.goutputstream-*?

[Wiky <wiiiky yeah net>]

 Hello,I'm writing a program, which download file from web and save it.
I use GFileOutputStream to save the data.

 httper->fOutput = g_file_replace(file, NULL, FALSE, G_FILE_CREATE_NONE,
                                     NULL, NULL);
...
 g_output_stream_write(G_OUTPUT_STREAM(httper->fOutput),
                          ptr, len, 0, NULL);

And now I find a series of files named .goutputstream-* in the directory.
What are they used for? and how to avoid creating them?

Sorry for my English