Sicyon

Clark, William George

doi:10.1017/cbo9781139161794.025

Cited by 3 publications

(4 citation statements)

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“…They achieved contrast limits of 4.0 mag, so a fainter (i.e., lower mass or more deeply embedded) object would have been missed in their observations. Furthermore, they measured the inclination of the disk surrounding R CrA to be ∼35 • , (confirming previous results from, e.g., Clark et al 2000) and its PA to be ∼180 • −190 • . In this paper, we present the results of new high-contrast imaging L -band observations of R CrA that find direct evidence for a stellar companion.…”

Section: Introductionsupporting

confidence: 84%

ISPY – NaCo Imaging Survey for Planets around Young stars

Cugno

Quanz

Launhardt

et al. 2019

A&A

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Context. Within the NaCo-ISPY exoplanet imaging program, we aim at detecting and characterizing the population of low-mass companions at wide separations ( 10 AU), focusing in particular on young stars either hosting a known protoplanetary disk or a debris disk. Aims. R CrA is one of the youngest (1-3 Myr) and most promising objects in our sample because of two previous studies that suggested the presence of a close companion. Our aim is to directly image and characterize the companion for the first time. Methods. We observed R CrA twice with the NaCo instrument at the Very Large Telescope (VLT) in the L filter with a one year time baseline in between. The high-contrast imaging data were reduced and analyzed and the companion candidate was detected in both datasets. We used artificial negative signals to determine the position and brightness of the companion and the related uncertainties.Results. The companion is detected at a separation of 196.8 ± 4.5/196.6 ± 5.9 mas (18.7 ± 1.3/18.7 ± 1.4 AU) and position angle of 134.7 ± 0.5 • /133.7 ± 0.7 • in the first/second epoch observation. We measure a contrast of 7.29 ± 0.18/6.70 ± 0.15 mag with respect to the primary. A study of the stellar proper motion rejects the hypothesis that the signal is a background object. The companion candidate orbits in the clockwise direction and, if on a face-on circular orbit, its period is ∼43−47 yr. This value disagrees with the estimated orbital motion and therefore a face-on circular orbit may be excluded. Depending on the assumed age, extinction, and brightness of the primary, the stellar companion has a mass between 0.10 ± 0.02 M and 1.03 +0.20 −0.18 M range, if no contribution from circumsecondary material is taken into account. Conclusions. As already hypothesized by previous studies, we directly detected a low-mass stellar companion orbiting the young Herbig Ae/Be star R CrA. Depending on the age assumptions, the companion is among the youngest forming companions imaged to date, and its presence needs to be taken into account when analyzing the complex circumstellar environment of R CrA.

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Section: Introductionsupporting

confidence: 84%

ISPY – NaCo Imaging Survey for Planets around Young stars

Cugno

Quanz

Launhardt

et al. 2019

A&A

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“…There are three likely mechanisms for CP in star forming regions: multiple scattering in an optically thick region of dust grains, dichroic scattering by (partially) aligned non-spherical dust grains, and dichroic extinction of linearly polarized radiation in (partially) aligned non-spherical dust grains (Ménard et al 1988;Chrysostomou et al 2000;Gledhill & McCall 2000;Buschermöhle et al 2005). Although the effective mechanism of CP may depend on the environment, previous studies show that higher mass young stellar objects have larger CP (Gledhill et al 1996;Bailey et al 1998;Clark et al 2000;Ménard et al 2000;Clayton et al 2005;Chrysostomou et al 2007). Further studies of star-forming regions by near-infrared imaging circular polarimetry are necessary to assess the generation mechanism for CP.…”

Section: Introductionmentioning

confidence: 97%

Near-Infrared Circular Polarimetry and Correlation Diagrams in the Orion Becklin-Neugebauer/Kleinman-Low Region: Contribution of Dichroic Extinction

Fukue

Tamura

Kandori

et al. 2009

ApJ

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We present a deep circular polarization image of the Orion BN/KL nebula in the K s band and correlations of circular polarization, linear polarization, and H-K s color representing extinction. The image of circular polarization clearly reveals the quadrupolar structure around the massive star IRc2, rather than BN. H-K s color is well correlated with circular polarization. A simple relation between dichroic extinction, color excess, circular and linear polarization is derived. The observed correlation between the Stokes parameters and the color excess agrees with the derived relation, and suggests a major contribution of dichroic extinction to the production of circular polarization in this region, indicating the wide existence of aligned grains.

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“…The inclination of the ring with respect to the plane of the sky is 44 • +8 −17 . This is fully consistent with the inclination of the plane (40 • ) perpendicular to the symmetry axis of the bipolar reflection nebula as suggested from NIR imaging polarimetry [20]. However, the derived position angle of the disk symmetry axis (62 • +14 −7 ) is only marginally consistent with R CrA as the driving source for the extended NE-SW molecular outflow at PA∼ 30 • [15], [16].…”

Section: Disk Structure and Orientationsupporting

confidence: 83%

“…R CrA is a bright (100 L ⊙ ) young Herbig A5e star, located at the center of a small cluster (The Coronet [8] [9]) at 130 pc [10]. Several characteristics indicate the presence of a circumstellar disk around R CrA : a flat mid-IR to far-IR/mm SED 3 ([2]), a broad silicate emission feature [12], a UX Ori Type [13], a high degree (8%) of optical linear polarisation [14] , the possible association with a extended molecular outflow [15], [16] as well as with several Herbig-Haro systems [17], and a near-infrared reflection nebulosity whose resolved spatial polarization is consistent with a bipolar outflow being truncated by an evacuated spherical cavity [20]. [18].…”

Section: Introductionmentioning

confidence: 99%

First Evidence for a Spatially Resolved Disk Structure around the Herbig Ae Star R CrA

Correia

Köhler

Meeus

et al.

The Power of Optical/Ir Interferometry: Recent Scientific Results and 2nd Generation Instrumentation

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We present mid-infrared interferometric observations of the Herbig Ae star R CrA obtained with MIDI at the VLTI using several projected baselines in the UT2-UT3 configuration. The observations show resolved circumstellar emission in the wavelength range 8-13 µm on a ∼ 6 AU scale with a non-symmetric intensity distribution, providing support for an inclined disk geometry. Visibilities are best fitted using a uniform ring model with outer radius in the range 6-10 AU, in the wavelength range 8-13 micron. The inclination of the ring with respect to the plane of the sky is found to be ∼ 45 • , consistent with the 40 • suggested from near-infrared imaging polarimetry (Clark et al. 2000, MNRAS, 319, 337).

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Sicyon

Cited by 3 publications

References 0 publications

ISPY – NaCo Imaging Survey for Planets around Young stars

ISPY – NaCo Imaging Survey for Planets around Young stars

Near-Infrared Circular Polarimetry and Correlation Diagrams in the Orion Becklin-Neugebauer/Kleinman-Low Region: Contribution of Dichroic Extinction

First Evidence for a Spatially Resolved Disk Structure around the Herbig Ae Star R CrA

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