Intercombinational line profiles in the UV spectra of T Tauri stars and analysis of the accretion zone

Ламзин, С. А.

doi:10.1134/1.163855

Cited by 25 publications

(56 citation statements)

References 6 publications

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“…ABWVJ02 indicate that lines with these velocity widths could be formed in the preshock region, as proposed by Lamzin (2000). However, this interpretation cannot explain centroids at nearly zero velocities, as also noted by ABWVJ02, and cannot explain the origin of the extended blue wings of the lines, since the preshock region is fairly narrow (CG98) and blueshifted emission would be hidden by the star (see Lamzin 2003). On the other hand, broad line profiles centered near zero velocities are characteristic of magnetospheric accretion ( Muzerolle et al 2001; x 4.2).…”

Section: Accretion Origg In Of the Ultravv Iolet Linesmentioning

confidence: 73%

“…High-resolution observations of the C iv k1548 and Si iv k1403 line profiles in CTTSs by ABWVJ02 show line widths of the order of several hundred kilometers per second, at low velocities. ABWVJ02 indicate that lines with these velocity widths could be formed in the preshock region, as proposed by Lamzin (2000). However, this interpretation cannot explain centroids at nearly zero velocities, as also noted by ABWVJ02, and cannot explain the origin of the extended blue wings of the lines, since the preshock region is fairly narrow (CG98) and blueshifted emission would be hidden by the star (see Lamzin 2003).…”

Section: Accretion Origg In Of the Ultravv Iolet Linesmentioning

confidence: 87%

“…Previous studies have explored the relationship between UV emission-line fluxes and accretion , hereafter JVL00; ABWVJ02; Kravtsova & Lamzin 2002Lamzin 2003) We continue these studies here with the advantage of having simultaneous line fluxes and estimates of the accretion properties, in addition to a consistent determination of reddening for each star.…”

Section: Accretion Origg In Of the Ultravv Iolet Linesmentioning

confidence: 97%

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The Mass Accretion Rates of Intermediate-Mass T Tauri Stars

Calvet¹,

Muzerolle²,

Briceño³

et al. 2004

409

537

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We present Hubble Space Telescope ultraviolet spectra and supporting ground-based data for a sample of nine intermediate-mass T Tauri stars (IMTTSs; 1.5-4 M ). The targets belong to three star-forming regions: T Tau, SU Aur, and RY Tau in the Taurus clouds; EZ Ori, P2441, and V1044 Ori in the Ori OB1c association surrounding the Orion Nebula cluster; and CO Ori, GW Ori, and GX Ori in the ring around k Ori. The supporting groundbased observations include nearly simultaneous UBV(R I ) C photometry, 6 8 resolution spectra covering the range 3900-7000 8, optical echelle observations in the range 5800-8600 8, and K-band near-infrared spectra. We use these data to determine improved spectral types and reddening corrections and to obtain physical parameters of the targets. We find that an extinction law with a weak 2175 8 feature but high values of A UV =A V is required to explain the simultaneous optical-UV data; the reddening laws for two B-type stars located behind the Taurus clouds, HD 29647 and HD 283809, meet these properties. We argue that reddening laws with these characteristics may well be representative of cold, dense molecular clouds. Spectral energy distributions and emission-line profiles of the IMTTSs are consistent with expectations from magnetospheric accretion models. We compare our simultaneous optical-UV data with predictions from accretion shock models to get accretion luminosities and mass accretion rates (Ṁ ) for the targets. We find that the average mass accretion rate for IMTTSs is $3 ; 10 À8 M yr À1 , a factor of $5 higher than that for their low-mass counterparts. The new data extend the correlation betweenṀ and stellar mass to the intermediate-mass range. Since the IMTTSs are evolutionary descendants of the Herbig Ae/ Be stars, our results put limits to the mass accretion rates of their disks. We present luminosities of the UV lines of highly ionized metals and show that they are well above the saturation limit for magnetically active cool stars but correlate strongly with accretion luminosity, indicating that they are powered by accretion, in agreement with previous claims but using a sample in which reddening and accretion luminosities have been determined self-consistently. Finally, we find that the relation between accretion luminosity and Br luminosity found for low-mass T Tauri stars extends to the intermediate-mass regime.

