def tdust_devicente(luminosity, radio, gradient, td):
    """
    Returns Tdust given luminosity in Lsun and radio in cm
    Eq.1 From de Vicente et al 2000
    """
    if gradient == True:
        Tdust = 15.222 *(luminosity * (1e16/radio)**2.)**(1/4.)  
    else:
        Tdust = td
    return Tdust