A Near‐Infrared Imaging Survey of the ρ Ophiuchi Cloud Core

Barsony, M.; Kenyon, Scott J.; Lada, Elizabeth A.; Teuben, Peter

doi:10.1086/313029

Cited by 113 publications

(184 citation statements)

References 24 publications

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“…(Class II and III objects) in Ophiuchus that were detected in the vicinity of our target protostars. Objects whose name starts with "B" are from Barsony et al (1997). The classification is determined from the infrared spectral indices following Bontemps et al (2001).…”

Section: Discussionmentioning

confidence: 99%

“…With all three J, H and K filters, we obtained a sequence of 10 × 1.18 s exposures using a random jittering pattern in a 20 × 20 box. Bontemps et al (2001), while the near-infrared magnitudes are from Barsony et al (1997), Greene et al (1994) and the 2MASS database (2MASS uses a Ks filter rather than a K filter; the difference in magnitude for an object can reach a few tenths of a magnitude). The source marked with a † symbol has an infrared spectral index typical of a normal Class II source but Ressler & Barsony (2001) have shown that this system contains a Class I source and it is classified as such here.…”

Section: Sample Selection and Observationsmentioning

confidence: 99%

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Multiple protostellar systems

Duchêne

Bouvier²,

Bontemps

et al. 2004

A&A

112

147

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Abstract. We performed a deep infrared imaging survey of 63 embedded young stellar objects (YSOs) located in the Taurus and Ophiuchus clouds to search for companions. The sample includes Class I and flat infrared spectrum protostellar objects. We find 17 companions physically bound to 15 YSOs with angular separations in the range 0.8-10 (110-1400 AU) and derive a companion star fraction of 23 ± 9% and 29 ± 7% for embedded YSOs in Taurus and Ophiuchus, respectively, about twice as large as that found among G dwarfs in the solar neighborhood. Therefore, binary and multiple protostellar systems are a very frequent outcome of the fragmentation of prestellar cores. In spite of different properties of the clouds and especially of the prestellar cores, the fraction of wide companions, 27 ± 6% for the combined sample, is identical in the two star-forming regions. This suggests that the frequency and properties of wide multiple protostellar systems are not very sensitive to specific initial conditions. Comparing the companion star fraction of the youngest YSOs still surrounded by extended envelopes to that of more evolved YSOs, we find evidence for a possible evolution of the fraction of wide multiple systems, which seems to decrease by a factor of about two on a timescale of ∼10 5 yr. For the first time it is possible to confront the result of a multiplicity survey of a nearly complete population of embedded YSOs at an age of ∼10 5 yr to numerical simulations of molecular cloud collapse which, after a few free fall times, reach this evolutionary stage. Somewhat contrary to model predictions, we do not find evidence for a sub-clustering of embedded sources at this stage on a scale of a few 100 AU that could be related to the formation of small-N protostellar clusters. Possible interpretations of this discrepancy are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Sample Selection and Observationsmentioning

confidence: 99%

Multiple protostellar systems

Duchêne

Bouvier²,

Bontemps

et al. 2004

A&A

112

147

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“…There is no indication of Hα emission in the optical spectrum, which could support the scenario where the YSO is at its rest accretion state. We have compiled the available IR measurements from the literature, which are described in the following articles: Barsony et al (1997 , where uncertainties are typically < ∼ 0.1 mag. The magnitudes have not been corrected to a unique photometric system, though this cannot account for the large variations that can only be explained by intrinsic variability.…”

Section: Membershipmentioning

confidence: 99%

Spectroscopy of new brown dwarf members ofρ Ophiuchi and an updated initial mass function

Oliveira¹,

Moraux²,

Bouvier³

et al. 2012

A&A

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Aims. To investigate the universality hypothesis of the initial mass function in the substellar regime, the population of the ρ Ophiuchi molecular cloud is analysed by including a new sample of low-mass spectroscopically confirmed members. To that end, we have conducted a large spectroscopic follow-up of young substellar candidates uncovered in our previous photometric survey. Methods. The spectral types and extinction were derived for a newly found population of substellar objects, and its masses estimated by comparison to evolutionary models. A thoroughly literature search was conducted to provide an up-to-date census of the cluster, which was then used to derive the luminosity and mass functions, as well as the ratio of brown dwarfs to stars in the cluster. These results were then compared to other young clusters. Results. It is shown that the study of the substellar population of the ρ Ophiuchi molecular cloud is hampered only by the high extinction in the cluster ruling out an apparent paucity of brown dwarfs. The discovery of 16 new members of ρ Ophiuchi, 13 of them in the substellar regime, reveals the low-mass end of its population and shows the success of our photometric candidate selection with the WIRCam survey. The study of the brown dwarf population of the cluster reveals a high disk fraction of 76 +5 −8 %. Conclusions. Taking the characteristic peak mass of the derived mass function and the ratio of brown dwarfs to stars into account, we conclude that the mass function of ρ Ophiuchi is similar to other nearby young clusters.

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“…Luhman et al 1997. For the latter, the near-simultaneous photometry of Barsony et al 1997 has been adopted).…”

Section: Emission-line Spectrummentioning

confidence: 99%

Intense accretion and mass loss of a very low mass young stellar object

Fernández

Comerón²

2001

A&A

126

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Abstract. We present visible and near-infrared photometry and spectroscopy of LS-RCrA 1, a faint, very late-type object (M 6.5-M 7) seen in the direction of the R Coronae Australis star forming complex. While its emission spectrum shows prominent features of accretion and mass loss typical of young stellar objects, its underlying continuum and photometric properties are puzzling when trying to derive a mass and age based on pre-main sequence evolutionary tracks: the object appears to be far too faint for a young member of the R Coronae Australis complex of its spectral type. We speculate that this may be due to either its evolution along pre-main sequence tracks being substantially altered by the intense accretion, or to a combination of partial blocking and scattering of the light of the object by a nearly edge-on circumstellar disk. The rich emission line spectrum superimposed on the stellar continuum is well explained by an intense accretion process: the Hα, CaII infrared triplet, and HeI 6678 lines show equivalent widths typical of very active classical T Tauri stars. The near-infrared observations show anomalously weak spectral features and no significant excess emission in the K band, which we tentatively interpret as indicating line filling due to emission in a magnetic accretion funnel flow. At the same time, numerous, strong forbidden optical lines ([OI], [NII] and [SII]) and H2 emission at 2.12 µm suggest that the object is simultaneously undergoing mass loss, providing another example that shows that mass loss and accretion are closely related processes. Such an intense accretion and mass loss activity is observed for the first time in a young stellar object in the transition region between low mass stars and brown dwarfs, and provides a valuable observational test on the effects of accretion on the evolution of objects with such low masses.

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A Near‐Infrared Imaging Survey of the ρ Ophiuchi Cloud Core

Cited by 113 publications

References 24 publications

Multiple protostellar systems

Multiple protostellar systems

Spectroscopy of new brown dwarf members ofρ Ophiuchi and an updated initial mass function

Intense accretion and mass loss of a very low mass young stellar object

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