480 research outputs found
Revisiting the location and environment of the central engine in NGC1068
We revisit in this paper the location of the various components observed in
the AGN of NGC1068. Discrepancies between previously published studies are
explained, and a new measurement for the absolute location of the K-band
emission peak is provided. It is found to be consistent with the position of
the central engine as derived by Gallimore (1997), Capetti (1997) and Kishimoto
(1999). A series of map overlays is then presented and discussed. Model
predictions of dusty tori show that the nuclear unresolved NIR-MIR emission is
compatible with a broad range of models: the nuclear SED alone does not
strongly constrain the torus geometry, while placing reasonable constraints on
its size and thickness. The extended MIR emission observed within the ionizing
cone is shown to be well explained by the presence of optically thick dust
clouds exposed to the central engine radiation and having a small covering
factor. Conversely, a distribution of diffuse dust particles within the
ionizing cone is discarded. A simple model for the H2 and CO emission observed
perpendicularly to the axis of the ionizing cone is proposed. We show that a
slight tilt between the molecular disc and the Compton thick central absorber
naturally reproduces the observed distribution of H2 of CO emission.Comment: 17 pages, 11 figures, revised version for A&
Embedded clusters in NGC1808 central starburst - Near-infrared imaging and spectroscopy
In the course of a mid-infrared imaging campaign of close-by active galaxies,
we discovered the mid-infrared counterparts of bright compact radio sources in
the central star-forming region of NGC1808. We aim at confirming that these
sources are deeply embedded, young star clusters and at deriving some of their
intrinsic properties. To complement the mid-infrared data, we have collected a
set of near-infrared data with ISAAC at the VLT: J, Ks, and L' images, as well
as low-resolution, long-slit spectra for three of the sources. Surprisingly,
the new images unveil a near-infrared counterpart for only one of the
mid-infrared/radio sources, namely M8 in the L' band. All the other sources are
so deeply embedded that their emission does not pop out above an extended
diffuse near-infrared emission. The near-infrared spectra of the sources look
alike, with intense, ionised hydrogen lines. This supports the interpretation
of these sources in terms of embedded young clusters. We derive extinctions and
ionising photon production rates for two of the clusters.Comment: accepted A&A research note, 7 pages, 4 figures and 1 tabl
The Nature of the Low-Metallicity ISM in the Dwarf Galaxy NGC 1569
We are modeling the spectra of dwarf galaxies from infrared to submillimeter
wavelengths to understand the nature of the various dust components in
low-metallicity environments, which may be comparable to the ISM of galaxies in
their early evolutionary state. The overall nature of the dust in these
environments appears to differ from those of higher metallicity starbursting
systems. Here, we present a study of one of our sample of dwarf galaxies, NGC
1569, which is a nearby, well-studied starbursting dwarf. Using ISOCAM, IRAS,
ISOPHOT and SCUBA data with the Desert et al. (1990) model, we find consistency
with little contribution from PAHs and Very Small Grains and a relative
abundance of bigger colder grains, which dominate the FIR and submillimeter
wavelengths. We are compelled to use 4 dust components, adding a very cold dust
component, to reproduce the submillimetre excess of our observations.Comment: 4 pages, 4 postscript figures. Proceedings of "Infrared and
Submillimeter Astronomy. An International Colloquium to Honor the Memory of
Guy Serra" (2002
Mid-infrared imaging of NGC1068 with VISIR at the VLT
High resolution mid-infrared (MIR) images of the central region of NGC1068
have been obtained with VISIR, the multi-mode MIR instrument recently installed
at the ESO/VLT on Paranal. A map of the emission at 12.8mic with increased
sensitivity over the central 8"x 8" area is discussed. It shows a central core
(unresolved along the E-W direction) and an extended emission which draws a
spiral pattern similar to that observed on near-infrared images. Patches of MIR
emission can be detected up to a distance of 4" from the core. The deconvolved
12.8mic map is fully consistent with previous high-resolution MIR observations.
It highlights the structure of the extended emission, already seen on the
un-deconvolved image, and allows to identify a set of mid-infrared sources: 7
in the NE quadrant and 5 in the SW quadrant. The MIR emission map is compared
with those obtained at comparable angular resolution in the near-infrared and
in the [OIII] line emission. The very good correlation between the VISIR map
and the HST optical map supports the idea that the MIR emission not associated
with the torus arises from dust associated with the narrow line region clouds.
