J/A+A/612/A81 NGC 300 giant dust clouds (Riener+, 2018)
Gathering dust: A galaxy-wide study of dust emission from cloud complexes
in NGC 300.
Riener M., Faesi C.M., Forbrich J., Lada C.J.
<Astron. Astrophys. 612, A81 (2018)>
=2018A&A...612A..81R 2018A&A...612A..81R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby
Keywords: methods: observational - galaxies: star formation - ISM: clouds
Abstract:
We use multi-band observations by the Herschel Space Observatory to
study the dust emission properties of the nearby spiral galaxy NGC
300. We compile a first catalogue of the population of giant dust
clouds (GDCs) in NGC 300, including temperature and mass estimates,
and give an estimate of the total dust mass of the galaxy.
We carried out source detection with the multiwavelength source
extraction algorithm getsources. We calculated physical properties,
including mass and temperature, of the GDCs from five-band Herschel
PACS and SPIRE observations from 100-500µm; the final size and
mass estimates are based on the observations at 250µm that have an
effective spatial resolution of ∼170pc. We correlated our final
catalogue of GDCs to pre-existing catalogues of HII regions to infer
the number of GDCs associated with high-mass star formation and
determined the Hα emission of the GDCs.
Our final catalogue of GDCs includes 146 sources, 90 of which are
associated with known HII regions. We find that the dust masses of the
GDCs are completely dominated by the cold dust component and range
from ∼1.1x103 to 1.4x104M☉. The GDCs have effective
temperatures of ∼13-23K and show a distinct cold dust effective
temperature gradient from the centre towards the outer parts of the
stellar disk. We find that the population of GDCs in our catalogue
constitutes ∼16% of the total dust mass of NGC 300, which we estimate
to be about 5.4x106M_☉. At least about 87% of our GDCs have a
high enough average dust mass surface density to provide sufficient
shielding to harbour molecular clouds. We compare our results to
previous pointed molecular gas observations in NGC 300 and results
from other nearby galaxies and also conclude that it is very likely
that most of our GDCs are associated with complexes of giant molecular
clouds.
Description:
We obtained photometric observations of NGC 300 with the Herschel
Space Observatory (PI: Jan Forbrich) with two of its instruments,the
Spectral and Photometric Imaging Receiver (SPIRE) and the
Photodetector Array Camera and Spectrometer (PACS).
The SPIRE observations took place on 2012 May 11 with a total exposure
time of 4558s.
The two PACS observations were carried out on 2012 June 25 with a
total exposure time of 3245 and 3803s.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 181 146 Catalogue of giant dust clouds
figd1.pdf 512 36329 Footprint of GDCs
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See also:
J/ApJ/821/125 : SMA obs. of giant molecular clouds in NGC 300 (Faesi+, 2016)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/146] Giant dust cloud (GDC) catalog
identifier
5- 7 A3 --- f_Seq Footnotes (1)
9- 16 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
18- 26 F9.5 deg DEdeg Declination in decimal degrees (J2000)
28 A1 --- l_F100 [<] Limit flag on F100
29- 34 F6.1 mJy F100 ?=- Flux at 100 microns
36- 39 F4.1 mJy e_F100 ? Uncertainty in F100
41 A1 --- l_F160 [<] Limit flag on F160
42- 47 F6.1 mJy F160 ?=- Flux at 160 microns
49- 52 F4.1 mJy e_F160 ? Uncertainty in F160
54 A1 --- l_F250 [<] Limit flag on F250
55- 59 F5.1 mJy F250 Flux at 250 microns
61- 64 F4.1 mJy e_F250 ? Uncertainty in F250
66 A1 --- l_F350 [<] Limit flag on F350
67- 71 F5.1 mJy F350 Flux at 350 microns
73- 76 F4.1 mJy e_F350 ? Uncertainty in F350
78 A1 --- l_F500 [<] Limit flag on F500
79- 83 F5.1 mJy F500 Flux at 500 microns
85- 88 F4.1 mJy e_F500 ? Uncertainty in F500
90- 93 F4.1 arcsec amaj Size estimate of major axis
95- 98 F4.1 arcsec bmin Size estimate of minor axis
100-104 F5.1 deg theta Rotational angle (east of the vertical
axis) of amaj
106-110 F5.3 kpc D Deprojected galactocentric distance
112-116 F5.1 pc Deq Diameter of equivalent circular area
118-122 F5.2 K Tcold ?=- Cold dust effective temperature
124-127 F4.1 1000Msun Mdust ?=- Dust mass
129-131 F3.1 1000Msun e_Mdust ? Uncertainty in Mdust
133-136 F4.1 mJy F24 Flux at 24 microns
138-140 F3.1 mJy e_F24 Uncertainty in F24
142 A1 --- l_FHa [<] Limit flag on FHa
143-147 F5.1 10-17W/m2 FHa Halpha flux (in 10-14erg/cm2/s)
149-152 F4.1 10-17W/m2 e_FHa ? Uncertainty in FHa
(in 10-14erg/cm2/s)
154-181 A28 --- HII Associated Deharveng et al.
(1988A&AS...73..407D 1988A&AS...73..407D) HII regions
([DCL88] NNNA in Simbad) (2)
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Note (1): Footnotes as follows:
a = Sources labelled as tentative by getsources
b = Sources added from source extraction for SPIRE-images only
c = Strongly deblended with another discarded source candidate; flux of
discarded source candidate was added to this source
d = Position incorrectly shifted due to background galaxy
e = Uncertain temperature estimate
f = Size estimate likely too high
Note (2): From Deharveng et al. (1988A&AS...73..407D 1988A&AS...73..407D); (D), (M), (N)
indicate detections, marginal detections and non-detections in CO(J=2-1),
respectively, from Faesi et al. (2014ApJ...789...81F 2014ApJ...789...81F)
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Acknowledgements:
Manuel Riener, riener(at)mpia.de
(End) Manuel Riener [MPIA, Germany], Patricia Vannier [CDS] 22-Nov-2017