T-Tauri Stars

June 13, 2016
T-Tauri Stars
Young stars and nebulosity in Chamaeleon, a constellation visible predominantly in the southern sky. A new study of young (T-Tauri) stars in this region has determined their ages as being between about five - six million years old, as well as determining other properties. Credit: FORS Team, 8.2-meter VLT Antu, ESO

A newborn star typically goes through four stages of adolescence. It begins life as a protostar still enshrouded in its natal molecular cloud, accreting new material and developing a proto-planetary disc. Slowly, stellar winds and radiation blow away the surrounding shell of gas and dust, and the third stage, when the surrounding envelope has cleared, is called the T-Tauri phase. T-Tauri stars (the class is named after the first star of this type that was so identified) are less than about ten million years old, and provide astronomers with promising candidates in which to study the early lives of stars and planets. They were among the first young stars to be identified because the earlier stages, still embedded in their birth clouds, were blocked from optical observations by the dust. In the fourth stage, the disk stops accreting and the source's radiation comes from the star's photosphere. T-Tauri stars produce strong X-rays, primarily by what is thought to be coronal activity much like the coronal activity in our own Sun, although in some cases a component might be coming from hot material in the dusty disk.

Measurements of T-Tauri circumstellar disks provide important tests for theories of planet formation and migration. Near-infrared results, for example, sample the hotter temperature dust grains, and can reveal the presence of gaps in the disk (perhaps cleared by massive planets) when an expected ring of warm dust around the star is not detected. Astronomers during the past few decades have been able to use infrared space telescopes like Spitzer to probe T-Tauri disks, but there are still many puzzles, in particular about the mechanisms responsible for the accretion, the subsequent dissipation of material, and the evolutionary ages when these processes occur.

CfA astronomer Philip Cargile was a member of a team of seven scientists studying the evolution of these stars and their disks. They took detailed optical observations (including spectra) of a sample of twenty-five X-ray selected T-Tauri stars in two nearby star-forming clouds to derive their ages and stellar masses. They find that most of the sources in one cloud are between about five and six million year old; a couple turn out to be more like twenty-five million years old and can now be excluded from the T-Tauri class. In the other cloud, most of the sources are younger than about ten million years. The results agree well with theoretical models and other observations. Perhaps more usefully, the results help to identify true T-Tauri with disks that would be suitable for imaging observations with a new generation of large telescopes.

Explore further: Infant solar system shows signs of windy weather

More information: "Fundamental Stellar Parameters for Selected T-Tauri Stars in the Chamaeleon and Rho Ophiuchus Star-Forming Regions," D.J. James, A.N. Aarnio, A.J.W. Richert, P.A. Cargile, N.C. Santos, C.H.F. Melo, and J. Bouvier, MNRAS 459, 1363. arxiv.org/abs/1603.00820

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FredJose
1.3 / 5 (15) Jun 13, 2016
A newborn star typically goes through four stages of adolescence. It begins life as a protostar still enshrouded in its natal molecular cloud, accreting new material and developing a proto-planetary disc. Slowly, stellar winds and radiation blow away the surrounding shell of gas and dust, and the third stage, when the surrounding envelope has cleared, is called the T-Tauri phase.

Really? has this actually been observed as being a recorded FACT? or is this simply the currently prevailing dogma, i.e. most acceptable story telling because the idea that someone actually created these things is supernatural? So scientists are quite open to accepting other supernatural causes, as long as it's not by some intelligent, live being that actually owns everything. Until that day arrives when the actual formation and self-birth of a star has been observed and recorded for posterity, one should take these stories with a spade of salt since that is all that they are.
antialias_physorg
4.7 / 5 (14) Jun 13, 2016
ecause the idea that someone actually created these things is supernatural

Has your god been observed? No.
So by your own 'logic' you're peddling horeshit.
shavera
5 / 5 (10) Jun 13, 2016
So scientists are quite open to accepting other supernatural causes

lol, wut?

Imagine I give you an album of pictures of people. You leaf through them. You see some children, some babies, some seniors, some middle aged. It's not a huge stretch of imagination to hypothesize that humans grow from babies into children into adults into seniors.

Imagine I give you some facts: The universe has gasses in it between where stars are. That gas doesn't have a uniform distribution. Gravity attracts gas from where it's less dense to where it's more dense. When gas gets denser, it heats up. When certain gasses, particularly those common in our universe, heat up while they're very dense, they may undergo fusion to release even more heat and energy. That heat and energy pushes outward at the same time gravity pulls inward.

Which one of those facts are wrong, and why, exactly is it wrong?
Guy_Underbridge
4.3 / 5 (11) Jun 13, 2016
Really? has this actually been observed as being a recorded FACT?
I'll believe they were created by a 'live being that actually owns everything' when I personally see them being created by a 'live being that actually owns everything'.

I'm glad we agree, Fred
Tektrix
5 / 5 (6) Jun 13, 2016
@FJ- Your faith is far more flawed than our science.

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