The N-S extension of the MIR core (0.44") is then probably simply due to the
mixing of the MIR emission from the dusty torus and the MIR emission from NLR
cloud B, located only 0.1" to the North.Comment: 5 pages, 1 figure (reduced quality), accepted MNRAS Letter. The paper
with full resolution figure can be downloaded at
http://www.sc.eso.org/~egallian/VISIR/N1068_VISIR.ps.g
High angular resolution near-infrared integral field observations of young star cluster complexes in NGC1365
This paper presents and examines new near-infrared integral field
observations of the three so-called 'embedded star clusters' located in the
nuclear region of NGC1365. Adaptive-optics- corrected K-band data cubes were
obtained with the ESO/VLT instrument SINFONI. The continuum in the K-band and
emission lines such as HeI, Bracket-gamma, and several H2 lines were mapped at
an achieved angular resolution of 0.2arcsec over a field of 3x3arcsec^2 around
each source. We find that the continuum emission of the sources is spatially
resolved. This means that they are indeed cluster complexes confined to regions
of about 50pc extension. We performed robust measurements of the equivalent
width of the CO absorption band at 2.3micro and of Bracket-gamma. For the main
mid-infrared bright sources, the data only allow us to determine an upper limit
to the equivalent width of the CO bands. Under the assumption of an
instantaneously formed standard initial mass function Starburst99 model, the
new measurements are found to be incompatible with previously published
mid-infrared line ratios. We show that an upper mass limit of 25 to 30 solar
masses, lower than the typically assumed 100solar masses, allows one to simply
remove this inconsistency. For such a model, the measurements are consistent
with ages in the range of 5.5Myr to 6.5Myr, implying masses in the range from 3
to 10 x 10^6 solar masses. We detect extended gas emission both in HII and H2.
We argue that the central cluster complexes are the sources of excitation for
the whole nebulae, through ionisation and shock heating. We detect a blue wing
on the Bracket-gamma emission profile, suggesting the existence of gas outflows
centred on the cluster complexes. We do not find any evidence for the presence
of a lower mass cluster population, which would fill up a 'traditional' power
law cluster mass function.Comment: 15 pages, 10 figures, accepted for publication in A&
Lichens as bioindicators of atmospheric heavy metal deposition in Valencia, Spain
The lichens due to their symbiotic nature have unique characteristics that confer them a
key role as bioindicators of the environmental contamination. Many investigations have been done using epiphytic lichens as bioindicators, but only a few of these studies have used epilithiccrustose lichens. Three different epilithic-crustose lichens species: Candelariella sp., Lecanora sp. and Caloplaca sp. were studied as bioindicators of V, Cr,Mn, Co, Ni, Cu, Zn, As, Rb, Sr,Mo, Cd, Sb, Ba, Pb, Bi and U trace elements. Inductively Coupled Plasma Mass Spectrometry routine procedure is used to determining these element concentrations. Two sites were selected for lichens sampling according to environmental contamination. The lichens were collected on the facade of
the Santos Juanes church in an urban area of Valencia; and on the rural area of Albarracin. The main aim of this work is showing the efficacy of the epilithic-crustose lichens as bioindicators of the air pollution. This study shows that the city of Valencia, compared with the rural area has high levels of Cu and Pb as detected using lichens as bioindicators. Therefore on the basis of these results, it can be hypothesized that Candelariella sp., Lecanora sp. and Caloplaca sp. are good accumulators of air borne heavy metals.This work has financial support of the Spanish Ministerio de Ciencia e Innovacion with a Ph.D. scholarship for Pilar Bosch Roig (BES-2006-12110) and with a three months stay scholarship to do this research in the Opificio delle Pietre Dure in Florence, Italy with Doctor Carlo Lalli. The authors wish to thank to the priest of the Santos Juanes Church of Valencia; the Direccion General de Patrimonio; to Prof. Pilar Roig Picazo and Prof. Ignacio Bosch Reig; the Instituto Universitario de Restauracion del Patrimonio from the Universitat Politecnica de Valencia; to the Ministero per I Beni Culturali; Italy.Bosch Roig, MDP.; Barca, D.; Crisci, G.; Lalli Galliano, C. (2013). Lichens as bioindicators of atmospheric heavy metal deposition in Valencia, Spain. Journal of Atmospheric Chemistry. 