Dynamics of the circumstellar gas in the Herbig Ae stars BF Orionis, SV Cephei, WW Vulpeculae and XY Persei

Mora, A.; Eiroa, C.; Natta, A.; Grady, C. A.; Winter, D. de; Davies, John K.; Ferlet, R.; Harris, A. W.; Miranda, L. F.; Montesinos, B.; Oudmaijer, R. D.; Palacios, Joaquín García; Quirrenbach, A.; Rauer, H.; Alberdi, A.; Cameron, A. Collier; Deeg, H. J.; Garzón, F.; Horne, K.; Merın, Bruno; Penny, A. J.; Schneider, Jodi; Solano, E.; Tsapras, Y.; Wesselius, P. R.

doi:10.1051/0004-6361:20040096

Cited by 26 publications

(40 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many TACs observed are similar to those studied by Natta et al (2000) and Mora et al (2002Mora et al ( , 2004 in similar age Herbig Ae stars. These authors propose magnetospheric accretion of primordial gas as the most likely origin.…”

Section: Utrecht Echelle Spectrograph (Ues) On the William Herschelsupporting

confidence: 82%

Gas modelling in the disc of HD 163296

Tilling¹,

Woitke²,

Meeus³

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of ∼4 Myr, with evidence of a circumstellar disc extending out to ∼540 AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (GAS in Protoplanetary Systems), consisting of a detection of the [Oi] 63 μm line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the 12 CO 3-2, 2-1 and 13 CO J = 1-0 line transitions, as well as an upper limit for the H 2 0-0 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry.

show abstract

Section: Utrecht Echelle Spectrograph (Ues) On the William Herschelsupporting

confidence: 82%

Gas modelling in the disc of HD 163296

Tilling¹,

Woitke²,

Meeus³

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…The differences between lines were consistent with the differences in density and temperature expected along one or more extended (∼0.1 AU) accretion columns or non-axisymmetric rotating/infalling structures (SA12). A similar approach, but using absorption lines, has been used to track cold matter moving around intermediate-mass stars (Mora et al 2002(Mora et al , 2004, and to trace the physical conditions along the accretion column in S CrA SE (Petrov et al 2014). With the time coverage we now have for EX Lupi in quiescence, we can explore the physical properties and also use the time variable to explore the dynamics of the accretion columns.…”

Section: Introductionmentioning

confidence: 99%

Accretion dynamics of EX Lupi in quiescence

Sicilia‐Aguilar¹,

Fang²,

Roccatagliata³

et al. 2015

A&A

View full text Add to dashboard Cite

Context. EX Lupi is a young, accreting M0 star and the prototype of EXor variable stars. Its spectrum is very rich in emission lines, including many metallic lines with narrow and broad components. The presence of a close companion has also been proposed, based on radial velocity signatures. Aims. We use the metallic emission lines to study the accretion structures and to test the companion hypothesis. Methods. We analyse 54 spectra obtained during five years of quiescence time. We study the line profile variability and the radial velocity of the narrow and broad metallic emission lines. We use the velocity signatures of different species with various excitation conditions and their time dependency to track the dynamics associated with accretion. Results. We observe periodic velocity variations in the broad and the narrow line components, consistent with rotational modulation. The modulation is stronger for lines with higher excitation potentials (e.g. He II), which are likely produced in a confined area very close to the accretion shock. Conclusions. We propose that the narrow line components are produced in the post-shock region, while the broad components originate in the more extended, pre-shock material in the accretion column. All the emission lines suffer velocity modulation due to the rotation of the star. The broad components are responsible for the line-dependent veiling observed in EX Lupi. We demonstrate that a rotationally modulated line-dependent veiling can explain the radial velocity signature of the photospheric absorption lines, making the close-in companion hypothesis unnecessary. The accretion structure is locked to the star and very stable during the five years of observations. Not all stars with similar spectral types and accretion rates show the same metallic emission lines, which could be related to differences in temperature and density in their accretion structure(s). The contamination of photospheric signatures by accretion-related processes can be turned into a very useful tool for determining the innermost details of the accretion channels in the proximity of the star. The presence of emission lines from very stable accretion columns will nevertheless be a very strong limitation for the detection of companions by radial velocity in young stars, given the similarity of the accretion-related signatures with those produced by a companion.

show abstract

“…The spectroscopic monitoring of some sources (see e.g. Praderie et al 1986;Pogodin 1994;Rodgers et al 2002;Mora et al 2002Mora et al , 2004 revealed that the spectra of HAeBe objects are not only characterized by the presence of emission lines, but also by the complex variations observed in both the emission and absorption features. This variability is also characteristic of T-Tauri stars (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Optical spectroscopic variability of Herbig Ae/Be stars

Mendigutía

Eiroa

Montesinos

et al. 2011

A&A

Self Cite

View full text Add to dashboard Cite

Aims. In order to gain insights into the variability behaviour of the circumstellar (CS) atomic gas, we have analysed 337 multi-epoch optical spectra of 38 Herbig Ae/Be (HAeBe) stars. Methods. Equivalent widths (EWs) and line fluxes of the Hα, [O i]6300, He i5876 and Na iD lines were obtained for each spectrum; the Hα line width at 10% of peak intensity (W 10 ) and profile shapes were also measured and classified. The mean line strengths and relative variabilities were quantified for each star. Simultaneous optical photometry was used to estimate the line fluxes.Results. We present a homogeneous spectroscopic database of HAeBe stars. The lines are variable in practically all stars and timescales, although 30% of the objects show a constant EW in [O i]6300, which is also the only line that shows no variability on timescales of hours. The He i5876 and Na iD EW relative variabilities are typically the largest, followed by those in [O i]6300 and Hα. The EW changes can be larger than one order of magnitude for the He i5876 line, and up to a factor 4 for Hα. The [O i]6300 and Hα EW relative variabilities are correlated for most stars in the sample. The Hα mean EW and W 10 are uncorrelated, as are their relative variabilities. The Hα profile changes in ∼70% of the objects. The massive stars in the sample (M * > 3 M ) usually show more stable Hα profiles with blueshifted self-absorptions and less variable 10% widths. Conclusions. Our data suggest multiple causes for the different line variations, but the [O i]6300 and Hα variability must share a similar origin in many objects. The physical mechanism responsible for the Hα line broadening does not depend on the amount of emission; unlike in lower-mass stars, physical properties based on the Hα luminosity and W 10 would significantly differ. Our results provide additional support to previous works that reported different physical mechanisms in Herbig Ae and Herbig Be stars. The multi-epoch observations we present are a useful tool for understanding the origin of the CS lines and their variability, and to establish distinctions in the physical processes operating in pre-main sequence stars.

show abstract

Dynamics of the circumstellar gas in the Herbig Ae stars BF Orionis, SV Cephei, WW Vulpeculae and XY Persei

Cited by 26 publications

References 19 publications

Gas modelling in the disc of HD 163296

Gas modelling in the disc of HD 163296

Accretion dynamics of EX Lupi in quiescence

Optical spectroscopic variability of Herbig Ae/Be stars

Contact Info

Product

Resources

About