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Section: Accretion Origg In Of the Ultravv Iolet Linesmentioning

confidence: 73%

Section: Accretion Origg In Of the Ultravv Iolet Linesmentioning

confidence: 87%

Section: Accretion Origg In Of the Ultravv Iolet Linesmentioning

confidence: 97%

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The Mass Accretion Rates of Intermediate-Mass T Tauri Stars

Calvet¹,

Muzerolle²,

Briceño³

et al. 2004

409

537

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“…However, it cools rapidly in the radiative zone behind the shock wave, and no reverse flow into the wind is expected (e.g. Lamzin 1998;Koldoba et al 2008). In another investigation, however, Alfvén waves and other processes at the stellar surface help accelerate up to 1 per cent of the accreting disc matter into the wind (e.g.…”

Section: Matter Loading On To Stellar Field Lines and Possible Role Omentioning

confidence: 99%

Launching of conical winds and axial jets from the disc��magnetosphere boundary: axisymmetric and 3D simulations

Romanova

Ustyugova

Koldoba

et al. 2009

Monthly Notices of the Royal Astronomical Society

216

268

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We investigate the launching of outflows from the disc–magnetosphere boundary of slowly and rapidly rotating magnetized stars using axisymmetric and exploratory 3D magnetohydrodynamic simulations. We find long‐lasting outflows in the following cases. (1) In the case of slowly rotating stars, a new type of outflow, a conical wind, is found and studied in simulations. The conical winds appear in cases where the magnetic flux of the star is bunched up by the disc into an X‐type configuration. The winds have the shape of a thin conical shell with a half‐opening angle θ∼ 30°–40°. About 10–30 per cent of the disc matter flows from the inner disc into the conical winds. The conical winds may be responsible for episodic as well as long‐lasting outflows in different types of stars. There is also a low‐density, higher velocity component (a jet) in the region inside the conical wind. (2) In the case of rapidly rotating stars (the ‘propeller regime’), a two‐component outflow is observed. One component is similar to the conical winds. A significant fraction of the disc matter may be ejected into the winds. The second component is a high‐velocity, low‐density magnetically dominated axial jet where matter flows along the opened polar field lines of the star. The jet has a mass flux of about 10 per cent of that of the conical wind, but its energy flux (dominantly magnetic) can be larger than the energy flux of the conical wind. The jet's angular momentum flux (also dominantly magnetic) causes the star to spin down rapidly. Propeller‐driven outflows may be responsible for the jets in protostars and for their rapid spin‐down. The jet is collimated by the magnetic force while the conical winds are only weakly collimated in the simulation region. Exploratory 3D simulations show that conical winds are axisymmetric about the rotational axis (of the star and the disc), even when the dipole field of the star is significantly misaligned.

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“…But an additional averaging of the specific intensity over θ makes it impossible, in principle, to derive more accurate accretion shock parameters within the frame of the GC98 model. In contrast our approach gives the possibility to derive N 0 and V 0 values in each point of the accretion zone as well as its geometry if we succeed in observing the star at different phases of the rotational period (Lamzin 2000c).…”

Section: Accretion Flow Parametersmentioning

confidence: 99%

UV spectra of T Tauri stars from the HST and IUE satellites: BP Tau

Errico

Ламзин²,

Vittone

2001

A&A

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Abstract. Ultraviolet spectra of BP Tau observed with HST/GHRS and IUE satellites were analysed. We found that BP Tau activity can be explained in the frame of a disk accretion model if we assume that the stellar magnetic axis is strongly inclined to the disk plane. The following set of accretion process parameters were derived: relative surface area of the accretion zone f 0.25, accretion rateṀac 3.6 × 10 −8 M yr −1 , accretion energy flux F = 2.3 × 10 10 erg s −1 cm −2 and accretion luminosity Lac 0.37 L . The relevance of these parameters is discussed. We argue that the Calvet & Gullbring (1998) accretion shock model is too crude to believe that the accretion spot surface area is indeed proportional to the square of the accretion rate, as Ardila & Basri (2000) found through this model. A strong flare in the Fe ii 2811.8, 2812.1Å lines was detected, it was probably produced by an increase of the accretion rate. During the flare, the accretion luminosity was comparable to or even larger than the stellar bolometric luminosity.

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Intercombinational line profiles in the UV spectra of T Tauri stars and analysis of the accretion zone

Cited by 25 publications

References 6 publications

The Mass Accretion Rates of Intermediate-Mass T Tauri Stars

The Mass Accretion Rates of Intermediate-Mass T Tauri Stars

Launching of conical winds and axial jets from the disc��magnetosphere boundary: axisymmetric and 3D simulations

UV spectra of T Tauri stars from the HST and IUE satellites: BP Tau

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Intercombinational line profiles in the UV spectra of T Tauri stars and analysis of the accretion zone

Cited by 25 publications

References 6 publications

The Mass Accretion Rates of Intermediate-Mass T Tauri Stars

The Mass Accretion Rates of Intermediate-Mass T Tauri Stars

Launching of conical winds and axial jets from the disc���magnetosphere boundary: axisymmetric and 3D simulations

UV spectra of T Tauri stars from the HST and IUE satellites: BP Tau

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Product

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Launching of conical winds and axial jets from the disc��magnetosphere boundary: axisymmetric and 3D simulations