70(4):373-388. https://doi.org/10.1007/s10874-013-9273-6S373388704Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological profile for lead. Atlanta, GA.; 2007. http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=96&tid=22 . Accessed August 2010Ausset, P., Crovisier, J.L., Del Monte, M., Furlan, V., Girardet, F., Hammecker, C., Jeannette, D., Lefevre, A.: Experimental study of limestone and sandstone sulphation in polluted realistic conditions: the Lausanne Atmospheric Simulation Chamber (LASC). Atmos. Environ. 30, 3197–3207 (1996)Bajpai, D., Upreti, K., Dwivedi, S.K.: Arsenic accumulation in lichens of Mandav monuments, Dhar district, Madhya Pradesh, India. Environ. Monit. Assess. 159(1–4), 437–442 (2009)Bajpai, D., Upreti, K., Dwivedi, S.K.: Passive monitoring of atmospheric heavy metals in a historical city of central India by Lepraria lobificans Nyl. Environ. Monit. Assess. 166, 477–484 (2010)Barca, D., Belfiore, C.M., Crisci, G.M., La Russa, M.F., Pezzino, A., Ruffolo, S.A.: Application of laser ablation ICP-MS and traditional techniques to the study of black crusts on building stones: a new methodological approach. Environ. Sci. Pollut. Res. 17(8), 1433–1447 (2010)Barca, D., Belfiore, C.M., Crisci, G.M., La Russa, M.F., Pezzino, A., Ruffolo, S.A.: A new methodological approach for the chemical characterization of black crusts on building stones: a case study from the Catania city centre (Sicily, Italy). J. Anal. At. Spectrom. 26, 1000–1011 (2011)Bargagli-Pertrucci, G.: Studi sulla flora microscopia della regione boracifera della Toscana. La vegetazione cirittogamica nella regione boracifera. Giorn. Bot. Ital. 22, 409–411 (1915)Bates, J.W., Farmer, A.M.: Bryophytes and lichens in a changing environment. Oxford Science, Oxford (1992)Benco, C., Grillo, Rossi, E., Palmieri, F.: Biomonittoraggio di metalli mediante licheni epifi ti nel territorio della Spezia. Arpal, La Spezia (1989)Bretschneider, S., Marcano, V.: Utilización de lÃquenes como indicadores de contaminación por metales pesados y otros agentes en el Valle de Mérida. Rev. For. Venez. 1, 35–36 (1995)Brown, D.H., Beckett, R.P.: Differential sensitivity of lichens to heavy metals. Ann. Bot. 52, 51–57 (1983)Calatayud Lorente, V., Sanz Sánchez, M.J.: GuÃa de lÃquenes epifitos. Ministerio de medio ambiente. Organismo Autonomo parques nacionales, Spain (2000)Cardarelli, E., Achilli, M., Campanella, C., Bartoli, A.: Monitoraggio dell’inquinamento da metalli pesanti mediante l’uso di licheni nella città di Roma. Inquinamento 6, 56–63 (1993)Cicek, A., Koparal, A.S., Catak, S., Ugur, S.: The level of some heavy metals and nutritional elements in the samples from soils and trace levels growing in the vicinity of Syitomer thermal power plant in Kutahya (Turkey). In: Topcu, S. et al. (eds.) Air Quality Management at Urban, Regional and Global Scales, pp. 157–162. Istanbul, Turkey (2001)Cislaghi, C., Nimis, P.L.: Lichens, air polution and lung cancer. Nature 387, 463 (1997)Conti, M.E., Cecchetti, G.: Biological monitoring: lichens as bioindicators of air pollution assessment- a review. Environ. Pollut. 114, 471–492 (2001)Dakal, T.C., Cameotra, S.S.: Microbially induced deterioration of architectural heritages: routes and mechanisms involved. Environ. Sci. Eur. 24, 36–49 (2012)Déruelle, S.: La fiabilite des lichens comme bioindicateurs de la pollution plombique. Écologie 27, 285–290 (1996)Deschamps, E., Matschullat, J.: Arsenic: natural and anthropogenic. Arsenic in the environment, vol 4. CRC Press, Balkema (2011)Eggins, S.M., Woodhead, J.D., Kinsley, L.P.J., Mortimer, G.E., Sylvester, P., McCulloch, M.T., Hergt, J.M., Handler, M.R.: A simple method for the precise determination of 40 trace elements in geological samples by ICPMS using enriched isotope internal standardisation. Chem. Geol. 134, 311–326 (1997)Ferry, B.W., Baddeley, M.S., Hawksworth, D.L.: Air pollution and lichens. Athlone Press of the University of