The absorption and emission spectrum of the magnetic Herbig Ae star HD 190073

Cowley, C. R.; Hubrig, S.

doi:10.1002/asna.201111589

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…This may represent the development of chemical peculiarities over time during the pre-main sequence, however a larger sample size is needed to draw firm conclusions. These results agree well with the work of Cowley et al (2010) who independently found λ Boo peculiarities in HD 101412, and Cowley & Hubrig (2012) who found solar abundances in HD 190073. Cowley et al (2013) and Cowley et al (in press) report an additional chemically normal HAeBe star and a λ Boo HAeBe star, further supporting the very high incidence of λ Boo peculiarities among HAeBe stars.…”

Section: Discussionsupporting

confidence: 92%

Chemical peculiarities in magnetic and non-magnetic pre-main sequence A and B stars

Folsom¹,

Bagnulo²,

Wade³

et al. 2013

Proc. IAU

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Abstract. In A-and late B-type stars, strong magnetic fields are always associated with Ap and Bp chemical peculiarities. However, it is not clear at what point in a star's evolution those peculiarities develop. Strong magnetic fields have been observed in pre-main sequence A and B stars (Herbig Ae and Be stars), and these objects have been proposed to be the progenitors of Ap and Bp stars. However, the photospheric chemical abundances of these magnetic Herbig stars have not been studied carefully, and furthermore the chemical abundances of 'normal' non-magnetic Herbig stars remain poorly characterized. To investigate this issue, we have studied the photospheric compositions of 23 Herbig stars, four of which have confirmed magnetic fields. Surprisingly, we found that half the non-magnetic stars in our sample show λ Bootis chemical peculiarities to varying degrees. For the stars with detected magnetic fields, we find one chemically normal star, one star with λ Boo peculiarities, one star displaying weak Ap/Bp peculiarities, and one somewhat more evolved star with somewhat stronger Ap/Bp peculiarities. These results suggests that Ap/Bp peculiarities are preceded by magnetic fields, and that these peculiarities develop over the pre-main sequence lives of A and B stars. The incidence of λ Boo stars we find is much higher than that seen on the main sequence. We argue that a selective accretion model for the formation of λ Boo peculiarities is a natural explanation for this remarkably large incidence.

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Section: Discussionsupporting

confidence: 92%

Chemical peculiarities in magnetic and non-magnetic pre-main sequence A and B stars

Folsom¹,

Bagnulo²,

Wade³

et al. 2013

Proc. IAU

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“…The absorption and emission spectrum of the Herbig Ae star HD 190073 was studied in detail by Catala et al (2007) and more recently by Cowley & Hubrig (2012). The low projected rotational velocity (v sin i ≤ 9 km s −1 ) may indicate either a very slow rotation, or a very small inclination of the rotation axis with respect to the line of sight.…”

Section: Hd 190073mentioning

confidence: 99%

HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights

Järvinen

Carroll

Hubrig

et al. 2015

A&A

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Aims. Recently, several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be a promising approach for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundances, and allow us to identify a proper sample of spectral lines appropriate for magnetic field determination. Methods. High-resolution spectropolarimetric observations of the three sharp-lined (v sin i < 15 km s −1 ) Herbig Ae stars HD 101412, HD 104237, and HD 190073 have been obtained in recent years with the HARPS spectrograph in polarimetric mode. We used these archival observations to investigate the behaviour of their longitudinal magnetic fields. To carry out the magnetic field measurements, we used the multi-line singular value decomposition (SVD) method for Stokes profile reconstruction. Results. We carried out a high-resolution spectropolarimetric analysis of the Herbig Ae star HD 101412 for the first time. We discovered that different line lists yield differences in both the shape of the Stokes V signatures and their field strengths. They could be interpreted in the context of the impact of the circumstellar matter and elemental abundance inhomogeneities on the measurements of the magnetic field. On the other hand, due to the small size of the Zeeman features on the first three epochs and the lack of near-IR observations, circumstellar and photospheric contributions cannot be estimated unambiguously. In the SVD Stokes V spectrum of the SB2 system HD 104237, we detect that the secondary component, which is a T Tauri star, possesses a rather strong magnetic field B z = 129 ± 12 G, while no significant field is present in the primary component. Our measurements of HD 190073 confirm the presence of a variable magnetic field and indicate that the circumstellar environment may have a significant impact on the observed polarization features.

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“…The absorption and emission spectrum of the Herbig Ae/Be star HD 190073 was studied in detail by Catala et al (2007) and more recently by Cowley & Hubrig (2012). The low projected rotational velocity (v sin i ≤ 9 km s −1 ) may indicate either a very slow rotation, or a very small inclination of the rotation axis with respect to the line of sight.…”

Section: Reduction Of Harps Spectra and Notes On The Samplementioning

confidence: 99%

HARPS spectropolarimetry of Herbig Ae/Be stars

et al. 2013

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Our knowledge of the presence and the strength of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present new magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in spectropolarimetric mode. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS spectra for six Herbig Ae/Be stars. Wavelength shifts between right-and left-hand side circularly polarised spectra were interpreted in terms of a longitudinal magnetic field Bz , using the moment technique introduced by Mathys. The application of the moment technique to the HARPS spectra allowed us in addition to study the presence of the crossover effect and quadratic magnetic fields. Our search for longitudinal magnetic fields resulted in first detections of weak magnetic fields in the Herbig Ae/Be stars HD 58647 and HD 98922. Further, we confirm the previous tentative detection of a weak magnetic field in HD 104237 by Donati et al. and confirm the previous detection of a magnetic field in the Herbig Ae star HD 190073. Surprisingly, the measured longitudinal magnetic field of HD 190073, Bz = 91 ± 18 G at a significance level of 5σ is not in agreement with the measurement results of Alecian et al. (2013), Bz = −10 ± 20 G, who applied the LSD method to exactly the same data. No crossover effect was detected for any star in the sample. Only for HD 98922 the crossover effect was found to be close to 3σ with a measured value of −4228±1443 km s −1 G. A quadratic magnetic field of the order of 10 kG was detected in HD 98922, and of ∼3.5 kG in HD 104237.

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The absorption and emission spectrum of the magnetic Herbig Ae star HD 190073

Cited by 7 publications

References 25 publications

Chemical peculiarities in magnetic and non-magnetic pre-main sequence A and B stars

Chemical peculiarities in magnetic and non-magnetic pre-main sequence A and B stars

HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights

HARPS spectropolarimetry of Herbig Ae/Be stars

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