ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster

By S. Bontemps, P. Andre', A. A. Kaas, L. Nordh, G. Olofsson, M. Huldtgren, Alain Abergel, J. Blommaert, F. Boulanger, M. Burgdorf and 14 more. 2001

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We present the results of the first extensive mid-infrared (IR) imaging survey of the rho Ophiuchi embedded cluster, performed with the ISOCAM camera on board the ISO satellite. The main molecular cloud L1688, as well as L1689N and L1689S, have been completely surveyed for point sources at 6.7 and 14.3 micron. A total of 425 sources are detected including 16 Class I, 123 Class II, and 77 Class III young stellar objects (YSOs). Essentially all of the mid-IR sources coincide with near-IR sources, but a large proportion of them are recognized for the first time as YSOs. Our dual-wavelength survey allows us to identify essentially all the YSOs with IR excess in the embedded cluster down to Fnu ~ 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. The stellar luminosity function of the complete sample of Class II YSOs is derived with a good accuracy down to L= 0.03 Lsun. A modeling of this lumino- sity function, using available pre-main sequence tracks and plausible star for- mation histories, allows us to derive the mass distribution of the Class II YSOs which arguably reflects the IMF of the embedded cluster. 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 = 0.55+/-0.25 Msun. This IMF is flat with no evidence for a low-mass cutoff down to at least 0.06 Msun.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0002ef802315c0bcf12ec927e88ba6c8809c0ff3

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Citations in the corpus

Stellar, brown dwarf and multiple star properties from hydrodynamical simulations of star cluster formation (2008, background): “By contrast, the ρ Ophiuchi cloud contains a similar mass of stars and gas to the calculations presented here (Bontemps et al. 2001), but it is composed of many sub-clusters rather than a single large cluster.”
Magnetic fields and accretion flows on the classical T Tauri star V2129 Oph (2007, background): “Although V2129 Oph was too faint to be observed with Hipparcos (and thus to have its parallax estimated accurately), its membership of the ρ Oph dark cloud indicates that its distance is about 140 ± 10 pc (Bontemps et al. 2001).”
On the mass function of star clusters (2002, background): “Members of this class are the embedded clusters in Orion cloud L1630 (Lada & Lada 1991) and the embedded cluster ρ Oph (Bontemps et al. 2001).”
Optical Spectroscopy of the Surface Population of the ρ Ophiuchi Molecular Cloud: The First Wave of Star Formation (2005, methodology): “Excess emission at K ( r k ¼ 0 : 34) and in the mid-infrared (Bontemps et al. 2001) are indicative of a circumstellar disk (Natta et al. 2002).”
From molecular cores to planet-forming disks: An SIRTF legacy program (2003, background): “A large list of Class 0, I, and II sources was compiled, primarily from the existing near- and mid-infrared surveys of the mapped clouds (Persi et al. 2000; Bontemps et al. 2001).”
YOUNG STELLAR OBJECTS IN THE GOULD BELT (2015, background): “While ISO surveys identified many new deeply embedded and low luminosity YSOs, they only focused on small portions of molecular clouds (e.g., Bontemps et al. 2001; Persi et al. 2003; Kaas et al. 2004).”
The initial conditions of star formation in the Ophiuchus main cloud: Kinematics of the protocluster condensations , (2007, methodology): “These Ophiuchus condensations, which were identified using a multi-resolution analysis equivalent to a wavelet decomposition (cf. Starck et al. 1998; Motte et al. 2003), are seenon the same spatial scales as protostellar envelopes (i.e., ∼ 2300–4500 AU or∼ 15′′−30′′ in L1688).”
A 3-5 mu m VLT spectroscopic survey of embedded young low mass stars I - Structure of the CO ice (2003, background): “The sample inludes class I sources as well as flat spectrum sources defined by having a vanishing spectral index between 2.5 and 15µm (Bontemps et al. 2001).”
Embedded Clusters in Molecular Clouds (2003, background): “Examples 31 Jul 2003 21:33 AR AR194-AA41-03.tex AR194-AA41-03.sgm LaTeX2e(2002/01/18) P1: GJB 98 LADA ¥ LADA of embedded clusters that are protostar rich include NGC 1333, Serpens, and Rho Ophiuchi.”
Fragmentation and mass segregation in the massive dense cores of Cygnus X (2009, background): “On the other hand, the global star formation efficiency (hereafter SFE), which includes also the masses of the already formed stars, is on average more of the order of 30% (Bontemps et al. 2001) at the scale of the dense cores in the ρ Ophiuchi proto-cluster.”
Spectroscopy of polycyclic aromatic hydrocarbons and very small grains in photodissociation regions (2005, background): “The PDR studied in the present paper is located in the main ρ Oph cloud L1688 at a distance of about 140 pc and results from the illumination of the molecular cloud by a bright embedded young star, SR3 of spectral type B7 (Bontemps et al. 2001).”
Inverse dynamical population synthesis: Constraining the initial conditions of young stellar clusters by studying their binary populations (2012, result): “Bontemps et al. (2001) find, after correcting for an assumed binary fraction of 75 percent, a stellar mass-function for young stellar objects (YSOs) that is consistent with the slope of the canonical stellar IMF for low masses (0.055− 0.55M⊙) and agrees with earlier (Comeron et al. 1993; Strom et…”
THE SPITZER c2d LEGACY RESULTS: STAR-FORMATION RATES AND EFFICIENCIES; EVOLUTION AND LIFETIMES (2008, methodology): “Some of these clouds were targets of ISO surveys of smaller regions: 0.7 sq. deg. in Ophiuchus (Bontemps et al. 2001); 0.13 sq. deg. in Serpens (Kaas et al. 2004); and 0.2 sq. deg. in Cha II (Persi et al. 2003).”