Spiral Structure in the Circumstellar Disk around AB Aurigae

Fukagawa, Misato; Hayashi, Masahiko; Tamura, Motohide; Itoh, Yoichi; Hayashi, Saeko S.; Oasa, Yumiko; Takeuchi, Taku; Morino, Jun-Ichi; Murakawa, K.; Oya, Shin; Yamashita, Takuya; Shimada, Hiroshi; Mayama, Satoshi; Naoi, Takahiro; Ishii, Miki; Pyo, Tae‐Soo; Nishikawa, Takayuki; Takato, Naruhisa; Usuda, Tomonori; Ando, Hiroyasu; Iye, Masanori; Miyama, Shoken M.; Kaifu, Norio

doi:10.1086/420699

Cited by 205 publications

(234 citation statements)

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“…Nearinfrared scattered-light imaging observations probe the spatial distribution of small grains, approximately micron-sized or smaller, that are well coupled to the gas (Pinilla et al 2012;Zhu et al 2012). These studies have revealed spiral arms in a growing number of disks (Figure 1), both prominent near-symmetric twoarm spirals (e.g., Grady et al 2013;Benisty et al 2015) and more flocculent multiarm spirals on smaller scales and at lower contrast (e.g., Fukagawa et al 2004;Hashimoto et al 2011). Spiral arms can be produced by either gravitational instability (e.g., Rice et al 2003;Lodato & Rice 2004;Stamatellos & Whitworth 2008;Kratter et al 2010;Kratter & Lodato 2016) or the presence of massive companions (gas giant to stellar masses; e.g., Kley & Nelson 2012;Zhu et al 2015;Muñoz & Lai 2016).…”

Section: Introductionmentioning

confidence: 99%

Spiral Arms in Disks: Planets or Gravitational Instability?

Dong

Najita

Brittain

2018

ApJ

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Spiral arm structures seen in scattered-light observations of protoplanetary disks can potentially serve as signposts of planetary companions. They can also lend unique insights into disk masses, which are critical in setting the mass budget for planet formation but are difficult to determine directly. A surprisingly high fraction of disks that have been well studied in scattered light have spiral arms of some kind (8/29), as do a high fraction (6/11) of wellstudied Herbig intermediate-mass stars (i.e., Herbig stars >1.5 M e ). Here we explore the origin of spiral arms in Herbig systems by studying their occurrence rates, disk properties, and stellar accretion rates. We find that two-arm spirals are more common in disks surrounding Herbig intermediate-mass stars than are directly imaged giant planet companions to mature A and B stars. If two-arm spirals are produced by such giant planets, this discrepancy suggests that giant planets are much fainter than predicted by hot-start models. In addition, the high stellar accretion rates of Herbig stars, if sustained over a reasonable fraction of their lifetimes, suggest that disk masses are much larger than inferred from their submillimeter continuum emission. As a result, gravitational instability is a possible explanation for multiarm spirals. Future observations can lend insights into the issues raised here.

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Section: Introductionmentioning

confidence: 99%

Spiral Arms in Disks: Planets or Gravitational Instability?

Dong

Najita

Brittain

2018

ApJ

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“…More recently, spatially resolved dust and molecular line observations in the millimeter and sub-millimeter domain (e.g., Mannings & Sargent 1997;Semenov et al 2005), together with scattered light coronographic imaging (e.g., Fukagawa et al 2004, Grady et al 2005 provided direct evidence that Herbig Ae/Be stars are effectively surrounded by a disk (for a detailed review about Herbig Ae/Be stars see Waters & Waelkens 1998). 1 The origin of the H i emission lines in Herbig Ae/Be stars is in fact controversial.…”

