Magnetic topologies of young suns: the weak-line T Tauri stars TWA 6 and TWA 8A

Hill, C. A.; Folsom, C. P.; Donati, J.‐F.; Herczeg, Gregory J.; Hussain, G. A. J.; Alencar, S. H. P.; Gregory, S. G.

doi:10.1093/mnras/stz403

Cited by 33 publications

(27 citation statements)

References 84 publications

(138 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Coronal TTS X-ray emission indicates the presence of a strong surface magnetic field (Stassun et al 2006(Stassun et al , 2007. The typical mean-field strengths measured at the surface of classical (fully convective) TTS are 1-3 kG, and decrease to a few 100 G for weak-line (mainly radiative) TTS (Hill et al 2019;Villebrun et al 2019;Donati et al 2019;Sokal et al 2020). The dynamos producing these magnetic fields are driven by convective interior structure, typical of low-mass TTS evolving along Hayashi tracks.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the X-Ray Emission of Intermediate-mass Pre-main-sequence Stars

Nuñez

Povich

Binder

et al. 2021

View full text Add to dashboard Cite

We use X-ray and infrared observations to study the properties of three classes of young stars in the Carina Nebula: intermediate-mass (2-5 M e ) pre-main-sequence stars (IMPS; i.e., intermediate-mass T Tauri stars), late-B and A stars on the zero-age main sequence (AB), and lower-mass T Tauri stars (TTS). We divide our sources among these three subclassifications and further identify disk-bearing young stellar objects versus diskless sources with no detectable infrared (IR) excess emission using IR (1-8 μm) spectral energy distribution modeling. We then perform X-ray spectral fitting to determine the hydrogen-absorbing column density (N H ), absorption-corrected X-ray luminosity (L X ), and coronal plasma temperature (kT) for each source. We find that the X-ray spectra of both IMPS and TTS are characterized by similar kT and N H , and on average L X /L bol ∼4×10 −4 . IMPS are systematically more luminous in X-rays (by ∼0.3 dex) than all other subclassifications, with median L X =2.5×10 31 erg s −1 , while AB stars of similar masses have X-ray emission consistent with TTS companions. These lines of evidence converge on a magnetocoronal flaring source for IMPS X-ray emission, a scaled-up version of the TTS emission mechanism. IMPS therefore provide powerful probes of isochronal ages for the first ∼10 Myr in the evolution of a massive stellar population, because their intrinsic, coronal X-ray emission decays rapidly after they commence evolving along radiative tracks. We suggest that the most luminous (in both X-rays and IR) IMPS could be used to place empirical constraints on the location of the intermediate-mass stellar birth line.

show abstract

Section: Introductionmentioning

confidence: 99%

Characterizing the X-Ray Emission of Intermediate-mass Pre-main-sequence Stars

Nuñez

Povich

Binder

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Bessolaz et al (2008) have studied the conditions for a steady accretion flow from a circumstellar disk in the presence of a dipolar stellar magnetic field. There are few measures of photospheric magnetic fields for low-mass (M * ≤ 0.5 M ) YSOs with typical values of B * ≈ 1 kG (e.g., Hill et al 2019;Lavail et al 2019), but fields of about 100 G and lower have also been observed (e.g., Donati et al 2010;Morin et al 2011). Based on Eq.…”

Section: Discussionmentioning

confidence: 99%

ISO-ChaI 52: a weakly accreting young stellar object with a dipper light curve

Frasca

Manara

Alcalá

et al. 2020

A&A

View full text Add to dashboard Cite

We report the discovery of periodic dips in the multiband light curve of ISO-ChaI 52, a young stellar object in the Chamaeleon I dark cloud. This is one of the peculiar objects that display very low or negligible accretion in their UV continuum and spectral lines, although they present a remarkable infrared excess emission characteristic of optically thick circumstellar disks. We have analyzed a spectrum obtained at the Very Large Telescope with the X-shooter spectrograph with the tool ROTFIT to determine the stellar parameters. The latter, along with photometry from our campaign with the Rapid Eye Mount telescope and from the literature, have allowed us to model the spectral energy distribution and to estimate the size and temperature of the inner and outer disk. Based on the rotational period of the star-disk system of 3.45 days, we estimate a disk inclination of 36°. The depth of the dips in different bands has been used to gain information about the occulting material. A single extinction law is not able to fit the observed behavior, while a two-component model of a disk warp composed of a dense region with a gray extinction and an upper layer with an extinction as in the interstellar medium provides a better fit to the data.

show abstract

“…However, see Koen (2016) for a discussion of the possibility of abovephotospheric spot temperatures in WTTS. Furthermore, the surface brightness reconstructions made with Zeeman Doppler imaging for WTTSs by Donati et al (2014Donati et al ( , 2015Donati et al ( , 2017 and Hill et al (2017Hill et al ( , 2019 indicate the presence of cool spots and warm plages at the stellar surface of young stars with convective envelopes. Thus, the warm spots found for V1598 Cyg do not provide conclusive evidence for the binary nature of the source.…”

Section: Spot Properties On V1598 Cygmentioning

confidence: 92%

A survey for variable young stars with small telescopes – III. Warm spots on the active star V1598 Cyg

Froebrich

Scholz

Eislöffel

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Magnetic spots on low-mass stars can be traced and characterised using multi-band photometric light curves. Here we analyse an extensive data set for one active star, V1598 Cyg, a known variable K dwarf which is either pre-main sequence and/or in a close binary system. Our light curve contains 2854 photometric data points, mostly in V, Rc, Ic, but also in U, B and Hα, with a total baseline of about 4 yr, obtained with small telescopes as part of the HOYS project. We find that V1598 Cyg is a very fast rotator with a period of 0.8246 days and varying amplitudes in all filters, best explained as a signature of strong magnetic activity and spots. We fit the photometric amplitudes in V, Rc, Ic and use them to estimate spot properties, using a grid-based method that is also propagating uncertainties. We verify the method on a partial data set with high cadence and all five broad-band filters. The method yields spot temperatures and fractional spot coverage with typical uncertainties of 100 K and 3 – 4 %, respectively. V1598 Cyg consistently exhibits spots that are a few hundred degrees warmer than the photosphere, most likely indicating that the light curve is dominated by chromospheric plage. The spot activity varies over our observing baseline, with a typical time scale of 0.5 – 1 yr, which we interpret as the typical spot lifetime. Combining our light curve with archival data, we find a six year cycle in the average brightness, that is probably a sign of a magnetic activity cycle.

show abstract

Magnetic topologies of young suns: the weak-line T Tauri stars TWA 6 and TWA 8A

Cited by 33 publications

References 84 publications

Characterizing the X-Ray Emission of Intermediate-mass Pre-main-sequence Stars

Characterizing the X-Ray Emission of Intermediate-mass Pre-main-sequence Stars

ISO-ChaI 52: a weakly accreting young stellar object with a dipper light curve

A survey for variable young stars with small telescopes – III. Warm spots on the active star V1598 Cyg

Contact Info

Product

Resources

About