J/A+A/615/A158 Data cubes of observed species toward Messier 8 (Tiwari+, 2018)
Unveiling the remarkable photodissociation region of Messier 8.
Tiwari M., Menten K.M., Wyrowski F., Perez-Beaupuits J.P., Wiesemeyer H.,
Gusten R., Klein B., Henkel C.
<Astron. Astrophys. 615, A158 (2018)>
=2018A&A...615A.158T 2018A&A...615A.158T (SIMBAD/NED BibCode)
ADC_Keywords: H II regions ; Interstellar medium ; Stars, bright
Keywords: ISM: general - ISM: individual objects: M8 - submillimeter: ISM -
HII regions - ISM: clouds
Abstract:
Messier 8 (M8) is one of the brightest HII regions in the sky. We
collected an extensive dataset comprising multiple submillimeter
spectral lines from neutral and ionized carbon and from CO. Based on
this dataset, we aim to understand the morphology of M8 and that of
its associated photodissociation region (PDR) and to carry out a
quantitative analysis of the physical conditions of these regions such
as kinetic temperatures and volume densities.
We used the Stratospheric Observatory For Infrared Astronomy (SOFIA),
the Atacama Pathfinder Experiment (APEX) 12m, and the Institut de
Radioastronomie Millimetrique (IRAM) 30m telescopes to perform a
comprehensive imaging survey of the emission from the fine structure
lines of CII and CI and multiple rotational transitions of carbon
monoxide (CO) isotopologs within 1.3x1.3pc around the dominant
Herschel 36 (Her 36) system, which is composed of at least three
massive stars. To further explore the morphology of the region, we
compared archival infrared, optical, and radio images of the nebula
with our newly obtained fine structure line and CO data, and in
particular with the velocity information these data provide. We
performed a quantitative analysis, using both LTE and non-LTE methods
to determine the abundances of some of the observed species, kinetic
temperatures, and volume densities.
Bright CO, CII and CI emission have been found toward the HII region
and the PDR in M8. Our analysis places the bulk of the molecular
material in the background of the nebulosity illuminated by the bright
stellar systems Her 36 and 9 Sagitarii. Since the emission from all
observed atomic and molecular tracers peaks at or close to the
position of Her 36, we conclude that the star is still physically
close to its natal dense cloud core and heats it. A veil of warm gas
moves away from Her 36 toward the Sun and its associated dust
contributes to the foreground extinction in the region. One of the
most prominent star forming regions in M8, the Hourglass Nebula, is
particularly bright due to cracks in this veil close to Her 36. We
obtain H2 densities ranging from ∼104-106cm-3 and kinetic
temperatures of 100-150K in the bright PDR caused by Her 36 using
radiative transfer modeling of various transitions of CO isotopologs.
Description:
Data cubes of the observed CII, CI and various CO rotational
transitions toward M8. They contain both temperature and velocity
information of the CII, CI and CO emission in a region ∼120"x120"
around the bright stellar system Herschel 36.
Objects:
-------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------
18 03 37 -24 23.2 M8 = NAME Lagoon Nebula
-------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 112 16 List of fits data cubes
fits/* . 16 Individual fits data cubes
--------------------------------------------------------------------------------
See also:
J/A+A/395/499 : XMM observations in M8 and NGC6530 (Rauw+, 2002)
J/MNRAS/407/1170 : IRAC photometry of M8 (Kumar+, 2010)
J/MNRAS/453/1026 : Lagoon Nebula M8 T tauri accretion rates (Kalari+, 2015)
J/A+A/604/A135 : Dynamics of ionized and neutral gas in M8 (Damiani+, 2017)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 21 I2 --- Nx Number of pixels along X-axis
23- 24 I2 --- Ny Number of pixels along Y-axis
26- 29 I4 --- Nz Number of slices
31- 38 F8.1 km/s bVRAD Lower value of radial velocity interval
40- 47 F8.1 km/s BVRAD Upper value of radial velocity interval
49- 57 F9.4 km/s dVRAD Radial velocity resolution
59- 63 I5 Kibyte size Size of FITS file
65- 79 A15 --- FileName Name of FITS file, in subdirectory fits
81-112 A32 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Maitraiyee Tiwari, mtiwari(at)mpifr-bonn.mpg.de
(End) Maitraiyee Tiwari [MPIfR, Germany], Patricia Vannier [CDS] 31-Jul-2018