A Spectroscopic Survey of Subarcsecond Binaries in the Taurus-Auriga Dark Cloud with the Hubble Space Telescope

By P. Hartigan, Scott J. Kenyon. 2002

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We report the results of a spectroscopic survey of 20 close T Tauri binaries in the Taurus-Auriga dark cloud where the separations between primaries and their secondaries are less than the typical size of a circumstellar disk around a young star. Analysis of low- and medium-resolution Space Telescope Imaging Spectrograph spectra yields the stellar luminosities, reddenings, ages, masses, mass accretion rates, IR excesses, and emission-line luminosities for each star in each pair. We examine the ability of IR color excesses, Hα equivalent widths, [O I] emission, and veiling to distinguish between weak emission and classical T Tauri stars. Four pairs have one classical T Tauri star (CTTS) and one weak-lined T Tauri star (WTTS); the CTTS is the primary in three of these systems. This frequency of mixed pairs among the close T Tauri binaries is similar to the frequency of mixed pairs in wider young binaries. Extinctions within pairs are usually similar; however, the secondary is more heavily reddened than the primary in some systems, where it may be viewed through the primary's disk. Mass accretion rates of primaries and secondaries are strongly correlated, and Hα luminosities, IR excesses, and ages also correlate within pairs. Primaries tend to have somewhat larger accretion rates than their secondaries do and are typically slightly older than their secondaries according to three different sets of modern pre-main-sequence evolutionary tracks. Age differences for XZ Tau and FS Tau, systems embedded in reflection nebulae, are striking: the secondary in each pair is less massive but more luminous than the primary. The stellar masses of the UY Aur and GG Tau binaries measured from their rotating molecular disks are about 30% larger than the masses inferred from the spectra and evolutionary tracks. This discrepancy can be resolved in several ways, among them a 10% closer distance for the Taurus-Auriga dark cloud.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/fa05a85c5be5893203a32beae24de3295ab00319

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Citations in the corpus

On the Evolutionary Status of Class I Stars and Herbig-Haro Energy Sources in Taurus-Auriga (2004, methodology): “Based on the calculations of Hartigan et al. (1991), who model the emission from the accretion shock as a slab of pure hydrogen gas of constant temperature and density in LTE, Hartigan & Kenyon (2003) estimate that the bolometric correction for an excess measured over 6000–6500 8 is 35.”
Star and Protoplanetary Disk Properties in Orion's Suburbs (2009, methodology): “…further we gathered a large set of accretion rate estimates from the literature (Gullbring et al. 1998; White & Basri 2003; Muzerolle et al. 2003; Hartigan & Kenyon 2003; Calvet et al. 2004; Muzerolle et al. 2005; Natta et al. 2006; Mohanty et al. 2005; Garcia Lopez et al. 2006; Herczeg &…”
UV Excess Measures of Accretion onto Young Very Low Mass Stars and Brown Dwarfs (2008, methodology): “Using logLacc = −29.67+logF6190 calculated empirically from our Keck I/LRIS spectra (see Tables 4 and 11), we find Lacc that are 0.28 − 0.75 times those calculated by Hartigan & Kenyon (2003).”
Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics (2008, background): “The coevality of stellar binary components at the <1 Myr level is well-motivated observationally (e.g. Hartigan et al. 1994; Hartigan & Kenyon 2003).”
Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping (2008, background): “5 This value, from Elias (1978), is so entrenched in the literature that we will use it despite the plausible suggestion by Hartigan & Kenyon (2003) that the distance should be reduced by about 10%, to 126 pc.”
The Ages of Stars (2007, background): “Hartigan & Kenyon (2003) also looked at binaries in Taurus-Auriga and found that primaries appeared to be systematically older than their secondaries for three different sets of PMS evolutionary tracks and that some pairs were unusually discrepant, perhaps because of underestimated veiling.”
THE MASS DEPENDENCE BETWEEN PROTOPLANETARY DISKS AND THEIR STELLAR HOSTS (2013, background): “…assumed spectral type uncertainty is ±1 subclass. bThe spectral classifications were collated from the following references: 1 = Luhman et al. (2010), 2 = Hartigan & Kenyon (2003), 3 = Hernández et al. (2004), 4 = Furlan et al. (2011), 5 = White & Ghez (2001), 6 = Itoh et al. (2005), 7 =…”
Stellar Multiplicity (2013, unknown): “Nonetheless, in the absence of complete spectroscopic follow-up campaigns (e.g., Hartigan & Kenyon 2003, White & Ghez 2001), this is the only available tool in most cases.”
BANYAN. XI. The BANYAN Σ Multivariate Bayesian Algorithm to Identify Members of Young Associations with 150 pc (2018, unknown): “…Zacharias et al. 2013; (59) Walter et al. 1988; (60) Kraus et al. 2017; (61) Wichmann et al. 2000; (62) Hartigan et al. 1994; (63) Welty et al. 1994; (64) Hartigan & Kenyon 2003; (65) Zacharias et al. 2012; (66) Mart́ın et al. 2005; (67) Herbig 1977; (68) Roeser et al. 2010; (69) Hartmann et al.…”
A Survey and Analysis of Spitzer Infrared Spectrograph Spectra of T Tauri Stars in Taurus (2006, background): “UZ Tau A is surrounded by an accreting circumbinary disk; even though the B components are also surrounded by accretion disks, their outer disks are likely truncated (Jensen et al. 1996; Simon et al. 2000; Hartigan & Kenyon 2003).”