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We present the analysis of 16 classical T Taur stars using LAMOST and TESS data, investigating spectral properties, photometric variations, and mass-accretion rates. All 16 stars exhibit emissions in H$\alpha$ lines, from which the average…

Solar and Stellar Astrophysics · Physics 2023-08-03 Chia-Lung Lin , Wing-Huen Ip , Yao Hsiao , Tzu-Hueng Chang , Yi-han Song , A-Li Luo

Diagnostics of electron temperature (T_e), electron density (n_e), and hydrogen column density (N_H) from the Chandra High Energy Transmission Grating spectrum of He-like Ne IX in TW Hydrae (TW Hya), in conjunction with a classical…

Solar and Stellar Astrophysics · Physics 2015-06-12 N. S. Brickhouse , S. R. Cranmer , A. K. Dupree , H. M. Günther , G. J. M. Luna , S. J. Wolk

From a long time series of high resolution (R=115,000) HARPS spectra and simultaneous broad-band photometry, we report new evidence for magnetospheric accretion as well as ejection processes in the nearly edge-on classical T Tauri star AA…

We present initial result of a large spectroscopic survey aimed at measuring the timescale of mass accretion in young, pre-main-sequence stars in the spectral type range K0 - M5. Using multi-object spectroscopy with VIMOS at the VLT we…

Solar and Stellar Astrophysics · Physics 2015-05-14 D. Fedele , M. E. van den Ancker , Th. Henning , R. Jayawardhana , J. M. Oliveira

The dependence of the mass accretion rate on the stellar properties is a key constraint for star formation and disk evolution studies. Here we present a study of a sample of stars in the Chamaeleon I star forming region carried out using…

We present an optical/near-IR survey of 11 variable young stars (EXors and EXor candidates) aimed at deriving and monitoring their accretion properties. About 30 optical and near-infrared spectra ($\Re$ $\sim$ 1500-2000) were collected…

Solar and Stellar Astrophysics · Physics 2022-04-27 T. Giannini , A. Giunta , M. Gangi , R. Carini , D. Lorenzetti , S. Antoniucci , A. Caratti o Garatti , L. Cassarà , B. Nisini , A. Rossi , V. Testa , F. Vitali

The mass accretion rate is the fundamental parameter to understand the process of mass assembly that results in the formation of a low-mass star. This parameter has been largely studied in Classical TTauri stars in star-forming regions with…

Characterising stellar jet asymmetries is key to setting robust constraints on jet launching models and improving our understanding of the underlying mechanisms behind jet launching. We aim to characterise the asymmetric properties of the…

Solar and Stellar Astrophysics · Physics 2024-12-11 A. Murphy , E. T. Whelan , F. Bacciotti , D. Coffey , F. Comerón , J. Eislöffel , B. Nisini , S. Antoniucci , J. M. Alcalá , T. P. Ray

We report the first comprehensive study of emission line variability in an accreting young brown dwarf. We have collected 14 high-resolution optical spectra of 2MASSW J1207334-393254 (M8), a likely member of the nearby 8-million-year-old TW…

Astrophysics · Physics 2009-11-13 Alexander Scholz , Ray Jayawardhana , Alexis Brandeker

Emission lines indicative of active accretion have been seen on a handful of low-mass companions (M < 30 MJup) to stars. Line variability is ubiquitous on stellar accretors but has never been characterized in detail on low-mass companions…

Young stars exhibit short-term photometric variability caused by mass accretion events from circumstellar disks, the presence of dusty warps within the inner disks, starspots that rotate across the stellar surfaces, and flares. Long-term…

Stars may be assembled in large growth spurts, however the evidence for this hypothesis is circumstantial. Directly studying the accretion at the earliest phases of stellar growth is challenging because young stars are deeply embedded in…

Solar and Stellar Astrophysics · Physics 2015-06-12 Doug Johnstone , Benjamin Hendricks , Gregory J. Herczeg , Simon Bruderer

Differences have been reported between the X-ray emission of accreting and non-accreting stars. Some observations have suggested that accretion shocks could be responsible for part of the X-ray emission in Classical T Tauri stars (CTTS). We…

Astrophysics · Physics 2009-11-11 A. Telleschi , M. Guedel , K. R. Briggs , M. Audard , L. Scelsi

The temporal decay of mass accretion in young stars is a fundamental tracer of the early evolution of circumstellar disks. Through population syntheses, we study how correlated uncertainties between the estimated parameters of young stars…

Solar and Stellar Astrophysics · Physics 2015-06-18 Nicola Da Rio , Rob D. Jeffries , Carlo F. Manara , Massimo Robberto

We developed a grid of stellar rotation models for low-mass and solar-type Classical T Tauri stars (CTTS) ($0.3M_{\odot}<M_{\ast}<1.2M_{\odot}$). These models incorporate the star-disk interaction and magnetospheric ejections to investigate…

We present multiple epochs of near-IR spectroscopy for a sample of 25 young stars, including T Tauri, Herbig Ae/Be, and FU Ori objects. Using the FSPEC instrument on the Bok 90-inch telescope, we obtained K-band spectra of the BrGamma…

Solar and Stellar Astrophysics · Physics 2015-06-23 J. A. Eisner , G. H. Rieke , M. J. Rieke , K. M. Flaherty , Jordan M. Stone , T. J. Arnold , S. R. Cortes , E. Cox , C. Hawkins , A. Cole , S. Zajac , A. L. Rudolph

(Abridged) Optical spectra of classical T Tauri stars (cTTS) are rich in emission lines of low-excitation species that are composed of narrow and broad components, related to two regions with different kinematics, densities, and…

Solar and Stellar Astrophysics · Physics 2015-05-30 P. P. Petrov , G. F. Gahm , H. C. Stempels , F. M. Walter , S. A. Artemenko

We present the results of a near-IR spectroscopic analysis on 3 young embedded sources (HH26IRS, HH34IRS and HH46IRS) belonging to different star-forming regions and displaying well developed jet structures. The aim is to investigate the…

Astrophysics · Physics 2009-11-13 S. Antoniucci , B. Nisini , T. Giannini , D. Lorenzetti

Classical T Tauri stars are low-mass pre-main sequence stars with an active circumstellar environment. In this work we present the identification and study of 260 Classical T Tauri stars using LAMOST Data Release 6, among which 104 stars…

Solar and Stellar Astrophysics · Physics 2023-08-02 S. Nidhi , Blesson Mathew , B. Shridharan , Suman Bhattacharyya , Edwin Das , Sreeja S Kartha

The coevolution of T Tauri stars and their surrounding protoplanetary disks dictates the timescales of planet formation. In this paper, we present magnetospheric accretion and inner disk wall model fits to NUV-NIR spectra of nine classical…

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