def color_Teff_relations(V, Ks):
    """
	Estimates stellar effective temperature based on photometry.
	Args:
		V (float): V magnitude of star
		Ks (float): Ks magnitude of star.
	Returns:
		Teff (float): Star effective temperature [K].
	"""
    if V - Ks < 5.05:
        theta = 0.54042 + 0.23676 * (V - Ks) - 0.00796 * (V - Ks) ** 2
        Teff = 5040 / theta
    elif V - Ks > 5.05:
        theta = -0.4809 + 0.8009 * (V - Ks) - 0.1039 * (V - Ks
            ) ** 2 + 0.0056 * (V - Ks) ** 3
        Teff = 5040 / theta + 205.26
    return Teff
