Photometric variability of the Herbig Ae star HD 37806

Ruciński, S. M.; Zwintz, K.; Hareter, M.; Pojmański, G.; Kuschnig, R.; Matthews, J. M.; Guenther, D. B.; Moffat, A. F. J.; Sasselov, Dimitar; Weiß, W. W.

doi:10.1051/0004-6361/201014856

Cited by 15 publications

(12 citation statements)

References 33 publications

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“…The behaviour of MWC 480 resembles the characteristics typical of other photometrically monitored Herbig Ae/Be stars, for which light variations are likely of stochastic nature and caused by the pre-main-sequence disk accretion phenomena (e.g. Rucinski et al 2010). Using archive Hipparcos data, we have found an indication of a variability with a period of 1.6 d. However, it seems that six outliers appear during the period HJD 8674.…”

Section: Discussionsupporting

confidence: 57%

Characterising the magnetic fields of the Herbig Ae/Be stars HD 97048, HD 150193, HD 176386, and MWC 480

Hubrig

Schöller

Ilyin

et al. 2011

A&A

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Context. Our knowledge of the presence and the role of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. Aims. We present the magnetic properties of four Herbig Ae/Be stars that have not been previously studied in detail. Methods. Our results for the three Herbig Ae/Be stars HD 97048, HD 150193, and HD 176386 are based on multi-epoch lowresolution spectra obtained in spectropolarimetric mode with FORS 2 mounted on the VLT. New high-resolution polarimetric spectra were obtained for MWC 480 with the SOFIN spectrograph installed at the Nordic Optical Telescope. We discuss 41 FORS 2 lowresolution observations of the Herbig Ae/Be stars HD 97048, HD 150193, and HD 176386 and determine their rotational periods. Using stellar fundamental parameters and the longitudinal magnetic field phase curves, we place constraints on the magnetic field geometry. Three high-resolution circularly polarised SOFIN spectra obtained for MWC 480 were measured using the moment technique where wavelength shifts between right-and left-hand side circularly polarised spectra are interpreted in terms of a longitudinal magnetic field B z . Results. Our search for periodicities resulted in P = 0.693 d for HD 97048, P = 1.317 d for HD 150193, and P = 0.899 d for HD 176386. The magnetic field geometry can likely be described by a centred dipole with a polar magnetic field strength B d of several hundred Gauss. The longitudinal magnetic-field measurements of MWC 480 reveal the presence of a strong kG field, which was undetected in our previous low-resolution polarimetric observations with FORS 1. A weak magnetic field was detected in the circumstellar components of the Ca ii H&K lines and the Na i D lines, indicating a complex interaction between the stellar magnetic field and the circumstellar environment.

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Section: Discussionsupporting

confidence: 57%

Characterising the magnetic fields of the Herbig Ae/Be stars HD 97048, HD 150193, HD 176386, and MWC 480

Hubrig

Schöller

Ilyin

et al. 2011

A&A

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“…These more or less stochastic variations amount to up to several hundreds of a magnitude on timescales from several minutes to tens of years (see e.g. Ruczinski et al 2010). The light changes of HD 101412 in V and I presented in Fig.…”

Section: Appendix B: Non-periodic Variationsmentioning

confidence: 95%

Rotationally modulated variations and the mean longitudinal magnetic field of the Herbig Ae star HD 101412

Hubrig

Mikulášek

González

et al. 2010

A&A

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Context. Despite the importance of magnetic fields to a full understanding of the properties of accreting Herbig Ae/Be stars, these fields have scarcely been studied until now over the rotation cycle. One reason for the paucity of these observations is the lack of knowledge of their rotation periods. The sharp-lined young Herbig Ae star HD 101412 with a strong surface magnetic field has become in the past few years one of the most well-studied targets among the Herbig Ae/Be stars. Aims. We present our multi-epoch polarimetric spectra of this star acquired with FORS 2 to search for a rotation period and constrain the geometry of the magnetic field. Methods. We measured longitudinal magnetic fields for 13 different epochs distributed over 62 days. These new measurements and our previous measurements of the magnetic field in this star were combined with available photometric observations to determine the rotation period. Results. We find the rotation period to be P = 42.076 ± 0.017 d. According to near-infrared imaging studies, the star is observed nearly edge-on. The star exhibits a single-wave variation in the longitudinal magnetic field during the stellar rotation cycle. These observations are usually considered as evidence of a dominant dipolar contribution to the magnetic field topology.

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“…Between a tenth of a day and 10 days their spectra are proportional to 1/f in amplitude (equivalent to β=1, see Section 5.5), similar to our median Class II spectra, before flattening out again at longer periods. Interestingly the Fourier spectrum of the Herbig Ae star HD 37806 by Rucinski et al (2010) also shows a break at 1.5 days which may be a rotation period and again an amplitude proportional to 1/f below this. In contrast Rucinski et al (2008) and Siwak et al (2016) found a 'flicker noise' spectrum in M OST data of TW Hya (between 0.1 and 10 days) and RU Lup (between 0.5 and 10 days).…”

Section: Previous Measurements Of β For Class IImentioning

confidence: 96%

Characterizing the i-band variability of YSOs over six orders of magnitude in time-scale

Sergison

Naylor

Littlefair

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present an i-band photometric study of over 800 young stellar objects in the OB association Cep OB3b, which samples timescales from 1 minute to ten years. Using structure functions we show that on all timescales (τ ) there is a monotonic decrease in variability from Class I to Class II through the transition disc (TD) systems to Class III, i.e. the more evolved systems are less variable. The Class Is show an approximately power-law increase (τ 0.8 ) in variability from timescales of a few minutes to ten years. The Class II, TDs and Class III systems show a qualitatively different behaviour with most showing a power-law increase in variability up to a timescale corresponding to the rotational period of the star, with little additional variability beyond that timescale. However, about a third of the Class IIs show lower overall variability, but their variability is still increasing at 10 years. This behaviour can be explained if all Class IIs have two primary components to their variability. The first is an underlying roughly power-law variability spectrum, which evidence from the infrared suggests is driven by accretion rate changes. The second component is approximately sinusoidal and results from the rotation of the star. We suggest that the systems with dominant longer-timescale variability have a smaller rotational modulation either because they are seen at low inclinations or have more complex magnetic field geometries.We derive a new way of calculating structure functions for large simulated datasets (the "fast structure function"), based on fast Fourier transforms.

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Photometric variability of the Herbig Ae star HD 37806

Cited by 15 publications

References 33 publications

Characterising the magnetic fields of the Herbig Ae/Be stars HD 97048, HD 150193, HD 176386, and MWC 480

Characterising the magnetic fields of the Herbig Ae/Be stars HD 97048, HD 150193, HD 176386, and MWC 480

Rotationally modulated variations and the mean longitudinal magnetic field of the Herbig Ae star HD 101412

Characterizing the i-band variability of YSOs over six orders of magnitude in time-scale

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