Howard B
October 27th, 2020, 04:48 AM
Emission nebula
Cepheus
RA: 20 45 58
DEC: +67 58 30
Magnitude: variable
Size: variable
I had terrible luck finding an object for this week’s OOTW – it took fourteen searches until I found an object that hasn’t been an OOTW in the past*. The search was worth it though, but tracking down this fascinating variable nebula in Cepheus is even more rewarding.
Gyulbudaghian’s Nebula is a variable object, and I’ve seen it as both a bright and obvious wedge of nebulosity, as well as not seeing any trace of it - and this unpredictability is a big part of why I find this object so fascinating.
Discovered in 1977 by astronomer Armen Gyulbudaghian, this reflection nebula is produced by an energetic outflow from the newly forming star, PV Cephei. We see the northern outflow - the opposing southern outflow is hidden by dust – which makes GM 1-29 much the same type of object as much the brighter Hubble’s Variable Nebula (NGC 2261). This HST image shows a remarkable similarity to 2261.
4052
Assuming GM 1-29 has properties similar to Hubble’s Variable Nebula, the apparent changes in the nebula are caused by shadows produced close to the newly forming star - PV Cephei in this case - by the rapidly changing conditions near its circling dust ring, while the actual nebulosity stays much the same. Because the nebula is an energetic outflow it’s definitely changing shape, but not quickly enough to produce the changes we see. The rapidly changing shadows projected onto the nebula are what produce the variations.
Here are two observations with my 28-inch scope showing the nebula as completely unseen, with only PV Cephei being visible, and five years later as an easily seen fan of light:
“No trace of the nebula – not the slightest hint. I’ve given the area a good workout using 273x and 408x, where I could see PV Cephei, the illuminating star. Fascinating that there’s no nebula to see now, and I even tried all my nebula filters. 21.95 SQM” (September 2008)
4053 4054
“After extensive use of averted vision at 408x and 695x I got a couple of pops of PV Cephei at the vertex of GM 1-29’s fan shaped nebulosity. I also glimpsed it as a faint knot so I’m sure I’m seeing what the atmosphere allows right now. 21.52 SQM” (October 2013)
4055 4056
2013 was the last time I’ve observed GM 1-29, so I don’t know whether it’s visible or not right now. There’s only one way to find out, so…
Give it go and let us know!
*By the way, I did find GM 1-29 was discussed in an Off the Beaten Path forum posting in 2013, but after seven years I’m happy to present it as an OOTW because it’s a variable object. And I really didn't want to keep searching...
Cepheus
RA: 20 45 58
DEC: +67 58 30
Magnitude: variable
Size: variable
I had terrible luck finding an object for this week’s OOTW – it took fourteen searches until I found an object that hasn’t been an OOTW in the past*. The search was worth it though, but tracking down this fascinating variable nebula in Cepheus is even more rewarding.
Gyulbudaghian’s Nebula is a variable object, and I’ve seen it as both a bright and obvious wedge of nebulosity, as well as not seeing any trace of it - and this unpredictability is a big part of why I find this object so fascinating.
Discovered in 1977 by astronomer Armen Gyulbudaghian, this reflection nebula is produced by an energetic outflow from the newly forming star, PV Cephei. We see the northern outflow - the opposing southern outflow is hidden by dust – which makes GM 1-29 much the same type of object as much the brighter Hubble’s Variable Nebula (NGC 2261). This HST image shows a remarkable similarity to 2261.
4052
Assuming GM 1-29 has properties similar to Hubble’s Variable Nebula, the apparent changes in the nebula are caused by shadows produced close to the newly forming star - PV Cephei in this case - by the rapidly changing conditions near its circling dust ring, while the actual nebulosity stays much the same. Because the nebula is an energetic outflow it’s definitely changing shape, but not quickly enough to produce the changes we see. The rapidly changing shadows projected onto the nebula are what produce the variations.
Here are two observations with my 28-inch scope showing the nebula as completely unseen, with only PV Cephei being visible, and five years later as an easily seen fan of light:
“No trace of the nebula – not the slightest hint. I’ve given the area a good workout using 273x and 408x, where I could see PV Cephei, the illuminating star. Fascinating that there’s no nebula to see now, and I even tried all my nebula filters. 21.95 SQM” (September 2008)
4053 4054
“After extensive use of averted vision at 408x and 695x I got a couple of pops of PV Cephei at the vertex of GM 1-29’s fan shaped nebulosity. I also glimpsed it as a faint knot so I’m sure I’m seeing what the atmosphere allows right now. 21.52 SQM” (October 2013)
4055 4056
2013 was the last time I’ve observed GM 1-29, so I don’t know whether it’s visible or not right now. There’s only one way to find out, so…
Give it go and let us know!
*By the way, I did find GM 1-29 was discussed in an Off the Beaten Path forum posting in 2013, but after seven years I’m happy to present it as an OOTW because it’s a variable object. And I really didn't want to keep searching...