The Evolutionary Status of UX Orionis–Type Stars

Natta, A.; Гринин, В. П.; Mannings, V.; Ungerechts, H.

doi:10.1086/305006

Cited by 103 publications

(80 citation statements)

References 28 publications

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“…According to Meeus et al (2001), HD 142666 is a group-II object whose disk is flat. The object is a photometrically variable UX Ori star (Natta et al 1997), i.e., dust clouds with a size in the range of the stellar diameter move into the line of sight of the observer from time to time. The extinction then increases and the stellar light can be reddened depending on the absorbing material.…”

Section: Appendix A: Previous Measurementsmentioning

confidence: 99%

“…Considering polarimetric measurements (Hales et al 2006) and the high variability of the flux in the NIR and visual wavelength range (ΔV = 1.2; Meeus et al 1998), the disk is assumed to be inclined. The approximate age of the object is 10 million years (Natta et al 1997). Millimeter measurements indicate this age, as well.…”

Section: Appendix A: Previous Measurementsmentioning

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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Section: Appendix A: Previous Measurementsmentioning

confidence: 99%

Section: Appendix A: Previous Measurementsmentioning

confidence: 99%

Multiwavelength interferometric observations and modeling of circumstellar disks

Schegerer

Ratzka

Schuller

et al. 2013

A&A

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“…Several different explanations for this variability have been suggested. One explanation assumes that the brightness variations are linked to obscurations of the central star by orbiting dust clouds in an almost edge-on disk (Grinin et al 1991;Natta et al 1997). Dynamical effects like gravitating bodies might also lead to regular perturbations of the density structure in the disk (see, e.g., de Wit et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Resolving the inner disk of UX Orionis

Kreplin

Madlener

Chen

et al. 2016

A&A

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Aims. The cause of the UX Ori variability in some Herbig Ae/Be stars is still a matter of debate. Detailed studies of the circumstellar environment of UX Ori objects (UXORs) are required to test the hypothesis that the observed drop in photometry might be related to obscuration events. Methods. Using near-and mid-infrared interferometric AMBER and MIDI observations, we resolved the inner circumstellar disk region around UX Ori. Results. We fitted the K-, H-, and N-band visibilities and the spectral energy distribution (SED) of UX Ori with geometric and parametric disk models. The best-fit K-band geometric model consists of an inclined ring and a halo component. We obtained a ring-fit radius of 0.45 ± 0.07 AU (at a distance of 460 pc), an inclination of 55.6 ± 2.4 • , a position angle of the system axis of 127.5 ± 24.5 • , and a flux contribution of the over-resolved halo component to the total near-infrared excess of 16.8 ± 4.1%. The best-fit N-band model consists of an elongated Gaussian with a HWHM ∼ 5 AU of the semi-major axis and an axis ration of a/b ∼ 3.4 (corresponding to an inclination of ∼72 • ). With a parametric disk model, we fitted all near-and mid-infrared visibilities and the SED simultaneously. The model disk starts at an inner radius of 0.46 ± 0.06 AU with an inner rim temperature of 1498 ± 70 K. The disk is seen under an nearly edge-on inclination of 70 ± 5 • . This supports any theories that require high-inclination angles to explain obscuration events in the line of sight to the observer, for example, in UX Ori objects where orbiting dust clouds in the disk or disk atmosphere can obscure the central star.

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“…A significant part of HAEBE stars with a spectral type later than A0 show strong photometric variability with sudden quasi-Algol drops in brightness and amplitudes up to 2. m 5 (V ) (Natta et al 1997, van den Ancker et al 1998. During the deep minimums of brightness, an increase in polarization and specific color variability are observed.…”

Section: Introductionmentioning

confidence: 99%

Optical photometry of GM Cep: evidence for UXor type of variability

Semkov

Peneva

2011

Astrophys Space Sci

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Results from optical photometric observations of the pre-main sequence star GM Cep are reported in the paper. The star is located in the field of the young open cluster Trumpler 37 -a region of active star formation. GM Cep shows a large amplitude rapid variability interpreted as a possible outburst from EXor type in previous studies. Our data from BV RI CCD photometric observations of the star are collected from June 2008 to February 2011 in Rozhen observatory (Bulgaria) and Skinakas observatory (Crete, Greece). A sequence of sixteen comparison stars in the field of GM Cep was calibrated in the BV RI bands. Our photometric data for a 2.5 years period show a high amplitude variations (∆V ∼ 2. m 3) and two deep minimums in brightness are observed. The analysis of collected multicolor photometric data shows the typical of UX Ori variables a color reversal during the minimums in brightness. On the other hand, high amplitude rapid variations in brightness typical for the Classical T Tauri stars also present on the light curve of GM Cep. Comparing our results with results published in the literature, we conclude that changes in brightness are caused by superposition of both: (1) magnetically channeled accretion from the circumstellar disk, and (2) occultation from circumstellar clouds of dust or from features of a circumstellar disk.

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The Evolutionary Status of UX Orionis–Type Stars

Cited by 103 publications

References 28 publications

Multiwavelength interferometric observations and modeling of circumstellar disks

Multiwavelength interferometric observations and modeling of circumstellar disks

Resolving the inner disk of UX Orionis

Optical photometry of GM Cep: evidence for UXor type of variability

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