London, London (1973)Gabriele, B., Callegaretti, S.: Calidad del Aire. Bioacumulo de metales pesados en muestras liquénicas (Pseudevernia furfuracea) trasplantadas. The Patern (2005)Garty, J.: Biomonitoring atmospheric heavy metals with lichens: theory and application. Crit. Rev. Plant Sci. 20(4), 309–371 (2001)Garty, J., Galun, M., Hochberg, Y.: The accumulation of metals in Caloplaca aurantia growing on concrete roof tiles. Lichenologist 18, 257–263 (1986)Garty, J., Fuchs, C., Zisapel, N., Galun, M.: Heavy metals in the lichen Caloplaca aurantia from urban, suburban and rural regions in Israel (a comparative study). Water Air Soil Pollut. 8, 171–188 (1977)Ghirardi, R., Fosco, M.E., Gervasio, S.G., Imbert, D., Enrique, C., Pacheco, C.G.: LÃquenes y claveles del aire como bioindicadores de contaminación atmosférica por metales pesados en el microcentro santafesino. Fabicib 14, 165–173 (2010)Gordon, C.A., Herrera, R., Hutchinson, T.C.: The use of a common epiphytic lichen as a bioindicator of atmospheric inputs to two Venezuelan cloud forests. J. Trop. Ecol. 11, 1–26 (1996)Grossi, G.M., Esbert, R.M., Diaz-Pache, F., Alonso, F.J.: Soiling of building stones in urban environments. Build. Environ. 38, 147–159 (2003)Hale, M.E.J.R., Lawrey, J.: D.: Annual rate of lead accumulation in the lichen Pseudoparmelia baltimorensis. Bryologist 88, 5–7 (1985)Hawksworth, D.L., MCManus, P.M.: Lichen recolonization in London under conditions of rapidly falling sulphur dioxide and the concept of zone skipping. Bot. J. Linn. Soc. 100, 99 (1989)Hawksworth, D.L.: In: Woodwell, G.M. (ed.) The earth in transition: patterns and processes of biotic impoverishment. Cambridge University Press, Cambridge (1990)Hawksworth, D.L., Iturriaga, T., Crespo, A.: Rev. LÃquenes como bioindicadores inmediatos de contaminación y cambios medio-ambientales en los trópicos. Rev. Iberoam. Micol. 22, 71–82 (2005)ICOMOS-ISCS: Illustrated glossary on stone deterioration patterns. Ateliers 30, Champigny/Marne, France V. Vergès-Belmin (eds). (2008)Kircher, G., Daillant, Q.: The potential of lichens as long term bioindicators of natural and artificial radionuclides. Environ. Pollut. 120, 145–150 (2002)Kularatne, K.I.A., de Freitas, C.R.: Epiphytic lichens as biomonitors of airborne heavy metal pollution. Environ. Exp. Bot. 88, 24–32 (2013). doi: 10.1016/j.envexpbot.2012.02.010Lawrey, J.D.: Lichens as monitors of pollutant elements at permanent sites in Maryland and Virginia. Bryologist 96, 339–341 (1993)Leone, N., Courbon, D., Ducimetiere, P., Zureik, M.: Zinc, copper, and magnesium and risks for all-cause, cancer, and cardiovascular mortality. Epidemiology 17(3), 308–314 (2006)Loppi, S., Pacioni, G., Olivieri, N., Digiacomo, F.: Accumulation of trace-metals in the lichen evernia-prunastri transplanted at biomonitoring sites in central Italy. Bryologist 101(3), 451–454 (1998)Mangiafico, R., Pitruzzello, P.: Biomonitoraggio della qualità dell’aria nell’area comunale di augusta tramite licheni come bioaccumulatori. Not. Soc. Lich. Ital. 15, 49–50 (2002)Miani, N., Skert, N., Grahonja, R.: Atlante dei licheni epifiti piu’ comuni rinvenuti in studi di biomonitaraggio ambientale nella provincia di Trieste. ARPA FVG Dipartimento di Trieste (eds). Provincia diTrieste, Italy (2006)Monaci, F., Bargagli, R., Gasparo, D.: Air pollution monitoring by lichens in a small medieval town of central Italy. Acta Bot. Neerlandica 46, 403–412 (1997)Nieboer, E., Richardson, D.H.S., Tomassini, F.D.: Mineral uptake and release by lichens: an overview. Bryologist 81(2), 226–246 (1978)Nimis, P.L., Scheidegger, C., Wolseley, P.: Monitoring with lichens-monitoring lichens. NATO Science Series IV, Earth and Environmental Science vol 7. Kluwer Academic Publishers, Dordrecht (2002)Nimis, P.L., Castello, M., Perotti, M.: Lichens as biomonitors of sulphur di oxide pollution in La Spezia (north Italy). Lichenologist 22, 333–344 (1990)Nylander, W.: Les lichens du Jardin du Luxembourg. Bull. Soc. Bot. 13, 364–372 (1866)Palmieri, F., Neri, R., Benco, C., Serracca, L.: Lichens and moss as bioindicators and bioaccumulators in air pollution monitoring. J. Environ. Pathol. Toxicol. Oncol. 