B- And a-Type Stars in the Taurus-Auriga Star-Forming Region

Mooley, K. P.; Hillenbrand, Lynne A.; Rebull, L. M.; Padgett, Deborah; Knapp, G. R.

doi:10.1088/0004-637x/771/2/110

Cited by 35 publications

(25 citation statements)

References 75 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To investigate its origin, we have inspected the SPIRE images of B7/L1495 at different wavelengths. These images show that B7/L1495-south lies inside a region of bright and extended farinfrared emission in the vicinity of V892 Tau, a Herbig Ae/Be star first identified by Elias (1978) and with a total luminosity of ≈400 L (Sandell et al 2011;Mooley et al 2013) that lies about 300 (0.2 pc) in projection from B7/L1495-south. A grey body analysis of the SPIRE emission, indicates that the dust temperature in the region is elevated, and that it gradually increases toward V892 Tau, where it reaches about 15 K, or 50% higher than in B7/L1495-north.…”

Section: Comparison With Spire Data and N 2 H + Abundancementioning

confidence: 77%

Chains of dense cores in the Taurus L1495/B213 complex

Tafalla

Hacar

2015

A&A

151

174

View full text Add to dashboard Cite

Context. Cloud fragmentation into dense cores is a critical step in the process of star formation. A number of recent observations show that it is connected to the filamentary structure of the gas, but the processes responsible for core formation remain mysterious. Aims. We studied the kinematics and spatial distribution of the dense gas in the L1495/B213 filamentary region of the Taurus molecular cloud with the goal of understanding the mechanism of core formation. Methods. We mapped the densest regions of L1495/B213 in N 2 H + (1-0) and C 18 O(2-1) with the IRAM 30 m telescope, and complemented these data with archival dust-continuum observations from the Herschel Space Observatory. Results. The dense cores in L1495/B213 are significantly clustered in linear chain-like groups about 0.5 pc long. The internal motions in these chains are mostly subsonic and the velocity is continuous, indicating that turbulence dissipation in the cloud has occurred at the scale of the chains and not at the smaller scale of the individual cores. The chains also present an approximately constant abundance of N 2 H + and radial intensity profiles that can be modeled with a density law that follows a softened power law. A simple analysis of the spacing between the cores using an isothermal cylinder model indicates that the cores have likely formed by gravitational fragmentation of velocity-coherent filaments. Conclusions. Combining our analysis of the cores with our previous study of the large-scale C 18 O emission from the cloud, we propose a two-step scenario of core formation in L1495/B213. In this scenario, named "fray and fragment", L1495/B213 originated from the supersonic collision of two flows. The collision produced a network of intertwined subsonic filaments or fibers (fray step). Some of these fibers accumulated enough mass to become gravitationally unstable and fragment into chains of closely-spaced cores.

show abstract

Section: Comparison With Spire Data and N 2 H + Abundancementioning

confidence: 77%

Chains of dense cores in the Taurus L1495/B213 complex

Tafalla

Hacar

2015

A&A

151

174

View full text Add to dashboard Cite

show abstract

“…One of them, HD 27778 (62 Tau), is in the direction of the Taurus star-forming region at a projected separation of ∼1°.5 from DF Tau and ∼1°.9 from DG Tau and FZ Tau. At a distance of 225 pc, as measured by Hipparcos (ESA 1997), HD 27778 is not a Taurus member but likely belongs to the older Cas-Tau OB association located behind the Taurus molecular cloud (e.g., Mooley et al 2013). The K I profile obtained by Welty & Hobbs (2001) shows two deep and spectrally resolved absorptions at ∼14.8 km s −1 (consistent with the DF Tau and DG Tau Na I and K I velocities) and ∼18.5 km s −1 (slightly lower than the FZ Tau velocities).…”

