the paper. The mosaics presented here
are ∼2.2x2.2arcmin2 across. The images are not flux calibrated. The
images in the three filters, with names ending with "_K.fit",
"_H2.fit" or "_BrG.fit" have the exposure time defined in the fits
keyword "EXP_TIME". For H2 and BrGamma, images after normalization (to
1sec exposure time) and continuum-subtraction (with scaled K-band
images) are also presented. The names of these images end in
"norcs.fit".
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 183 50 List of studied sources
tableb1.dat 60 51 MHO numbers of the H2 line emission features
identified in this paper
(from http://www.jach.hawaii.edu/UKIRT/MHCat/)
fits/* . 236 Individual fits images
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See also:
II/125 : IRAS catalogue of Point Sources, Version 2.0 (IPAC 1986)
Byte-by-byte Description of file: table.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/50] Object sequential number
4- 7 A4 --- --- [IRAS]
9- 18 A10 --- IRAS Object name
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 30 F5.2 s RAs Right ascension (J2000)
32 A1 --- DE- Declination sign (J2000)
33- 34 I2 deg DEd Declination (J2000)
36- 37 I2 arcmin DEm Declination (J2000)
39- 42 F4.1 arcsec DEs Declination (J2000)
44 A1 --- --- [K] Filter
46- 65 A20 --- File.K Filename of image in "fits" subdirectory
67- 71 A5 --- --- [2.122] H2 filter (2.122um)
72- 73 A2 --- Hf [MK] Filter used for H2 (2.122 or 2.122MK) (1)
75- 95 A21 --- File.H Filename of H2 image in "fits" subdirectory
97-124 A28 --- File.Hc Filename of H2 image after normalization
and continuum-subtraction in "fits" subdirectory
126-130 A5 --- --- [BrGam] Filter Bracket γ (2.183um)
132-153 A22 --- File.B Filename of Brγ image (2.183um) in "fits"
subdirectory
155-183 A29 --- File.Bc Filename of Brγ image after normalization
and continuum-subtraction in "fits" subdirectory
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Note (1): the relative transmissions of the H2 filters 2.122 and 2.122MK are
illustrated in the file 2.122_profiles.gif.
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Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/50] Object sequential number
4- 13 A10 --- IRAS Object Name (HHMMm+DDMM)
15- 16 I2 --- NH2 ? H2 feature number (is Seq number)
18 A1 --- --- [-]
20- 28 A9 --- H2ID1 First H2 line emission features
(labelled on Figs. A1-A50)
29 A1 --- --- [;]
31- 34 A4 --- H2ID2 Second H2 line emission features
(labelled on Figs. A1-A50)
36 A1 --- --- [;]
38 I1 --- H2ID3 ? Third H2 line emission features
(labelled on Figs. A1-A50)
40- 48 A9 --- MHO1 MHO number(s) corresponding to H2ID1
49 A1 --- --- [;]
51- 54 I4 --- MHO2 ? MHO number(s) corresponding to H2ID2
55 A1 --- --- [;]
57- 60 I4 --- MHO3 ? MHO number(s) corresponding to H2ID3
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Acknowledgements:
W.P. Varricatt, w.varricatt(at)jach.hawaii.edu
History:
* 02-Jun-2010: table.dat
* 09-Nov-2010: tableb1.dat added
(End) Patricia Vannier [CDS] 26-Jan-2010