Mz 1 (Menzel 1), is a bipolar planetary nebula (PN) in the constellation Norma.
Menzel 1 is a bright planetary nebula that has a prominent central ring of enhanced emission. One model of its structure is a three-dimensional hour-glass shape with a smoothly decreasing density starting from the waist or equator as measured outwardly to the poles. It is radially expanding at a rate of about 23 km/s and estimated to be around 4,500 to 10,000 years old and has its polar axis oriented at an angle of around 40ð from the plane of the sky. Its central star is estimated to have a mass of . In 1992 Schwarz, Corradi, & Melnick published narrow band images of Mz 1 in Hñ and [OIII]. H<sub>2</sub> emission was observed in Mz 1 by Webster, Payne, Storey, Dopita (1988). However, despite its relative brightness, Mz 1 has only been studied in a few papers .
Mz 1 was discovered by Donald Howard Menzel in 1922.
<ol type="a"> <li>3,400 ñ 500 ly distance àsin( 76 diameter_angle / 2 ) = 0.63 ñ 0.09 ly. radius</li> <li>12.0 apparent magnitude - 5 * (log<sub>10</sub>(1,050 ñ 150 pc distance) - 1) = 1.9 ñ 0.3 absolute magnitude</li> </ol>