Object of the Week November 5, 2017 – Pa 5

Object of the Week November 5, 2017 – Pa 5

Pa 5, PN G076.3+14.1, DSH J1919.5+4445, WHI J1919+44

Type: Planetary Nebula
Constellation: Cygnus
RA: 19h 19m 30.5s
DEC: +44° 45’ 44”
Magnitude: 15.7v
Size: 157” x 154”

J19195+4445, KIC 8619526
Type: Central Star
Type: PG1159
Magnitude (central star): 15.84

The planetary nebula Patchick 5 (PA 5) was discovered in 2005 by Dana Patchick, a member of the Deep Sky Hunters (DSH). The DSH group searches for previously unidentified objects in the archives of the Digital Sky Survey. To date the group has over 50 discoveries confirmed.

PA 5 has been classified as a probable bipolar planetary nebula. In direct images (DSS) it looks like a bipolar, but only the northeast lobe is apparent and the opposite lobe is much fainter. Its morphology is dominated by a dense equatorial toroid and faint polar extensions. The O-III and Hα images show a bright bar that looks like an equatorial structure with a faint lobe extending perpendicular to it toward the northeast. A much fainter extension is barely appreciated on the opposite side.

Attachment 2799
Images of PA 5 obtained at the OAN-SPM 84 cm telescope


Attachment 2802
Attachment 2800
Images by Bernard Hubl, 2017

I was unable to locate any visual observations of PA 5; so, with the Cygnus well placed in the northern skies during this time of the year it presents a perfect opportunity for Deep Sky Forum members to give it a go. I anticipate this will be a challenging object.

The central star of PA 5 is itself an interesting object. The discovery paper by D. Patchick also presented a spectrum of the central star and remarked on this star being a very hot PG1159 star. A PG 1159 star, often also called a pre-degenerate, is a star with a hydrogen-deficient atmosphere that is in transition between being the central star of a planetary nebula and being a hot white dwarf. This is a rare O(He) spectral type. However, the story becomes even more interesting. From the spectrum, it was also discovered that the central star has a periodic variability consistent with a companion.

There happen to be six planetary nebulae known in the Kepler space telescope field of view. One of those is PA 5 and its central star Kepler Input Catalog (KIC) 8619526. Kepler’s light curve of the central star of Pa 5 gives a consistent period of 1.12 days with an amplitude of 0.5 mmag. It further shows extremely minimal orbital radial velocity shift. If the companion is a binary star it is being seen close to pole on. But even if that is the case the small amplitude of the curve implies the likely existence of a planetary companion.

Give it a go and let us know!

I'm a bit surprised no one has responded to this OOTW, though Mark certainly picked an obscure planetary. I've made one (negative) observation back in August 2008 with my 18". Of special interest is that Dana and I looked for the planetary together at a local S.F. Bay area site!

18" (8/30/08, Lake Sonoma): I searched for this new planetary along with Dana Patchick, who found this object in 2005 searching the DSS. I was easily able to identify the field using Dana's finder charts that he brought along. The very faint central star (mag 15-15.5) was visible, but there was no sign of the large, low surface brightness planetary. The central star is located 2.2' SE of a 16" pair of mag 12 stars and 4' ESE of a mag 10 star.

By the way, Dana made the first known visual observations of several Abell and other faint planetaries back in 1981 and 1982. He may know whether there have been reported visual observations of Pa 5.

Hi Steve,

what have sky conditions been like when you both tried? Not even the barlike brightening was visible? Cool thing observing with the discoverer btw :-)

CS
Norman

I attempted Pa 5 on 7-23-2014 from latitude 30 North, elevation 1591 meters, using my 30" f/4.5 at various powers from 226x to 769x. The sky conditions were transparency 6/10, seeing 7/10. My notes:
"Not seen. Central star held, but nebula not detected. No response to UHC or O-III."