Celestia Forums

The following from the rotation periods in the Celestia source codes. On the first lines representing the "V" rotation periods, I notice a cliff between F9 and G0 (0.7 and 11.1). It occurs to me that if the FVs are in units of solar rotational periods and the GVs are by days, there isn't as obvious a cliff (0.7 x 25.4 = 17.78). Is this 1) a unit difference between calculations in G or less versus F or higher classes, 2) an error in data conversion, or 3) F+ stars just suddenly rotate bloody fast?

static float rotperiod_F[3][10] =
{
{ 0.7f, 0.7f, 0.6f, 0.6f, 0.5f, 0.5f, 0.5f, 0.6f, 0.6f, 0.7f },
{ 1.9f, 2.5f, 3.0f, 3.5f, 4.0f, 4.6f, 5.6f, 6.7f, 7.8f, 8.9f },
{ 135.0f, 141.0f, 148.0f, 155.0f, 162.0f, 169.0f, 175.0f, 182.0f, 188.0f, 195.0f },
};

static float rotperiod_G[3][10] =
{
{ 11.1f, 18.2f, 25.4f, 24.7f, 24.0f, 23.3f, 23.0f, 22.7f, 22.3f, 21.9f },
{ 10.0f, 13.0f, 16.0f, 19.0f, 22.0f, 25.0f, 28.0f, 31.0f, 33.0f, 35.0f },
{ 202.0f, 222.0f, 242.0f, 262.0f, 282.0f,
303.0f, 323.0f, 343.0f, 364.0f, 384.0f },
};

The rotation periods of stars in the source code are given in days from what I can tell. And yes, type F stars appear to rotate fast, at least according to who ever contributed the data to Celestia.

F-type stars do indeed have more rapid rotation than G-type stars.

Here's a paper that may be of some help:

http://www.google.com/url?sa=t&rct=j&q=f-typ%20stars%20rotation&source=web&cd=2&ved=0CDoQFjAB&url=http%3A%2F%2Fassets.cambridge.org%2F97805217%2F72181%2Fsample%2F9780521772181ws.pdf&ei=RYudUJWjOYiu8AS_-IDQCA&usg=AFQjCNGbbFr_vBUemQyL0wqiDdBN609mMA&cad=rja

Check out Table 1.1 for an interesting and brief "snapshot" of type vs. rotation speeds.

The paper also goes into the fact that singular stars generally rotate faster than early-type components of close binaries.

Enjoy.