Astrophysics of Young Star Binaries

Prato, L.; Greene, Thomas P.; Simon, M.

doi:10.1086/345828

Cited by 142 publications

(227 citation statements)

References 75 publications

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“…The SED that results from our best model for AS 205 N differs by about 40% from the photometric measurements of Prato et al (2003) in the NIR wavelength range (Fig. 2).…”

Section: As 205 Nmentioning

confidence: 56%

“…There are previous flux measurements in the NIR and MIR wavelength ranges that can be exclusively ascribed to the northern component (Eisner et al 2005;Prato et al 2003). Apart from a recent observation at a wavelength of 860 μm (Andrews et al (2011), we assumed that all other previous photometric measurements could not spatially resolve each single component of the system.…”

Section: As 205 Nmentioning

confidence: 99%

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Multiwavelength interferometric observations and modeling of circumstellar disks

Schegerer

Ratzka

Schuller

et al. 2013

A&A

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Aims. We investigate the structure of the innermost region of three circumstellar disks around pre-main sequence stars HD 142666, AS 205 N, and AS 205 S. We determine the inner radii of the dust disks and, in particular, search for transition objects where dust has been depleted and inner disk gaps have formed at radii of a few tenths of AU up to several AU. Methods. We performed interferometric observations with IOTA, AMBER, and MIDI in the infrared wavelength ranges 1.6−2.5 μm and 8−13 μm with projected baseline lengths between 25 m and 102 m. The data analysis was based on radiative transfer simulations in 3D models of young stellar objects (YSOs) to reproduce the spectral energy distribution and the interferometric visibilities simultaneously. Accretion effects and disk gaps could be considered in the modeling approach. Results from previous studies restricted the parameter space. Results. The objects of this study were spatially resolved in the infrared wavelength range using the interferometers. Based on these observations, a disk gap could be found for the source HD 142666 that classifies it as transition object. There is a disk hole up to a radius of R in = 0.30 AU and a (dust-free) ring between 0.35 AU and 0.80 AU in the disk of HD 142666. The classification of AS 205 as a system of classical T Tauri stars could be confirmed using the canonical model approach, i.e., there are no hints of disk gaps in our observations.

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“…The SED that results from our best model for AS 205 N differs by about 40% from the photometric measurements of Prato et al (2003) in the NIR wavelength range (Fig. 2).…”

Section: As 205 Nmentioning

confidence: 56%

Section: As 205 Nmentioning

confidence: 99%

Multiwavelength interferometric observations and modeling of circumstellar disks

Schegerer

Ratzka

Schuller

et al. 2013

A&A

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“…It is a young (∼ 0.5 Myrs) late-type dwarf (≈K5) with mean V=12.4 mag that belongs to a hierarchical triple system. At an angular separation of 1.3 ′′ (≈180 AU at 140 pc) from AS 205A lies a very low-mass (K7/M0) spectroscopic binary (Ghez et al 1993;Prato et al 2003;Eisner et al 2005). An extensive photometric survey by Artemenko et al (2010) revealed two distinct and stable periods (P 1 =6.78 and P 2 =24.78 days) in the power spectrum of the light variations of AS 205A.…”

Section: Introductionmentioning

confidence: 99%

Evidence of a substellar companion around a very young T Tauri star

Almeida

Gameiro

Петров

et al. 2017

A&A

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We present results from a Near Infrared multi-epoch spectroscopic campaign to detect a young low-mass companion to a T Tauri star. AS 205A is a late-type dwarf (≈K5) of ∼ 1 M⊙ that belongs to a triple system. Independent photometric surveys discovered that AS 205A has two distinct periods (P 1 =6.78 and P 2 =24.78 days) detected in the light curve that persist over several years. Period P 1 seems to be linked to the axial-rotation of the star and is caused by the presence of cool surface spots. Period P 2 is correlated with the modulation in AS 205A brightness (V) and red color (V-R), consistent with a gravitating object within the accretion disk.We here derive precise Near Infrared radial velocities to investigate the origin of period P 2 which is predicted to correspond to a cool source in a Keplerian orbit with a semi-major axis of ∼0.17 AU positioned close to the inner disk radius of 0.14 AU. The radial velocity variations of AS 205A were found to have a period of P ≈ 24.84 days and a semi-amplitude of 1.529 kms −1 . This result closely resembles the P 2 period in past photometric observations (P ≈ 24.78 days). The analysis of the cross-correlation function bisector has shown no correlation with the radial velocity modulations, strongly suggesting that the period is not controlled by stellar rotation. Additional activity indicators should however be explored in future surveys. Taking this into account we found that the presence of a substellar companion is the explanation that best fits the results. We derived an orbital solution for AS 205A and found evidence of a m 2 sini ≃19.25 M Jup object in an orbit with moderate eccentricity of e ≃ 0.34. If confirmed with future observations, preferably using a multiwavelength survey approach, this companion could provide interesting constraints on brown dwarf and planetary formation models.

