Which of the following statements is true of T Tauri stars?
A) They are often surrounded by thick disks of gas and dust.
B) They have completely inactive chromospheres.
C) They have very weak magnetic dynamos.
D) They are post-main-sequence stars.
A
You might also like to view...
An electron with a charge value of 1.6 × 10^?19 C is moving in the presence of an electric field of 400 N/C. What force does the electron experience?
a. 8.0E–21 N b. 6.4E–22 N c. 6.4E–17 N d. 4.0E+17 N e. 1.6E–17 N
The mass of the Milky Way Galaxy can be estimated by:
A) the orbital motions of the stars within the galaxy. B) the mass of the planets in the Solar System. C) the luminosity of the stars of the neighboring galaxies. D) the concept laid down by the spiral density wave theory.
What is different about locating images in convex mirrors compared to locating images in concave mirrors?
a. Among many differences, ray diagrams do not work for convex mirrors. b. Convex mirrors require more rays for a minimum ray diagram. c. Everything is the same except that the focal point is located behind the mirror. d. Because convex mirrors have no focal point, rays must be constructed differently. e. Because convex mirrors have no optic axis, rays must be constructed differently.
Our molten core is believed to consist primarily of the element ________
Fill in the blank(s) with correct word