MN Lup: X-RAYS FROM A WEAKLY ACCRETING T TAURI STAR

Günther, H. M.; Wolter, Uwe; Robrade, J.; Wolk, S. J.

doi:10.1088/0004-637x/771/1/70

Cited by 6 publications

(3 citation statements)

References 77 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such static behavior differs from high-lying stellar prominences found in rapidly rotating stars such as AB Dor (Collier Cameron & Robinson 1989) and in rapidly rotating T Tauri stars (Oliveira et al 2000;Skelly et al 2008;Günther et al 2013) where the absorption feature moves rapidly in velocity from negative to positive (or vice versa) as the feature traverses the stellar disk. The absorption features in TW Hya are stable in velocity for hours, and are not at all similar to the moving Discrete Absorption Components (DACs) observed in the winds of O stars (cf.…”

Section: Detection Of Shadowing By Accretion Funnelsmentioning

confidence: 73%

STRUCTURE AND DYNAMICS OF THE ACCRETION PROCESS AND WIND IN TW Hya

Dupree

Brickhouse

Cranmer

et al. 2014

ApJ

View full text Add to dashboard Cite

Time-domain spectroscopy of the classical accreting T Tauri star, TW Hya, covering a decade and spanning the far UV to the near-infrared spectral regions can identify the radiation sources, the atmospheric structure produced by accretion, and properties of the stellar wind. On time scales from days to years, substantial changes occur in emission line profiles and line strengths. Our extensive time-domain spectroscopy suggests that the broad near-IR, optical, and far-uv emission lines, centered on the star, originate in a turbulent post-shock region and can undergo scattering by the overlying stellar wind as well as some absorption from infalling material. Stable absorption features appear in Hα, apparently caused by an accreting column silhouetted in the stellar wind. Inflow of material onto the star is revealed by the near-IR He I 10830Å line, and its free-fall velocity correlates inversely with the strength of the post-shock emission, consistent with a dipole accretion model. However, the predictions of hydrogen line profiles based on accretion stream models are not well-matched by these observations. Evidence of an accelerating warm to hot stellar wind is shown by the near-IR He I line, and emission profiles of C II, C III, C IV, N V, and O VI. The outflow of material changes substantially in both speed and opacity in the yearly sampling of the near-IR He I line over a decade. Terminal outflow velocities that 2 Fred L. Whipple Observatory, Amado, AZ 3 Michigan State University, East Lansing, MI range from 200 km s −1 to almost 400 km s −1 in He I appear to be directly related to the amount of post-shock emission, giving evidence for an accretion-driven stellar wind. Calculations of the emission from realistic post-shock regions are needed.

show abstract

Section: Detection Of Shadowing By Accretion Funnelsmentioning

confidence: 73%

STRUCTURE AND DYNAMICS OF THE ACCRETION PROCESS AND WIND IN TW Hya

Dupree

Brickhouse

Cranmer

et al. 2014

ApJ

View full text Add to dashboard Cite

show abstract

“…We also note that one Class III YSO was found to have a ∼1 MK plasma component, demonstrating that processes other than accretion (e.g., coronal activitiy) may also contribute to soft X-ray fluxes from YSOs. However, in the absence of Hα spectroscopy, we cannot exclude the possibility that this system is actively accreting gas, despite a lack of thermal IR excess due to circumstellar dust (Günther et al 2013).…”

Section: L1630 Ysos X-ray Spectral Characteristicsmentioning

confidence: 95%

Star Formation in Orion's L1630 Cloud: An Infrared and Multi-Epoch X-Ray Study

Principe

Kastner

Grosso

et al. 2014

ApJS

View full text Add to dashboard Cite

X-ray emission is characteristic of young stellar objects (YSOs) and is known to be highly variable. We investigate, via an infrared and multi-epoch X-ray study of the L1630 dark cloud, whether and how X-ray variability in young stellar objects is related to protostellar evolutionary state. We have analyzed 11 Chandra X-ray Observatory observations, obtained over the course of four years and totaling ∼240 ks exposure time, targeting the eruptive Class I YSO V1647 Ori in L1630. We used 2MASS and Spitzer data to identify and classify IR counterparts to L1630 X-ray sources and identified a total of 52 X-ray emitting YSOs with IR counterparts, including 4 Class I sources and 1 Class 0/I source. We have detected cool (< 3 MK) plasma, possibly indicative of accretion shocks, in three classical T Tauri stars. A subsample of 27 X-ray-emitting YSOs were covered by 9 of the 11 Chandra observations targeting V1647 Ori and vicinity. For these 27 YSOs, we have constructed X-ray light curves spanning approximately four years. These light curves highlight the variable nature of pre-main sequence X-ray emitting young stars; many of the L1630 YSOs vary by orders of magnitude in count rate between observations. We discuss possible scenarios to explain apparent trends between various X-ray spectral properties, X-ray variance and YSO classification.

show abstract

“…A soft X-ray excess and wide Hα wings were detected as evidence for accretion. This object is expected to be going through a very short lived phase in which the disk is optically thin and the last of the gas is accreting (Guenther et al 2013).…”

Section: Introductionmentioning

confidence: 99%

THE EVOLUTION OF ACCRETION IN YOUNG STELLAR OBJECTS: STRONG ACCRETORS AT 3-10 Myr

Ingleby

Calvet

Hernández³

et al. 2014

ApJ

View full text Add to dashboard Cite

While the rate of accretion onto T Tauri stars is predicted to decline with age, objects with strong accretion have been detected up to ages of 10 Myr. We analyze a sample of these old accretors identified by having a significant U band excess and infrared emission from a circumstellar disk. Objects were selected from the ∼3 Myr σ Ori, 4-6 Myr Orion OB1b and 7-10 Myr Orion OB1a star forming associations. We use high resolution spectra from the Magellan Inamori Kyocera Echelle to estimate the veiling of absorption lines and calculate extinction for our T Tauri sample. We also use observations, obtained with the Magellan Echellette and in a few cases the SWIFT Ultraviolet and Optical Telescope, to estimate the excess produced in the accretion shock, which is then fit with accretion shock models to estimate the accretion rate. We find that even objects as old as 10 Myr may have high accretion rates, up to ∼10 −8 M ⊙ yr −1 . These objects cannot be explained by viscous evolution models, which would deplete the disk in shorter timescales, unless the initial disk mass is very high, a situation which is unstable. We show that the infrared spectral energy distribution of one object, CVSO 206, does not reveal evidence of significant dust evolution, which would be expected during the 10 Myr lifetime. We compare this object to predictions from photoevaporation and planet formation models and suggest that neither of these processes have had a strong impact on the disk of CVSO 206.

show abstract

MN Lup: X-RAYS FROM A WEAKLY ACCRETING T TAURI STAR

Cited by 6 publications

References 77 publications

STRUCTURE AND DYNAMICS OF THE ACCRETION PROCESS AND WIND IN TW Hya

STRUCTURE AND DYNAMICS OF THE ACCRETION PROCESS AND WIND IN TW Hya

Star Formation in Orion's L1630 Cloud: An Infrared and Multi-Epoch X-Ray Study

THE EVOLUTION OF ACCRETION IN YOUNG STELLAR OBJECTS: STRONG ACCRETORS AT 3-10 Myr

Contact Info

Product

Resources

About