16, 175–190 (1997)Purvis, O.W.: Interactions of lichens with metals. Sci. Prog. 79, 283–309 (1996)Quijada H., Ph.: Implementación de lÃquenes como biomonitores de contaminación por metales pesados (Pb, Cu, Zn, Cd, Ni), en la ciudad de Caracas, Venezuela. Caracas, Venezuela (2006)Riccardi, N., Leone, A., Barbati, S., Aprile, G.G., Menna. A.: Risultati preliminari di un programma di monitoraggio in un sito ad alto rischio (Comune di Acerra - Napoli). Not. Soc. Lich. Ital. Poster. (2001)Richardson, D.H.S.: Pollution monitoring with lichens. Richmond Publishing, Slough (1992)RodrÃguez-Navarro, C., Sebastian, E.: Sci. Total Environ. 187, 79 (1996)Rossbach, M., Jayasekera, R., Kniewald, G., Thang-Nguyen, H.: Large scale air monitoring: lichen vs. air particulate matter analysis. Sci. Total Environ. 232(1–2), 59–66 (1999)Rossbach, M., Lambrecht, S.: Lichens as biomonitors: global, regional and local aspects. Croat. Chem. Acta 79(1), 119–124 (2006)Seaward, M.R.D.: Performance of Lecanora muralis in an urban environment. In: Brown, D.H., Hawksworth, D.L., Bailey, R.H. (eds.) Lichenology: progress and problems. Academic, London (1976)Showman, R.E.: Lichen recolonization in the Upper Ohio River Valley. Bryologist 93(4), 427–428 (1990)Stork, N.E., Sanways, M.J.: Inventoring and monitoring of biodiversity. In: Heywood, V.H. (ed.) Global biodiversity assessment, pp. 453–543. Cambridge University Press, Cambridge (1995)Temina, M.: Growth of lichens on limestone outcrops in northern Estonia. IAL 3 – Proceedings. Sauteria, 173–180 (1998)Tingey, D.T.: Bioindicators in air pollution research—applications and constraints. In: Biological markers of air pollution stress and damage in forests. National Research Council, National Academy Press, Washington, D.C. (1989)Valencia’s city council traffic information: Plano de Intensidades de trafico dÃas laborables 2012 Ayuntamiento de Valencia. Servei de transports i curculació, Valencia, Spain (2012) http://www.valencia.es/ayuntamiento/trafico.nsf/ . Accessed August 2013Warscheid, T., Braams, J.: Biodeterioration of stone: a review. Int. Biodeterior. Biodegrad. 46, 343–368 (2000)Winkler, M.E.: Stone in architecture, properties, durability, 3rd edn. Springer, Berlin (1997)World Health Organization. Air quality guidelines (2nd Ed). Denmark (2001)Zschau, T., Getty, S., Gries, C., Ameron, Y., Zambrano, A., Nash, T.H.: Historical and current atmospheric deposition to the epilithic lichen Xanthoparmelia in Maricopa County, Arizona. Environ. Pollut. 125, 21–30 (2003
Physical conditions in the gas phases of the giant HII region LMC-N11 unveiled by Herschel - I. Diffuse [CII] and [OIII] emission in LMC-N11B
(Abridged) The Magellanic Clouds provide a nearby laboratory for metal-poor
dwarf galaxies. The low dust abundance enhances the penetration of UV photons
into the interstellar medium (ISM), resulting in a relatively larger filling
factor of the ionized gas. Furthermore, there is likely a hidden molecular gas
reservoir probed by the [CII]157um line. We present Herschel/PACS maps in
several tracers, [CII], [OI]63um,145um, [NII]122um, [NIII]57um, and [OIII]88um
in the HII region N11B in the Large Magellanic Cloud. Halpha and [OIII]5007A
images were used as complementary data to investigate the effect of dust
extinction. Observations were interpreted with photoionization models to infer
the gas conditions and estimate the ionized gas contribution to the [CII]
emission. Photodissociation regions (PDRs) are probed through polycyclic
aromatic hydrocarbons (PAHs). We first study the distribution and properties of
the ionized gas. We then constrain the origin of [CII]157um by comparing to
tracers of the low-excitation ionized gas and of PDRs. [OIII] is dominated by
extended emission from the high-excitation diffuse ionized gas; it is the
brightest far-infrared line, ~4 times brighter than [CII]. The extent of the
[OIII] emission suggests that the medium is rather fragmented, allowing far-UV
photons to permeate into the ISM to scales of >30pc. Furthermore, by comparing
[CII] with [NII], we find that 95% of [CII] arises in PDRs, except toward the
stellar cluster for which as much as 15% could arise in the ionized gas. We
find a remarkable correlation between [CII]+[OI] and PAH emission, with [CII]
dominating the cooling in diffuse PDRs and [OI] dominating in the densest PDRs.
