The Herbig Ae Star HD 163296 in X‐Rays

Swartz, Douglas A.; Drake, J. J.; Elsner, Ronald F.; Ghosh, K. K.; Grady, C. A.; Wassell, E. J.; Woodgate, B. E.; Kimble, Randy A.

doi:10.1086/429984

Cited by 64 publications

(81 citation statements)

References 48 publications

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“…11 we plot log L X over the age for our sample stars. It is impossible to exclude categorically that there are further, as yet unknown, companion stars responsible for the X-ray Berghoefer et al (1996), g Swartz et al (2005), h Grady et al (2007), i Robrade, priv. comm.…”

Section: X-ray Emissionmentioning

confidence: 99%

Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars and stars with debris disks

Hubrig

Stelzer

Schöller

et al. 2009

A&A

149

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Context. Recently, evidence for the presence of weak magnetic fields in Herbig Ae/Be stars has been found in several studies. Aims. We seek to expand the sample of intermediate-mass pre-main sequence stars with circular polarization data to measure their magnetic fields, and to determine whether magnetic field properties in these stars are correlated with mass-accretion rate, disk inclination, companions, silicates, PAHs, or show a correlation with age and X-ray emission as expected for the decay of a remnant dynamo. Methods. Spectropolarimetric observations of 21 Herbig Ae/Be stars and six debris disk stars have been obtained at the European Southern Observatory with FORS 1 mounted on the 8 m Kueyen telescope of the VLT. With the GRISM 600B in the wavelength range 3250-6215 Å we were able to cover all hydrogen Balmer lines from Hβ to the Balmer jump. In all observations a slit width of 0. 4 was used to obtain a spectral resolving power of R ≈ 2000. Results. Among the 21 Herbig Ae/Be stars studied, new detections of a magnetic field were achieved in six stars. For three Herbig Ae/Be stars, we confirm previous magnetic field detections. The largest longitudinal magnetic field, B z = −454 ± 42 G, was detected in the Herbig Ae/Be star HD 101412 using hydrogen lines. No field detection at a significance level of 3σ was achieved in stars with debris disks. Our study does not indicate any correlation of the strength of the longitudinal magnetic field with disk orientation, disk geometry, or the presence of a companion. We also do not see any simple dependence on the mass-accretion rate. However, it is likely that the range of observed field values qualitatively supports the expectations from magnetospheric accretion models giving support for dipole-like field geometries. Both the magnetic field strength and the X-ray emission show hints of a decline with age in the range of ∼2-14 Myr probed by our sample, supporting a dynamo mechanism that decays with age. However, our study of rotation does not show any obvious trend of the strength of the longitudinal magnetic field with rotation period. Furthermore, the stars seem to obey the universal power-law relation between magnetic flux and X-ray luminosity established for the Sun and main-sequence active dwarf stars.

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Section: X-ray Emissionmentioning

confidence: 99%

Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars and stars with debris disks

Hubrig

Stelzer

Schöller

et al. 2009

A&A

149

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“…One of the knots (A) has also been associated with X-ray emission (Swartz et al 2005). The high-velocity gas in the jet has radial velocities of 200−300 km s −1 .…”

Section: Introductionmentioning

confidence: 99%

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Ellerbroek

Podio

Dougados

et al. 2014

A&A

131

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Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) spectra of the jet from the Herbig Ae star HD 163296, obtained with VLT/X-shooter. We determine the physical conditions in the knots and also their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ∼16 yr. The velocity dispersion versus jet velocity and the energy input are comparable between both lobes. However, the mass-loss rate, velocity, and shock conditions are asymmetric. We findṀ jet /Ṁ acc ∼ 0.01−0.1, which is consistent with magneto-centrifugal jet launching models. No evidence of any dust is found in the high-velocity jet, suggesting a launch region within the sublimation radius (<0.5 au). The jet inclination measured from proper motions and radial velocities confirms that it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the central source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are very likely caused by dust lifted high above the disk plane, and this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane.

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“…This star is one of the best candidates with which to perform a high angular and spectral study of the accretion-ejection region: HD 163296 is located at just ∼119 pc (van Leeuwen 2007), it is among the few Herbig Ae stars driving a well collimated bipolar jet (HH409; see e.g. Wassell et al 2006), and it is very likely a single star (Swartz et al 2005;Montesinos et al 2009). The main HD 163296 stellar parameters are listed in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Probing the accretion-ejection connection with VLTI/AMBER

López

Тамбовцева

Schertl

et al. 2015

A&A

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Context. Accretion and ejection are tightly connected and represent the fundamental mechanisms regulating star formation. However, the exact physical processes involved are not yet fully understood. Aims. We present high angular and spectral resolution observations of the Brγ emitting region in the Herbig Ae star HD 163296 (MWC 275) in order to probe the origin of this line and constrain the physical processes taking place at sub-AU scales in the circumstellar region. Methods. By means of VLTI-AMBER observations at high spectral resolution (R ∼ 12 000), we studied interferometric visibilities, wavelength-differential phases, and closure phases across the Brγ line of HD 163296. To constrain the physical origin of the Brγ line in Herbig Ae stars, all the interferometric observables were compared with the predictions of a line radiative transfer disc wind model. Results. The measured visibilities clearly increase within the Brγ line, indicating that the Brγ emitting region is more compact than the continuum. By fitting a geometric Gaussian model to the continuum-corrected Brγ visibilities, we derived a compact radius of the Brγ emitting region of ∼0.07 ± 0.02 AU (Gaussian half width at half maximum; or a ring-fit radius of ∼0.08 ± 0.02 AU). To interpret the observations, we developed a magneto-centrifugally driven disc wind model. Our best disc wind model is able to reproduce, within the errors, all the interferometric observables and it predicts a launching region with an outer radius of ∼0.04 AU. However, the intensity distribution of the entire disc wind emitting region extends up to ∼0.16 AU. Conclusions. Our observations, along with a detailed modelling of the Brγ emitting region, suggest that most of the Brγ emission in HD 163296 originates from a disc wind with a launching region that is over five times more compact than previous estimates of the continuum dust rim radius.

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The Herbig Ae Star HD 163296 in X‐Rays

Cited by 64 publications

References 48 publications

Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars and stars with debris disks

Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars and stars with debris disks

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Probing the accretion-ejection connection with VLTI/AMBER

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