The Protostar and T-Tauri Stage of Evolution
- Properties of Protostars
- Size and Mass
- Changes
- Lifetime
- Constitution and Evolution
- Properties of T-Tauri Stars
- Classical T-Tauri (Infrared)
- Weak Line T-Tauri
- Accretion Disk
- Jets
- Models
- The numbers on the HR Diagram correspond to the
stages of the star as listed in the table below. The HR Diagram
plots the progression of the star's energy output versus its
surface temperature.
At stages 1, 2, and 3 the cloud is very cool (off the right of the
diagram) and very bright (off the top of the diagram).
| STAGE |
APPROX.
TIME TO
NEXT STAGE
(Million yrs) |
CENTRAL TEMPER
-ATURE
(K) |
SURFACE TEMPER
-ATURE (K) |
CENTRAL DENSITY (particles/cm3) |
DIAMETER* |
OBJECT |
| 1 |
2 My |
10 |
10 |
1000 |
100 ly |
Interstellar cloud |
| 2 |
0.03 My |
100 |
10 |
106 |
0.1 ly |
Cloud fragment |
| 3 |
0.1 My |
10,000 |
100 |
1012 |
70 AU |
Cloud fragment/protostar |
| 4 |
1 My |
1,000,000 |
3000 |
1018 |
0.7 AU |
Protostar |
| 5 |
10 My |
5,000,000 |
4000 |
1022
sg = 0.015 |
7 RSun |
Protostar |
| 6 |
30 My |
10,000,000 |
4500 |
1025
sg = 15 |
1.4 RSun |
Star |
| 7 |
10,000 My |
15,000,000 |
6000 |
1026
sg = 150 |
1 RSun |
Main-sequence star |
* Units of Length
- 1 ly = 1 light year = 1013 km
Distance to the nearest star = 4.3 ly
- 1 AU = 1 Astronomical Unit = 1.5x108 km
Solar System diameter = 80 AU
- 1 RSun = Radius of the Sun = 1.4x106 km