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“…′′ 95-17. ′′ 0 in the star-forming regions of Taurus (distance 140 pc; Torres et al 2007, age 1-2 Myr; Kraus & Hillenbrand 2009a) and Ophiuchus (distance 140 pc; Loinard et al 2008, age 1 Myr; Allers et al 2006;Luhman & Rieke 1999;Prato et al 2003) were extracted from the literature (Kraus et al 2011;Kraus & Hillenbrand 2009b;Duchêne et al 2007;Ratzka et al 2005;Haisch et al 2004;Haisch et al 2002;White & Ghez 2001;Köhler & Leinert 1998;Reipurth & Zinnecker 1993;Leinert et al 1993) (see also Table 1 for references on each object).…”

Section: Sample and Archival Datamentioning

confidence: 99%

“…Since contamination of these sources can affect the discussion of disk frequency at the age of 1-2 Myr, we eliminated these sources from our sample. For Ophiuchus, VSSG 23 was removed from our sample due to their non-coevality (d∆ log(t) ∼ 1; Prato et al 2003). Unfortunately, sufficient data on coevality and proper motions were not available for many of the Ophiuchus sources, and these systems remain to be included in the sample as binary candidates.…”

Section: Sample and Archival Datamentioning

confidence: 99%

Study of infrared excess from circumstellar disks in binaries with Spitzer/IRAC

Itoh

Fukagawa

Shibai

et al. 2015

Publications of the Astronomical Society of Japan

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The presence of excess emission at 3.6-8.0 µm was investigated in a sample of 27 binary systems located in two nearby star-forming regions, Taurus and Ophiuchus, by using Spitzer/Infrared Array Camera (IRAC) archival data. Angular (Projected) separations for the binaries are greater than 2 ′′ (∼280 AU), which allowed us to perform spatially resolved photometry of individual primary and secondary sources. The measured occurrence of infrared excess suggests that binarity plays a role in the evolution of circumstellar disks, even at such wide binary separations. Most of the binaries have excess emission from both the circumprimary and circumsecondary disks, or show photospheric levels for both components at all four wavelengths of IRAC. On the other hand, four systems (17 +11 −8 %, designated by "mixed" systems) exhibit excess emission from a single binary component. This ratio is significantly smaller than that predicted by the random pairing of single stars, suggesting that circumprimary and circumsecondary disks are synchronously dispersed. In addition, the excess frequencies (EFs) of primary and secondary sources with a projected distance of a p ≃ 280-450 AU are 100 +0 −17 % and 91 +8 −18 %, respectively, and significantly higher than that of single stars (70 ± 5%). We made a simple model describing the EF distribution as a function of the disk outer radius, R out . Comparisons with observations using the Kolmogorov-Smirnov test show that the observational data are consistent with the model when the EF ≃ 1 region is found at R out ∼ 30-100 AU. This disk radius is smaller than that typically estimated for single stars. The high EF of circumstellar disks with these radii may indicate a prolonged lifetime of dust in binary systems possibly because smaller disks counteract mass loss by photoevaporation.

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Astrophysics of Young Star Binaries

Cited by 142 publications

References 75 publications

Multiwavelength interferometric observations and modeling of circumstellar disks

Multiwavelength interferometric observations and modeling of circumstellar disks

Evidence of a substellar companion around a very young T Tauri star

Study of infrared excess from circumstellar disks in binaries with Spitzer/IRAC

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