def calc_radius_from_velrs_times(velr_1, velr_2, time_1, time_2):
    """Calculate the radius of a star from the radial velocities of the stars and    relative times of eclipse events. Assumes inclination = 90 deg, no eccentricity. 
    
    Parameters
    ----------
    velr_1 : float
        Observed radial velocity of star 1. Unit is m/s.
    velr_2 : float
        Observed radial velocity of star 2. Unit is m/s.
    time_1 : float
        Relative time of beginning of ingress (first contact). Unit is seconds.
    time_2 : float
        Relative time of end of ingress or beginning of egress.
        during primary minimum (occultation event). Unit is seconds.
        If eclipse is not total, relative time of end of ingress == relative time of beginning of egress.
        For radius of smaller-sized star: time_2 = relative time of end of ingress.
        For radius of greater-sized star: time_2 = relative time of beginning of egress.
    
    Returns
    -------
    radius : float
        Radius of star. Unit is meters.
        For radius of smaller-sized star: time_2 = relative time of end of ingress.
        For radius of greater-sized star: time_2 = relative time of beginning of egress.
        
    See Also
    --------
    calc_radii_ratio_from_light, calc_radius_sep_g_from_sep, calc_radius_sep_s_from_sep
        
    Notes
    -----
    Note: Calculated radius may not agree with radii from methods that do not  
    rs = (vr1 + vr2)/2 * (t2 - t1), t2 is end of ingress
    rg = (vr1 + vr2)/2 * (t2 - t1), t2 is beginning of egress
    From equations 7.8, 7.9 in section 7.3 of [1]_.
    
    References
    ----------
    .. [1] Carroll and Ostlie, 2007, An Introduction to Modern Astrophysics
    
    """
    radius = (velr_1 + velr_2) / 2.0 * (time_2 - time_1)
    return radius