Section: Introductionmentioning

confidence: 99%

New Herbig Ae/Be stars confirmed via high-resolution optical spectroscopy

Ancker

Audard²,

Henning

et al. 2010

A&A

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We present FEROS high-resolution (R ∼ 45 000) optical spectroscopy of 34 Herbig Ae/Be star candidates with previously unknown or poorly constrained spectral types. Within the sample, 16 sources are positionally coincident with nearby (d < 250 pc) star-forming regions (SFRs). All the candidates have reported infrared excess. We determine the spectral type and luminosity class of the sources, derive their radial and projected rotational velocities, and constrain their distances employing spectroscopic parallaxes and photometry from the literature. We confirm 13 sources as Herbig Ae/Be stars and find one classical T Tauri star. Three sources are emission line early-type giants (B, A, and F stars with luminosity class III) and may be Herbig Ae/Be stars. One source is a main-sequence Atype star. Fourteen sources are post-main-sequence giant and supergiant stars (7 with Hα emission and 7 without). Two sources are extreme emission-line stars and no accurate spectral classification was possible because of strong veiling. Most of the sources appear to be background stars at distances over 700 pc. We show that high-resolution optical spectroscopy is a crucial tool for distinguishing young stars (in particular Herbig Be stars) from post-main sequence stars in samples taken from emission-line star catalogs based on low-resolution spectroscopy. Within the sample, three young stars (CD-38 4380, Hen 3-1145, and HD 145718) and one early-type luminosity class III giant with emission lines (Hen 3-416) are at distances closer than 300 pc and are positionally coincident with a nearby SFR. These 4 sources are likely to be nearby young stars and are interesting for follow-up observations at high-angular resolution. Furthermore, seven confirmed Herbig Ae/Be stars at d > 700 pc (Hen 2-80, Hen 3-1121 N&S, HD 313571, MWC 953, WRAY 15-1435, and Th 17-35) are inside or close (<5 ) to regions with extended 8 μm continuum emission and in their 20 vicinity have astronomical sources characteristic of SFRs (e.g., HII regions, molecular clouds, dark nebulae, masers, young stellar-objects). These 7 sources are likely to be members of SFRs.

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“…In both cases, however, the observed visibility variation could not be modeled with the wind alone so we considered an additional component producing an extended continuum emission. This component could come from the extended reflection nebulosity around the system, already reported by several authors (Grady et al 1999b;Fukagawa et al 2004;Millan-Gabet et al 2006). In practice, we used this secondary source to reproduce the modulation of the visibility in the continuum.…”

Section: Modeling and Discussionmentioning

confidence: 99%

“…AB Aur is surrounded by a complex combination of gasrich and dust-dominated structures probed on large scales by imaging. Using the HST, Grady et al (1999b) detected extended nebulosity and circumstellar material at all position angles out to 1320 AU in the R-band, whereas Fukagawa et al (2004) detected a double spiral structure at 200−450 AU in the Hband. Spatially resolved observations at high angular resolution at near-infrared, thermal infrared, and millimetric wavelengths have shown the presence of a circumstellar disk (Millan-Gabet et al 2001;Eisner et al 2004), rotating at non-Keplerian velocities (Piétu et al 2005).…”

Section: The Target: Ab Aurigaementioning

confidence: 99%

The Hαline forming region of AB Aurigae spatially resolved at sub-AU with the VEGA/CHARA spectro-interferometer

Rousselet-Perraut¹,

Benisty

Mourard³

et al. 2010

A&A

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Context. A crucial issue in star formation is to understand the physical mechanism by which mass is accreted onto and ejected by a young star. To derive key constraints on the launching point of the jets and on the geometry of the winds, the visible spectropolarimeter VEGA installed on the CHARA optical array can be an efficient means of probing the structure and the kinematics of the hot circumstellar gas at sub-AU. Aims. For the first time, we observed the Herbig Ae star AB Aur in the Hα emission line, using the VEGA low spectral resolution (R = 1700) on two baselines of the array. Methods. We computed and calibrated the spectral visibilities of AB Aur between 610 nm and 700 nm in spectral bands of 20.4 nm. To simultaneously reproduce the line profile and the inferred visibility around Hα, we used a 1D radiative transfer code (RAMIDUS/PROFILER) that calculates level populations for hydrogen atoms in a spherical geometry and that produces synthetic spectro-interferometric observables. Results. We clearly resolved AB Aur in the Hα line and in a part of the continuum, even at the smallest baseline of 34 m. The small P-Cygni absorption feature is indicative of an outflow but could not be explained by a spherical stellar wind model. Instead, it favors a magneto-centrifugal X-disk or disk-wind geometry. The fit of the spectral visibilities from 610 to 700 nm could not be accounted for by a wind alone, so another component inducing a visibility modulation around Hα needed to be considered. We thus considered a brightness asymmetry possibly caused by large-scale nebulosity or by the known spiral structures. Conclusions. Thanks to the unique capabilities of VEGA, we managed to simultaneously record for the first time a spectrum at a resolution of 1700 and spectral visibilities in the visible range on a target as faint as m V = 7.1. It was possible to rule out a spherical geometry for the wind of AB Aur and provide realistic solutions to account for the Hα emission compatible with magneto-centrifugal acceleration. It was difficult, however, to determine the exact morphology of the wind because of the surrounding asymmetric nebulosity. The study illustrates the advantages of optical interferometry and motivates observations of other bright young stars in the same way to shed light on the accretion/ejection processes.

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Spiral Structure in the Circumstellar Disk around AB Aurigae

Cited by 205 publications

References 28 publications

Spiral Arms in Disks: Planets or Gravitational Instability?

Spiral Arms in Disks: Planets or Gravitational Instability?

New Herbig Ae/Be stars confirmed via high-resolution optical spectroscopy

The Hαline forming region of AB Aurigae spatially resolved at sub-AU with the VEGA/CHARA spectro-interferometer

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