def blackbody_temperature(bmag, vmag):
    """
    calculate blackbody temperature using the Ballesteros formula; Eq. 14 in
    https://arxiv.org/pdf/1201.1809.pdf
    """
    t_bb = 4600 * (
        (1 / (0.92 * (bmag - vmag) + 1.7))
        + (1 / (0.92 * (bmag - vmag) + 0.62))
    )
    return t_bb