Create query for both custom post type and category

The arguments for your query would be like:

$args = array(
    'post_type' => 'articles',               
    'tax_query' => array(
        array(
            'taxonomy' => 'category',
            'field'    => 'name',
            'terms'    => 'news',                                    
        ),
    ), 
);

$loop = new WP_Query( $args );

if ( $loop->have_posts() ) :
    while ( $loop->have_posts() ) : $loop->the_post();  
    endwhile;
endif;