Infrared Interferometric Observations of Young Stellar Objects

Akeson, Rachel; Ciardi, David R.; Belle, Gerald van; Creech‐Eakman, M. J.; Lada, Elizabeth A.

doi:10.1086/317111

Cited by 59 publications

(76 citation statements)

References 16 publications

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“…Although we find some qualitative agreement, we are forced to conclude that our images are inconsistent with classical accretion disk models. This reinforces findings from recently reported high-resolution observations of the Herbig objects with the Infrared Optical Telescope Array (IOTA) [23,24] and the Palomar Testbed Interferometer [25]. Although most of the visibility data fitted with standard viscously-heated accretion disks (T ∝ R −3 4 ), an unlikely set of extreme inclination angles was required [24]).…”

supporting

confidence: 87%

A dusty torus around the luminous young star LkHα101

Tuthill

Monnier

Danchi

2001

Nature

117

107

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A star forms when a cloud of dust and gas collapses. It is generally believed that this collapse first produces a flattened rotating disk [1,2], through which matter is fed onto the embryonic star at the center of the disk. When the temperature and density at the center of the star pass a critical threshold, thermonuclear fusion begins. The remaining disk, which can still contain up to ∼0.3 times the mass of the star [3,4,5], is then sculpted and eventually dissipated by the radiation and wind from the newborn star. Unfortunately this picture of the structure and evolution of the disk remains speculative because of the lack of morphological data of sufficient resolution and uncertainties regarding the underlying physical processes. Here we present resolved images of a young star, LkHα 101 in which the structure of the inner accretion disk is resolved. We find that the disk is almost face-on, with a central gap (or cavity) and a hot inner edge. The cavity is bigger than previous theoretical predictions[6], and we infer that the position of the inner edge is probably determined by sublimation of dust grains by direct stellar radiation, rather than by disk reprocessing or the viscous heating processes as usually assumed [7].The Herbig Ae/Be stars, thought to be pre-main-sequence stars of intermediate mass, have generated considerable recent controversy over their circumstellar structure. Accretion-disk models were found to fit the spectral energy distribution (SED) provided that an optically thin hole or cavity was allowed around the central star [6,8]. This model drew almost immediate criticism over missing accretion luminosity [9] and problems with forbidden emission line profiles not matching expectations [10]. Further confusion arose from the finding that the SED could be fitted by spherically-symmetric circumstellar shells [11,12] or composite shell-disk models [13].LkHα 101 is amongst the brightest young stellar objects in the near-infrared, despite its location behind considerable line-of-sight obscuration (recent estimates of visible extinction A v range from 9.4[14] to 18.5 [15]). Interferometric observations with the Keck I telescope capable of imaging structure on scales of tens of milli-arcseconds [16] have enabled us to observe the circumstellar environment of LkHα 101 in the near-infrared at an unprecedented level of detail.

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supporting

confidence: 87%

A dusty torus around the luminous young star LkHα101

Tuthill

Monnier

Danchi

2001

Nature

117

107

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“…Supporting evidence for the flared disk model is accumulating from observations in the near-IR. Near-IR interferometry has resolved emission around Herbig stars of much larger radial extent than expected from the flat disk models (Millan-Gabet, Schloerb, & Traub 2001;Akeson et al 2000Akeson et al , 2002Tuthill, Monnier, & Danchi 2001). These observations could be explained by either a variation on the flared disk model (Natta et al 2001) or by a thin circumstellar shell (Millan-Gabet et al 2001).…”

Section: No 4 2002mentioning

confidence: 98%

“…Optical spectra show radial velocity variations that may be due to a close companion (Vieira & Cunha 1994;Corporon & Lagrange 1999), and near-IR imaging and interferometry have suggested a more distant companion (Akeson et al 2000;Corporon 1998). Near-IR spectroscopy has shown strong emission from polycyclic aromatic hydrocarbon (PAH) grains extending 12 00 (Brooke et al 1993;Jourdain de Muizon, d'Hendecourt, & Geballe 1990).…”

Section: Hd 259431mentioning

confidence: 99%

The Dusty Circumstellar Environments of A[CLC]e[/CLC]/B[CLC]e[/CLC] Protoplanetary Disk Candidates

Polomski

Telesco

Piña

et al. 2002

The Astronomical Journal

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We have obtained high spatial resolution mid-IR observations of four intermediate-mass pre-mainsequence stars: HD 259431, AS 310, LkH 234, and MWC 1080. Our observations reveal the morphology of the circumstellar (500-10,000 AU) environments of these young stars. We resolve companion stars and complex diffuse emission from dust that can account for on average 50% of the IR emission detected in previous low-resolution observations. We calculate new spectral indices for these objects and show that they differ from those expected from simple geometrically flat disk models. We also show mid-IR spectral energy distributions that reveal the presence of silicate emission and absorption features for several objects. Finally, temperature maps constructed from our observations suggest the presence of transiently heated grains, and optical depth maps point to the locations of the most embedded objects.

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“…(right panel) The first classical T Tauri stars were observed by the PTI interferometer and also showed larger than expected infrared sizes. Here is the original data for T Tau itself, an important source but whose analysis is complicated by uncertain calibration due to the presence of a nearby companion in the interferometer field-of-view (see Figure 1a by Akeson et al, 2000a). Both figures are reproduced with permission of the AAS.…”

Section: Accretion Disks and Young Stellar Objectsmentioning

confidence: 99%

Optical interferometry in astronomy

2003

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Abstract. Here I review the current state of the field of optical stellar interferometry, concentrating on ground-based work although a brief report of space interferometry missions is included. We pause both to reflect on decades of immense progress in the field as well as to prepare for a new generation of large interferometers just now being commissioned (most notably, the CHARA, Keck and VLT Interferometers). First, this review summarizes the basic principles behind stellar interferometry needed by the lay-physicist and general astronomer to understand the scientific potential as well as technical challenges of interferometry. Next, the basic design principles of practical interferometers are discussed, using the experience of past and existing facilities to illustrate important points. Here there is significant discussion of current trends in the field, including the new facilities under construction and advanced technologies being debuted. This decade has seen the influence of stellar interferometry extend beyond classical regimes of stellar diameters and binary orbits to new areas such as mapping the accretion disks around young stars, novel calibration of the Cepheid Period-Luminosity relation, and imaging of stellar surfaces. The third section is devoted to the major scientific results from interferometry, grouped into natural categories reflecting these current developments. Lastly, I consider the future of interferometry, highlighting the kinds of new science promised by the interferometers coming on-line in the next few years. I also discuss the longer-term future of optical interferometry, including the prospects for space interferometry and the possibilities of large-scale ground-based projects. Critical technological developments are still needed to make these projects attractive and affordable. †

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Infrared Interferometric Observations of Young Stellar Objects

Cited by 59 publications

References 16 publications

A dusty torus around the luminous young star LkHα101

A dusty torus around the luminous young star LkHα101

The Dusty Circumstellar Environments of A[CLC]e[/CLC]/B[CLC]e[/CLC] Protoplanetary Disk Candidates

Optical interferometry in astronomy

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