An observational approach to the early stages of stellar evolution

Ambartsumian, V. A.; Mirzoyan, L. V.

doi:10.1007/bf00651314

Cited by 20 publications

(11 citation statements)

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“…T Tau N is one of the most luminous and massive of the T Tauri class of young stars in the Taurus-Auriga star forming region. It was identified as the prototypical young star in part because of its historical variability (Ambartsumian 1947;Lozinskii 1949;, but in the last decade it has not varied in optical flux at a significant level (Ismaliov 1997). We find that it also does not vary in broadband near infrared flux, but that variations in the Brackett line emission suggest fluctuations in its mass accretion rate.…”

Section: T Tau N: the Prototypical Young Starmentioning

confidence: 99%

“…Joy (1945) used T Tau as the prototype of a new class of stars that show significant variability, are associated with bright or dark nebulosities and have characteristic emission line spectra. Ambartsumian (1947; first proposed that the T Tauris are in fact young solar type stars in an early stage of formation. T Tau is a ∼1 Myr old K0 star with a mass of ∼2 M ⊙ and a visual extinction of ∼1.5 magnitudes (Cohen & Kuhi 1979;.…”

Section: Introductionmentioning

confidence: 99%

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A High Spatial Resolution Infrared View of the T Tauri Multiple System

Beck

Schaefer

Simon

et al. 2004

ApJ

130

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We present the results of our monitoring study of the IR photometric and spectroscopic variability of the T Tau multiple system. We also present data on the apparent position of T Tau S with respect to T Tau N, and two new spatially resolved observations of the T Tau Sa-Sb binary. T Tau N has not varied by more than 0.2 magnitudes in K and L' flux during the 8 years of our observations, though its Br gamma and Br alpha emission line fluxes have varied by nearly a factor of four during this time. For the unresolved T Tau S system, we have derived a 20 year light curve based on our images and on measurements available in the literature. T Tau S varies by 2-3 magnitudes in K and L'-band brightness in a ``redder when faint'' manner, consistent with changes along the line of sight in the amount of material that follows an ISM extinction law. Absorption in the 3.05um water-ice feature is seen only in the spectra of T Tau S and it displays variations in depth and profile. H_2 (2.12 um) emission is also detected only at the position of T Tau S; the H_2, Br gamma and Br alpha emission line fluxes also vary. We have found that the apparent positions of T Tau S with respect to T Tau N and T Tau Sb with respect to Sa are consistent with gravitationally bound orbital motion. The possible orbits of the T Tau S binary imply that Sa is likely the most massive component in this young triple. A reanalysis of the motion of the radio source associated with T Tau S provides no evidence for an ejection event in the T Tau system.Comment: 49 pages, including 17 figures. Accepted for publication in the Astrophysical Journa

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Section: T Tau N: the Prototypical Young Starmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A High Spatial Resolution Infrared View of the T Tauri Multiple System

Beck

Schaefer

Simon

et al. 2004

ApJ

130

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“…CMa OB1 was first recognised as a stellar association by Ambartsumian (1947), and more members were identified by Claría (1974b,a). Within the boundaries of CMa OB1, van den Bergh (1966) found a number of stars associated with reflection Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.ustrasbg.fr/cgi-bin/qcat?J/A+A/ nebulae, a grouping that he called CMa R1.…”

Section: Introductionmentioning

confidence: 99%

Hα emission-line stars in molecular clouds

Pettersson

Reipurth

2019

A&A

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A deep objective-prism survey for Hα emission stars towards the Canis Major star-forming clouds was performed. A total of 398 Hα emitters were detected, 353 of which are new detections. There is a strong concentration of these Hα emitters towards the molecular clouds surrounding the CMa OB1 association, and it is likely that these stars are young stellar objects recently born in the clouds. An additional population of Hα emitters is scattered all across the region, and probably includes unrelated foreground dMe stars and background Be stars. About 90% of the Hα emitters are detected by WISE, of which 75 % was detected with usable photometry. When plotted in a WISE colour-colour diagram it appears that the majority are Class II YSOs. Coordinates and finding charts are provided for all the new stars, and coordinates for all the detections. We searched the Gaia-DR2 catalogue and from 334 Hα emission stars with useful parallaxes, we selected a subset of 98 stars that have parallax errors of less than 20% and nominal distances in the interval 1050 to 1350 pc that surrounds a strong peak at 1185 pc in the distance distribution. Similarly, Gaia distances were obtained for 51 OB-stars located towards Canis Major and selected with the same parallax errors as the Hα stars. We find a median distance for the OB stars of 1182 pc, in excellent correspondence with the distance from the Hα stars. Two known runaway stars are confirmed as members of the association. Finally, two new Herbig-Haro objects are identified.

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“…What was less evident in the late 1940s and early 1950s was the evolutionary status of TTSs. Although Ambartsumian (1947Ambartsumian ( , 1954 introduced the concept of stellar OB and T associations and proposed that they were the sites of ongoing star formation shortly after TTSs were discovered, these ideas were long in gaining mainstream acceptance in the community, presumably due to the difficulties of communication between the Eastern the Western worlds after World War II. The first paradigm shift, from stars passing by chance through interstellar clouds to stars being born in interstellar clouds, took place around 1955 and was strongly influenced by Ambartsumian's ideas.…”

Section: S and 1950s: First Tts Modelsmentioning

confidence: 99%

The accretion disk paradigm for young stars

Bertout

2007

Proc. IAU

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Abstract. Accretion and magnetic fields play major roles in several of the many models put forward to explain the properties of T Tauri stars since their discovery by Alfred Joy in the 1940s. Early investigators already recognized in the 1950s that a source of energy external to the star was needed to account for the emission properties of these stars in the optical range.The opening of new spectral windows from the infrared to the ultraviolet in the 1970s and 1980s showed that the excess emission of T Tauri stars and related objects extends into all wavelength domains, while evidence of outflow and/or infall in their circumstellar medium was accumulating.Although the disk hypothesis had been put forward by Merle Walker as early as 1972 to explain properties of YY Orionis stars and although Lynden-Bell and Pringle worked out the accretion disk model and applied it specifically to T Tauri stars in 1974, the prevailing model for young stellar objects until the mid-1980s assumed that they experienced extreme solar-type activity. It then took until the late 1980s before the indirect evidence of disks presented by several teams of researchers became so compelling that a paradigm shift occurred, leading to the current consensual picture.I briefly review the various models proposed for explaining the properties of young stellar objects, from their discovery to the direct observations of circumstellar disks that have so elegantly confirmed the nature of young stars. I will go on to discuss more modern issues concerning their accretion disk properties and conclude with some results obtained in a recent attempt to better understand the evolution of Taurus-Auriga young stellar objects.

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An observational approach to the early stages of stellar evolution

Cited by 20 publications

References 20 publications

A High Spatial Resolution Infrared View of the T Tauri Multiple System

A High Spatial Resolution Infrared View of the T Tauri Multiple System

Hα emission-line stars in molecular clouds

The accretion disk paradigm for young stars

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