The combination of [CII] and [OI] provides a proxy for the total gas cooling in
PDRs. Our results suggest that PAH emission describes better the PDR gas
heating as compared to the total infrared emission.Comment: Accepted for publication in Astronomy and Astrophysics. Fixed
inverted line ratio in Sect. 5.
A milestone toward understanding PDR properties in the extreme environment of LMC-30Dor
More complete knowledge of galaxy evolution requires understanding the
process of star formation and interaction between the interstellar radiation
field and the interstellar medium in galactic environments traversing a wide
range of physical parameter space. Here we focus on the impact of massive star
formation on the surrounding low metallicity ISM in 30 Doradus in the Large
Magellanic Cloud. A low metal abundance, as is the case of some galaxies of the
early universe, results in less ultra-violet shielding for the formation of the
molecular gas necessary for star formation to proceed. The half-solar
metallicity gas in this region is strongly irradiated by the super star cluster
R136, making it an ideal laboratory to study the structure of the ISM in an
extreme environment. Our spatially resolved study investigates the gas heating
and cooling mechanisms, particularly in the photo-dissociation regions where
the chemistry and thermal balance are regulated by far-ultraviolet photons (6
eV< h\nu <13.6 eV).
We present Herschel observations of far-infrared fine-structure lines
obtained with PACS and SPIRE/FTS. We have combined atomic fine-structure lines
from Herschel and Spitzer observations with ground-based CO data to provide
diagnostics on the properties and the structure of the gas by modeling it with
the Meudon PDR code. We derive the spatial distribution of the radiation field,
the pressure, the size, and the filling factor of the photodissociated gas and
molecular clouds. We find a range of pressure of ~ 10^5 - 1.7x10^6 cm^{-3} K
and a range of incident radiation field G_UV ~ 10^2 - 2.5x10^4 through PDR
modeling. Assuming a plane-parallel geometry and a uniform medium, we find a
total extinction of 1-3 mag , which correspond to a PDR cloud size of 0.2 to
3pc, with small CO depth scale of 0.06 to 0.5pc. We also determine the three
dimensional structure of the gas. (Abridged)Comment: 20 pages, 23 figures, accepted in A&
The effects of star formation on the low-metallicity ISM: NGC4214 mapped with Herschel/PACS spectroscopy
We present Herschel/PACS spectroscopic maps of the dwarf galaxy NC4214
observed in 6 far infrared fine-structure lines: [C II] 158mu, [O III] 88mu, [O
I] 63mu, [O I] 146mu, [N II] 122mu, and [N II] 205mu. The maps are sampled to
the full telescope spatial resolution and reveal unprecedented detail on ~ 150
pc size scales. We detect [C II] emission over the whole mapped area, [O III]
being the most luminous FIR line. The ratio of [O III]/[C II] peaks at about 2
toward the sites of massive star formation, higher than ratios seen in dusty
starburst galaxies. The [C II]/CO ratios are 20 000 to 70 000 toward the 2
massive clusters, which are at least an order of magnitude larger than spiral
or dusty starbursts, and cannot be reconciled with single-slab PDR models.
Toward the 2 massive star-forming regions, we find that L[CII] is 0.5 to 0.8%
of the LTIR . All of the lines together contribute up to 2% of LTIR . These
extreme findings are a consequence of the lower metallicity and young,
massive-star formation commonly found in dwarf galaxies. These conditions
promote large-scale photodissociation into the molecular reservoir, which is
evident in the FIR line ratios. This illustrates the necessity to move to
multiphase models applicable to star-forming clusters or galaxies as a whole.Comment: Accepted for publication in the A&A Herschel Special Issu
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