Abergel, A;Ade, PAR;Aghanim, N;Arnaud, M;Ashdown, M;Aumont, J;Baccigalupi, C;Balbi, A;Banday, AJ;Barreiro, RB;Bartlett, JG;Battaner, E;Benabed, K;Benoit, A;Bernard, JP;Bersanelli, M;Bhatia, R;Bock, JJ;Bonaldi, A;Bond, JR;Borrill, J;Bouchet, FR;Boulanger, F;Bucher, M;Burigana, C;Cabella, P;Cardoso, JF;Catalano, A;Cayon, L;Challinor, A;Chamballu, A;Chiang, LY;Chiang, C;Christensen, PR;Clements, DL;Colombi, S;Couchot, F;Coulais, A;Crill, BP;Cuttaia, F;Danese, L;Davies, RD;Davis, RJ;de Bernardis, P;de Gasperis, G;de Rosa, A;de Zotti, G;Delabrouille, J;Delouis, JM;Desert, FX;Dickinson, C;Dobashi, K;Donzelli, S;Dore, O;Dorl, U;Douspis, M;Dupac, X;Efstathiou, G;Ensslin, TA;Eriksen, HK;Finelli, F;Forni, O;Frailis, M;Franceschi, E;Galeotta, S;Ganga, K;Giard, M;Giardino, G;Giraud-Heraud, Y;Gonzalez-Nuevo, J;Gorski, KM;Gratton, S;Gregorio, A;Gruppuso, A;Guillet, V;Hansen, FK;Harrison, D;Henrot-Versille, S;Herranz, D;Hildebrandt, SR;Hivon, E;Hobson, M;Holmes, WA;Hovest, W;Hoyland, RJ;Huffenberger, KM;Jaffe, AH;Jones, A;Jones, WC;Juvela, M;Keihanen, E;Keskitalo, R;Kisner, TS;Kneissl, R;Knox, L;Kurki-Suonio, H;Lagache, G;Lamarre, JM;Lasenby, A;Laureijs, RJ;Lawrence, CR;Leach, S;Leonardi, R;Leroy, C;Linden-Vornle, M;Lopez-Caniego, M;Lubin, PM;Macias-Perez, JF;MacTavish, CJ;Maffei, B;Mandolesi, N;Mann, R;Maris, M;Marshall, DJ;Martin, P;Martinez-Gonzalez, E;Masi, S;Matarrese, S;Matthai, F;Mazzotta, P;McGehee, P;Meinhold, PR;Melchiorri, A;Mendes, L;Mennella, A;Mitra, S;Miville-Deschenes, MA;Moneti, A;Montier, L;Morgante, G;Mortlock, D;Munshi, D;Murphy, A;Naselsky, P;Natoli, P;Netterfield, CB;Norgaard-Nielsen, HU;Noviello, F;Novikov, D;Novikov, I;Osborne, S;Pajot, F;Paladini, R;Pasian, F;Patanchon, G;Perdereau, O;Perotto, L;Perrotta, F;Piacentini, F;Piat, M;Plaszczynski, S;Pointecouteau, E;Polenta, G;Ponthieu, N;Poutanen, T;Prezeau, G;Prunet, S;Puget, JL;Reach, WT;Rebolo, R;Reinecke, M;Renault, C;Ricciardi, S;Riller, T;Ristorcelli, I;Rocha, G;Rosset, C;Rubino-Martin, JA;Rusholme, B;Sandri, M;Santos, D;Savini, G;Scott, D;Seiffert, MD;Shellard, P;Smoot, GF;Starck, JL;Stivoli, F;Stolyarov, V;Sudiwala, R;Sygnet, JF;Tauber, JA;Terenzi, L;Toffolatti, L;Tomasi, M;Torre, JP;Tristram, M;Tuovinen, J;Umana, G;Valenziano, L;Verstraete, L;Vielva, P;Villa, F;Vittorio, N;Wade, LA;Wandelt, BD;Yvon, D;Zacchei, A;Zonca, A

2011

December

Astronomy and Astrophysics

Planck early results. XXV. Thermal dust in nearby molecular clouds

Published

118 ()

PRE-LAUNCH STATUS OPTICAL-PROPERTIES INTERSTELLAR DUST SPECTRAL INDEX TEMPERATURE-DEPENDENCE INFRARED OBSERVATIONS PHYSICAL-PROPERTIES INITIAL HIGHLIGHTS GALACTIC PLANE COLD DUST

536

Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic residuals are detected at 353 GHz and 143 GHz, with amplitudes around -7% and +13%, respectively, indicating that the measured spectra are likely more complex than a simple modified blackbody. Significant positive residuals are also detected in the molecular regions and in the 217 GHz and 100 GHz bands, mainly caused by the contribution of the J = 2 -> 1 and J = 1 -> 0 (CO)-C-12 and (CO)-C-13 emission lines. We derive maps of the dust temperature T, the dust spectral emissivity index beta, and the dust optical depth at 250 mu m tau(250). The temperature map illustrates the cooling of the dust particles in thermal equilibrium with the incident radiation field, from 16-17 K in the diffuse regions to 13-14 K in the dense parts. The distribution of spectral indices is centred at 1.78, with a standard deviation of 0.08 and a systematic error of 0.07. We detect a significant T - beta anti-correlation. The dust optical depth map reveals the spatial distribution of the column density of the molecular complex from the densest molecular regions to the faint diffuse regions. We use near-infrared extinction and Hi data at 21-cm to perform a quantitative analysis of the spatial variations of the measured dust optical depth at 250 mu m per hydrogen atom tau(250)/N-H. We report an increase of tau(250)/N-H by a factor of about 2 between the atomic phase and the molecular phase, which has a strong impact on the equilibrium temperature of the dust particles.

LES ULIS CEDEX A

0004-6361

10.1051/0004-6361/201116483