Jonckheere 900 (J900) is a bipolar planetary nebula discovered in 1912 by French astronomer R. Jonckheere using the Lille University observatory, he initially thought it was a double star, the Hubble Space Telescope later determined the object was not a double star. J900 has a distance ranging from 3.89 to 6 kiloparsecs (kpc) with an average value of ~4.6 kpc, which shows that the ionization front is located at ~8.5 arcseconds away from the central star. The nebula has a temperature floor of ~829 K, which is from a H2 temperature of 755±36 K. The J900 nebula was detected to have Kr III and Se IV lines. Forbidden Lines of [Kr], [Rb], and [Xe] were detected in the BOES spectrum while the F line was detected using the mid-IR Spitzer infrared spectrograph. The nebula features H2 lines emitted from both a ~670 K warm and a ~3200 K hot region. Emission lines with calculated Te and ne include: the [O III] line with Te = 11,600±1160 K and ne = 3600±1160 cm-3, the [S III] line with Te = 13,000 K, the [N II] line with Te = 11,500 K, the [O II] line with Te = 10,300 K and ne = 3980 cm-3, the [S II] line with Te = 7800 K and ne = 3600 cm-3, and the [Ar IV] line with ne = 8240 cm-3. A unnamed faint field star located roughly 11 arcseconds away from the central star is located next to J900, giving the illusion of a double system.
Central star The star has an effective temperature of ~134,800 K calculated using the observed I(He II 4686 Å)/I(H β) ratio. The star evolved from an initial mass of ~2.0 M⊙. The central star has a visual magnitude of 17.8 mag.
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