Section: Origin Of the Narrow Absorption In The Na I And K I Profilesmentioning

confidence: 91%

NARROW Na AND K ABSORPTION LINES TOWARD T TAURI STARS: TRACING THE ATOMIC ENVELOPE OF MOLECULAR CLOUDS

Pascucci

Edwards

Rigliaco

et al. 2015

ApJ

View full text Add to dashboard Cite

We present a detailed analysis of narrow Na I and K I absorption resonance lines toward nearly 40 T Tauri stars in Taurus with the goal of clarifying their origin. The Na I λ5889.95 line is detected toward all but one source, while the weaker K I λ7698.96 line is detected in about two-thirds of the sample. The similarity in their peak centroids and the significant positive correlation between their equivalent widths demonstrate that these transitions trace the same atomic gas. The absorption lines are present toward both disk and diskless young stellar objects, which excludes cold gas within the circumstellar disk as the absorbing material. A comparison of Na I and CO detections and peak centroids demonstrates that the atomic gasand molecular gas are not co-located, the atomic gas being more extended than the molecular gas. The width of the atomic lines corroborates this finding and points to atomic gas about an order of magnitude warmer than the molecular gas. The distribution of Na I radial velocities shows a clear spatial gradient along the length of the Taurus molecular cloud filaments. This suggests that absorption is associated with the Taurus molecular cloud. Assuming that the gradient is due to cloud rotation, the rotation of the atomic gas is consistent with differential galactic rotation, whereas the rotation of the molecular gas, although with the same rotation axis, is retrograde. Our analysis shows that narrow Na I and K I absorption resonance lines are useful tracers of the atomic envelope of molecular clouds. In line with recent findings from giant molecular clouds, our results demonstrate that the velocity fields of the atomic and molecular gas are misaligned. The angular momentum of a molecular cloud is not simply inherited from the rotating Galactic disk from which it formed but may be redistributed by cloud-cloud interactions.

show abstract

“…It would be premature to conclude that the true Taurus IMF is different until a comprehensive study of F-K stars has been conducted. Furthermore, Mooley et al (2013) have identified a number of B-A stars in Taurus that might significantly modify the inferred IMF, although their membership has been disputed (e.g., Esplin et al 2014), and Herczeg & Hillenbrand (2014) have found that some Taurus members were significantly misclassified when originally observed in the 1960s and 1970s. We therefore suggest that the shape of the Taurus IMF is not yet settled.…”

Section: Implications For the Initial Mass Functionmentioning

confidence: 99%

The Greater Taurus–Auriga Ecosystem. I. There is a Distributed Older Population

Kraus

Herczeg

Rizzuto

et al. 2017

ApJ

158

View full text Add to dashboard Cite

The census of Taurus-Auriga has been assembled over seven decades and inherited the biases and incompleteness of the input studies. The unusual shape of its inferred initial mass function (IMF) and the existence of isolated diskbearing stars suggest that additional (likely disk-free) members remain to be discovered. We therefore have begun a global reassessment of the census of Taurus-Auriga that exploits new data and better definitions of youth and kinematic membership. As a first step, we reconsider the membership of all disk-free candidate members from the literature with spectral type F0, a < < 3 50 5 40 h m h m , and d  < <  14 34 . We combine data from the literature with Keck/HIRES and UH88/SNIFS spectra to test the membership of these candidates using the positions in the Hertzsprung-Russel diagram, proper motions, radial velocities, Hα, lithium, and surface gravity. We find 218 confirmed or likely Taurus members, 160 confirmed or likely interlopers, and only 18 that lack sufficient evidence to draw firm conclusions. A significant fraction of these stars (81/218 = 37%) are not included in the most recent canonical member lists. There are few additional members to the immediate vicinity of the molecular clouds, preserving the IMFs that have been deemed anomalous in past work. Many of the likely Taurus members are instead distributed broadly across the search area. When combined with the known disk hosts, our updated census reveals two regimes: a high-density population with a high disk fraction (indicative of youth) that broadly traces the molecular clouds, and a low-density population with low disk fraction (hence likely older) that most likely represents previous generations of star formation.

show abstract

B- And a-Type Stars in the Taurus-Auriga Star-Forming Region

Cited by 35 publications

References 75 publications

Chains of dense cores in the Taurus L1495/B213 complex

Chains of dense cores in the Taurus L1495/B213 complex

NARROW Na AND K ABSORPTION LINES TOWARD T TAURI STARS: TRACING THE ATOMIC ENVELOPE OF MOLECULAR CLOUDS

The Greater Taurus–Auriga Ecosystem. I. There is a Distributed Older Population

Contact Info

Product

Resources

About