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Titolo:
ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster
Autore:
Bontemps, S; Andre, P; Kaas, AA; Nordh, L; Olofsson, G; Huldtgren, M; Abergel, A; Blommaert, J; Boulanger, F; Burgdorf, M; Cesarsky, CJ; Cesarsky, D; Copet, E; Davies, J; Falgarone, E; Lagache, G; Montmerle, T; Perault, M; Persi, P; Prusti, T; Puget, JL; Sibille, F;
Indirizzi:
Observ Bordeaux, F-33270 Florac, France Observ Bordeaux Florac France F-33270 v Bordeaux, F-33270 Florac, France Stockholm Observ, S-13336 Saltsjobaden, Sweden Stockholm Observ Saltsjobaden Sweden S-13336 -13336 Saltsjobaden, Sweden CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette, France CEA Saclay GifSur Yvette France F-91191 F-91191 Gif Sur Yvette, France ESA, ESTEC, Div Astrophys, Amsterdam, Netherlands ESA Amsterdam Netherlands ESTEC, Div Astrophys, Amsterdam, Netherlands Univ Paris 11, IAS, F-91405 Orsay, France Univ Paris 11 Orsay France F-91405 Paris 11, IAS, F-91405 Orsay, France ESA, Div Astrophys, ISO, SOC, Villafranca, Spain ESA Villafranca SpainESA, Div Astrophys, ISO, SOC, Villafranca, Spain Observ Paris Meudon, DESPA, F-92195 Meudon, France Observ Paris Meudon Meudon France F-92195 DESPA, F-92195 Meudon, France Joint Astron Ctr, Hilo, HI 96720 USA Joint Astron Ctr Hilo HI USA 96720Joint Astron Ctr, Hilo, HI 96720 USA ENS Radioastron, F-75231 Paris, France ENS Radioastron Paris France F-75231 Radioastron, F-75231 Paris, France CNR, IAS, Area Ric Tor Vergata, I-00133 Rome, Italy CNR Rome Italy I-00133 R, IAS, Area Ric Tor Vergata, I-00133 Rome, Italy Observ Lyon, F-69230 St Genis Laval, France Observ Lyon St Genis Laval France F-69230 F-69230 St Genis Laval, France
Titolo Testata:
ASTRONOMY & ASTROPHYSICS
fascicolo: 1, volume: 372, anno: 2001,
pagine: 173 - 194
SICI:
1432-0746(200106)372:1<173:IOOTRO>2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Soggetto:
YOUNG STELLAR OBJECTS; T-TAURI STARS; RHO-OPHIUCHI; DARK CLOUD; CIRCUMSTELLAR MATERIAL; INFRARED OBSERVATIONS; EVOLUTIONARY STATUS; SOLAR NEIGHBORHOOD; OB ASSOCIATION; EXTINCTION LAW;
Keywords:
stars : formation; stars : low-mass, brown dwarfs; stars : luminosity function, mass function; stars : pre-main sequence; ISM : individual objects : p Ophiuchi cloud;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
90
Recensione:
Indirizzi per estratti:
Indirizzo: Bontemps, S Observ Bordeaux, BP 89, F-33270 Florac, France Observ BordeauxBP 89 Florac France F-33270 70 Florac, France
Citazione:
S. Bontemps et al., "ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster", ASTRON ASTR, 372(1), 2001, pp. 173-194

Abstract

We present the results of the first extensive mid-infrared (IR) imaging survey of the rho Ophiuchi embedded cluster, performed with the ISOCAM cameraon board the ISO satellite. The main rho Ophiuchi molecular cloud L1688, as well as the two secondary clouds L1689N and L1689S, have been completely surveyed for point sources at 6.7 mum and 14.3 mum. A total of 425 sources are detected in similar to0.7 deg(2), including 16 Class I, 123 Class II, and 77 Class III young stellar objects (YSOs). Essentially all of the mid-IRsources coincide with near-IR sources, but a large proportion of them are recognized for the first time as YSOs. Our dual-wavelength survey allows usto identify essentially all the YSOs with IR excess in the embedded cluster down to F-v similar to 10-15 mJy. It more than doubles the known population of Class II YSOs and represents the most complete census to date of newly formed stars in the rho Ophiuchi central region. There are, however, reasons to believe that several tens of Class III YSOs remain to be identified below L-* similar to 0.2 L-circle dot. The mid-IR luminosities of most (similar to 65%) Class II objects are consistent with emission from purely passive circumstellar disks. The stellar luminosity function of the complete sample of Class II YSOs is derived with good accuracy down to L-* similar to 0.03 L-circle dot. It is basically at (in logarithmic units) below L-* similar to 0.2 L-circle dot, exhibits a possible local maximum at L-* similar to 1.5 L-circle dot, and sharply falls off at higher luminosities. A modeling of the luminosity function, using available pre-main sequence tracks and plausible star formation histories, allows us to derive the mass distribution of the Class II YSOs which arguably reflects the initial mass function (IMF) of the embedded cluster. After correction for the presence of unresolved binary systems, we estimate that the IMF in rho Ophiuchi is well described by a two-component power law with a low-mass index of -0.35 +/- 0.25, a high-mass index of 1.7 (to be compared with the Salpeter value of -1.35), and a break occurring at M-flat = 0.55 +/- 0.25 M-circle dot. This IMF is atwith no evidence for a low-mass cutoff down to at least similar to0.06 M-circle dot.

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Documento generato il 04/04/20 alle ore 14:42:58