X-ray emission from T Tauri stars and the role of accretion: inferences from the XMM-Newton extended survey of the Taurus molecular cloud

By A. Telleschi, M. Gudel, K. Briggs, M. Audard, F. Palla. 2006

153 citations recorded by the source corpus.

Context. T Tau stars display di erent X-ray properties depending on whether they are accreting (classical T Tau stars; CTTS) or not (weak-line T Tau stars; WTTS). X-ray properties may provide insight into the accretion process between disk and stellar surface. Aims. We use data from the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST) to study di erences in X-ray properties between CTTS and WTTS. Methods. XEST data are used to perform correlation and regression analysis between X-ray parameters and stellar properties. Results. We confirm the existence of a X-ray luminosity (LX) vs. mass (M) relation, LX/ M 1:69 0:11 , but this relation is a consequence of X-ray saturation and a mass vs. bolometric luminosity (L ) relation for the TTS with an average age of 2.4 Myr. X-ray saturation indicates LX= constL , although the constant is di erent for the two subsamples: const= 10 3:73 0:05 for CTTS and const= 10 3:39 0:06 for WTTS. Given a similar L distribution of both samples, the X-ray luminosity function also reflects a real X-ray deficiency in CTTS, by a factor of 2 compared to WTTS. The average electron temperatures Tav are correlated with LX in WTTS but not in CTTS; CTTS sources are on average hotter than WTTS sources. At best marginal dependencies are found between X-ray properties and mass accretion rates or age. Conclusions. The most fundamental properties are the two saturation laws, indicating suppressed LX for CTTS. We speculate that some of the accreting material in CTTS is cooling active regions to temperatures that may not significantly emit in the X-ray band, and if they do, high-resolution spectroscopy may be required to identify lines formed in such plasma, while CCD cameras do not detect these components. The similarity of the LX vs. Tav dependencies in WTTS and main-sequence stars as well as their similar X-ray saturation laws suggests similar physical processes for the hot plasma, i.e., heating and radiation of a magnetic corona.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/67fecd05f839b8b32f95526e834c6768e0620b91

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In Astronomy and Astrophysics

1. M. Gudel
2. K. Luhman
3. Eric Mamajek
4. P. R. Allen
5. Kelle Cruz
6. L. Hillenbrand
7. J. Drake
8. N. Wright

In Instrumentation

1. K. Luhman
2. M. Gudel
3. P. R. Allen
4. Eric Mamajek
5. Kelle Cruz
6. Eric D. Feigelson
7. Y. Nazé
8. N. Wright

Citations in the corpus

• THE STELLAR-ACTIVITY–ROTATION RELATIONSHIP AND THE EVOLUTION OF STELLAR DYNAMOS (2011, background): “The most Xray luminous of single, low-mass stars have been found to be the youngest, where X-ray luminosity levels of LX/Lbol ∼ 10 −3 are common (e.g. Telleschi et al. 2007), though close or interacting binary stars such as RS CVns may also reach such levels.”
• The Sun in Time: Activity and Environment (2007, methodology): “Telleschi et al. (2007b) removed this trend from the Taurus sample.”
• X-ray spectroscopy of stars (2009, background): “Considering all X-ray properties of ABur, Telleschi et al (2007c) suggested the presence of magnetically confined winds shock.”
• Highlights from the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST) (2006, background): “The Reflection Grating Spectrometers (den Herder et al. 2001) secured sufficiently good spectra of four CTTS, four WTTS, and one Herbig star, making this by far the largest co- herent sample of high-resolution X-ray spectra of TTS available at the time (Telleschi et al. 2007b).”
• AN INFRARED/X-RAY SURVEY FOR NEW MEMBERS OF THE TAURUS STAR-FORMING REGION (2009, background): “According to Figure 11, the completeness of XEST decreases for lower stellar masses and earlier SED classes, which is a reflection of the fact that X-ray emission is correlated with both of these properties (Telleschi et al. 2007; Prisinzano et al. 2008).”
• The Stellar Population of the Chamaeleon I Star-forming Region (2007, methodology): “If ESO Hα 569 has an X-ray luminosity in the range of values observed for classical T Tauri stars at masses of 0.4 M⊙ (Telleschi et al. 2007), then the detection limit described by Feigelson & Lawson (2004) indicates an extinction of AK & 60 toward this star.”