We selected blue horizontal branch ( BHB ) stars within the expected distance range and sky position of the Hermus Stream from Data Release 10 of the Sloan Digital Sky Survey .
We identify a moving group of 19 BHB stars that are concentrated within two degrees of the Hermus Stream , between 10 and 14 kpc from the Sun .
The concentration in velocity is inconsistent with a Gaussian distribution with 98 % confidence ( 2.33 sigma ) .
The stars in the moving group have line-of-sight velocities of v _ { gsr } \sim 50 km s ^ { -1 } , a velocity dispersion of \sigma _ { v } \lesssim 11 km s ^ { -1 } , a line-of-sight depth of \sim 1 kpc , and a metallicity of [ Fe/H ] = -2.1 \pm 0.4 .
The best-fit orbit has a perigalacticon of \sim 4 kpc , apogalacticon of \sim 17 kpc , orbital period of \sim 247 Myr , eccentricity e = 0.62 , and inclination i \sim 75 ^ { \circ } from b = 90 ^ { \circ } .
The BHB stars in the stream are estimated to be 12 Gyr old .
An N -body simulation of a mass-follows-light ultrafaint dwarf galaxy with mass 10 ^ { 6 } M _ { \odot } and radius 40 pc is consistent with the observed properties .
The properties of the identified moving group of 19 BHB stars are close enough to those of the Hermus Stream ( which is traced predominantly in turnoff stars ) that we find it likely that they are associated .
If that is the case , then our orbit fit would imply that there is no relationship between the Hermus and Phoenix streams , as previously proposed .