J/A+A/687/A162 The effects of stellar feedback on clumps in M8 (Kahle+, 2024)
The effects of stellar feedback on molecular clumps in the Lagoon Nebula (M8).
Kahle K.A., Wyrowski F., Koenig C., Christensen I.B., Tiwari M., Menten K.M.
<Astron. Astrophys. 687, A162 (2024)>
=2024A&A...687A.162K 2024A&A...687A.162K (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Radio lines ; Line Profiles ; Abundances
Keywords: techniques: spectroscopic - stars: protostars - ISM: clouds -
photon-dominated region (PDR) - ISM: individual objects: M8
Abstract:
The Lagoon Nebula (M8) is host to multiple regions with recent and
ongoing massive star formation. The 37 known molecular clumps in M8
are affected by the presence of massive O- and B-type stars. We
establish an inventory of molecular species in M8 by conducting an
unbiased line survey for each clump. Additional archival data from the
Spitzer, Herschel, MSX, APEX, WISE, JCMT and AKARI telescopes are used
to derive physical parameters of the dust emission. We identify 346
transitions from 70 different species. While many are exclusively seen
toward M8 East, the other clumps also show a large chemical variety.
We detect tracers of photo-dissociation regions across all the clumps
and 38% of these clumps show signs of star formation. We find that PDR
tracers are most abundant in clumps with relatively lower H2 column
densities. When comparing M8 clumps to ATLASGAL sources at similar
distances, we find them to be slightly less massive and have
compatible luminosities and radii. This possibly indicates a
fragmentation of the gas caused by the O- and B-type stars. In
contrast, dust temperatures of the clumps in M8 are found to be
increased by approximately 5K (25%) indicating substantial external
heating of the clumps by radiation of the present massive stars.
Description:
We used APEX and the IRAM 30m telescope for pointed on-off
observations on the 37 molecular clumps in M8. These observations
cover bandwidths of 53GHz and 40GHz in frequency ranges from 210GHz to
280GHz and from 70GHz to 117GHz, respectively. Across the observed M8
region, we identify 346 transitions from 70 different molecular
species, including isotopologues. We fit the line profiles with up to
two Gaussian components. For transitions with resolved hyperfine
structure, we use the HFS method of the MINIMIZE function of CLASS to
fit all components simultaneously. We derive column densities for all
species detected in M8 at all clumps. Upper limits are derived based
on the spectrum root mean square (RMS) noise if a species detected in
M8 is not detected in a specific clump. For deriving column densities,
we assume local thermodynamic equilibrium and optically thin emission.
We approximate the kinetic temperatures of the clumps with their dust
temperatures.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 25 37 Coordinates of all the clumps observed with
the APEX and the IRAM 30m telescopes
tabled1.dat 130 346 Transitions identified in M8
tabled2.dat 167 10527 Fits to the line profiles
tableg1.dat 45 2590 Derived column densities
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Clump Clump designation
4 A1 --- n_Clump [*] Note on Clump (1)
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 15 F4.1 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 25 I2 arcsec DEs Declination (J2000)
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Note (1): For clumps marked with an asterisk, we used corrected coordinates
when observing with the IRAM 30m telescope and when extracting flux density
from the dust continuum maps as
WC3: 18 03 44.8 -24 21 03
SE8: 18 04 50.5 -24 27 33
SC5: 18 03 40.7 -24 26 59
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Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Species Name of the species
17- 36 A20 --- qn Description of transition
38- 47 F10.3 MHz Freq Transition frequency
49- 51 I3 kHz e_Freq Uncertainty on transition frequency
53- 57 F5.1 K Eup Upper level energy
59- 65 E7.2 s-1 Aij Einstein A coefficient
67- 69 I3 --- g Degeneracy
71- 74 A4 --- Origin Origin database (catalog)
76- 96 A21 --- Speciesl Species in LaTeX notation
98-130 A33 --- qnl Transition description in LaTeX notation
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Byte-by-byte Description of file: tabled2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Source Name of the clump in M8 (M8Clump)
7- 27 A21 --- Species Species in LaTeX notation
29- 35 F7.3 MHz Freq Transition frequency
37- 41 F5.1 mK rms Root mean square noise of spectrum
43- 48 F6.2 K.km/s Iint ?=- Line intensity from integrating
channels (3)
50- 53 F4.2 K.km/s e_Iint ?=- Error on integrated line intensity (3)
55- 60 F6.2 K.km/s Ifit1 ?=- Line intensity of component 1 from fit (3)
62- 66 F5.2 K.km/s e_Ifit1 ?=- Error on fit intensity of component 1 (3)
68- 72 F5.2 km/s v1 ?=- LOS velocity of component 1
from fit (3) (1)
74- 78 F5.2 km/s e_v1 ?=- Error on fit LOS velocity of
component 1 (3)
80- 84 F5.2 km/s Deltav1 ?=- FWHM line width of component 1
from fit (3)
86- 90 F5.2 km/s e_Deltav1 ?=- Error on fit FWHM width of component 1 (3)
92- 96 F5.2 K Tpeak1 ?=- Peak temperature of component 1
from fit (3)
98-101 F4.2 K e_Tpeak1 ?=- Error on Tpeak1 (3)
103-107 F5.2 --- tau1 ?=- optical depth of component 1
from fit (3) (2)
109-113 F5.2 --- e_tau1 ?=- Error on optical depth of component 1 (3)
115-119 F5.2 K.km/s Ifit2 ?=- Line intensity of component 2 from fit (3)
121-124 F4.2 K.km/s e_Ifit2 ?=- Error on fit intensity of component 2 (3)
126-130 F5.2 km/s v2 ?=- LOS velocity of component 2
from fit (3) (1)
132-135 F4.2 km/s e_v2 ?=- Error on fit LOS velocity of
component 2 (3)
137-140 F4.2 km/s Deltav2 ?=- FWHM line width of component 2
from fit (3)
142-145 F4.2 km/s e_Deltav2 ?=- Error on fit FWHM width of component 2 (3)
147-151 F5.2 K Tpeak2 ?=- Peak temperature of component 2
from fit (3)
153-156 F4.2 K e_Tpeak2 ?=- Error on Tpeak2 (3)
158-161 F4.2 --- tau2 ?=- Optical depth of component 2
from fit (3) (2)
163-167 F5.2 --- e_tau2 ?=- Error on optical depth of component 2 (3)
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Note (1): Line of sight (LOS) velocities are calculated with respect to the
local standard of rest.
Note (2): the optical depth is only obtained when using the HFS method.
Note (3): --- value marks non-detections (if Iint is ---),
line candidates (if Iint is not ---), lines with just a single component
(if Ifit1 or Ifit2 is not ---), or lines that we could not fit (also if Iint
is not ---). Missing fits for detected transitions are mostly caused by strong
line blending, i.e. when different transitions are blended in sources with
multiple line components.
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Byte-by-byte Description of file: tableg1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Source Name of the clump in M8 (M8Clump)
7- 27 A21 --- Species Species in LaTeX notation
29- 35 E7.1 cm-2 NSpecies1 ?=- Column density of species based on
Gaussian component 1
37- 43 E7.1 cm-2 NSpecies2 ?=- Column density of species based on
Gaussian component 2
45 I1 --- l_NSpecies1 [0/1] 1 if value is an upper limit, 0 if not
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Acknowledgements:
Kim Angelique Kahle, kahle(at)mpia.de, Max Planck Institute for Astronomy
(End) K. Kahle [Max Planck Inst. for Astron.], P. Vannier [CDS] 15-Apr-2024