I opened the Millennium Star Atlas to page 227, and set the good book
on the shelf of my painter's ladder at Lake Sonoma last night 2/22/03.
I had a particular project on this page so the page itself became my
observing list for the night. That particular project will be a report
in itself. I liked having only one reference to work from. Each MSA
page covers an area 5.4 by 7.4 degrees. On a map of the world, France
would fit in this space. :-)
First the sun set, then after astronomical twilight, the zodiacal light
leaped into view. This wide triangular cone of glow requires a dark site
with good transparency to spot. You may have seen it and thought you
were seeing twilight since they both occur in the same area of the sky.
My first target was also home base for most of my starhops on page 227
of MSA. The Rosette Nebula, NGC2244, 2237-2239 - a showpiece object in
both my 80mm Short Tube 80 finder with a OIII filter in the 25mm
eyepiece, as well as in the 31 Nagler with OIII, and even naked eye,
holding the filter to my eye. Only a portion of the whole nebula was
visible in the 65x view through the 31 mm Nagler. Most everyone who was
interested came over for a look. I spent an hour looking at the detail
in the Rosette. The open cluster, NGC2244 is comprised of hot blue stars
which emit ultraviolet light that knocks electrons away from hydrogen
atoms. When the electrons fall back, they emit the red light which
distinctively defines the glow of all emission nebulae. It is easy to
see, appearing large as the full moon. The naked eye can see the cluster
in a transparent sky like we had last night.
Hubble's Variable Nebula, NGC2261 - the variable star R Monocerotis is
the infrared source of the nebula, which is only one half of the
bi-polar outflow of this star. The core and nebula are highly variable
on a timescale of a few months or more. The star is buried in a pocket
of dust 200 AU across. The inner disk surrounding R Mon is about the
size of our own planetary system. I wonder if there are planets forming
there?
Plaskett's Star, HD47129 - the most massive binary star ever
discovered. Situated 50 million miles apart or about half the earth/sun
distance, the companion orbits every 14 days. Comprised of two O stars,
the total mass of the system is that of 100 suns. Plaskett's star is
likely a part of NGC2244 - the central cluster of the Rosette Nebula.
Mag 6, visible in binoculars one degree north of the Rosette Nebula
NGC2264 and S Monocerotis - The region around the 4.7 magnitude type O
star S Monocerotis is a fascinating mixture of red fluorescent hydrogen
and dark, obscuring dust lanes. Some dust patches are close enough to
bright stars to reflect light from them. Some of the wispy tendrils of
nebulosity are Herbig-Haro objects, jets of matter ejected from
newly-formed stars still hidden within the nebula. About 250 stars have
been recognised as members of NGC 2264 which is 2700 light years
distant. At the eyepiece, we see the mag 3.9 Christmas Tree cluster
with S Mon as the tree trunk. The cluster is surrounded by emission
nebula and under excellent transparent skies, the elusive Cone Nebula
may be visible. But not to the observers at Lake Sonoma. Some of us did,
however, see some of the wispy Herbig-Haro objects visible as
horizontal streaks in the nebulae below S Monocerotis.
Trumpler 5 - makes a triangle with Hubble's Variable Nebula, S Mon and
nebulosity. Tr 5 is an faint open cluster, 125 million years old.
NGC2236, mag 11.09 open cluster looked like a snail, an upside down curl
of 50 stars with two pairs of brighter stars, which I could imagine were
the snails antennae and ugg, slime trail. Several people came over for
a look at this one. Nice!
NGC2251 and NGC2254 are bisected by a line of bright stars reminiscent
of the Coathanger asterism, Collinder 399. If you have Millenium Star
Atlas, check out page 227 to see what I mean. I kept bumping into the
line of stars, so it was easy to differentiate larger mag 7.3 NGC2251
from smaller mag 9.7 NGC2254. NGC 2254 is 2.2 degrees south of the
Christmas Tree cluster. Much smaller NGC 2254 is a degree south of this.
Collinder 106, home of Plaskett's star, its brightest member is 2
degrres north of NGC 2252, another open cluster
FU stars - yes I am talking FU Orionis objects. These are young
Sun-like stars which are temporarily acrreting material at rapid rates
from their surrounding disks of gas and dust. They brighten by a hundred
times, stay bright for a century and fade again. The are a violent
subclass of T Tauri stars. Each protostar probably goes through this
sequence many times before the accretion disk and surrounding cloud are
dispersed. Steve Gottleib was showing FU Orionis in his telescope. I had
a FU star on my page 227 project too. I resisted the urge to say
something silly, observing being a very unsilly hobby. But I called
everyone over to see my FU too. :-) FU Monocerotis, that is. There are
only ten FU Orionis objects known, and we had seen two of them at Lake
Sonoma. Both of them were reddish and surrounded with a very faint
nebulosity. FU Orionis was the AAVSO variable star of the month Feb
2002. http://www.aavso.org/vstar/vsotm/0202.stm
T, RW, RW, SV, CV, SW, BE and AX Monocerotis were other interesting
stars I checked off on Page 227 last night.
NGC2259, NGC2252, CR111, IC448, CR97, CR96, CR92, CR104, CR107, CR110
Do22, IC2169 were other open clusters in this part of the Winter Milky
Way I observed and checked off.
To end the night, I aimed at M-42 using the O-III 31mm Nagler combo, and
invited anyone over who wasn't already tired of this object. I noticed
Hydra and tried to add one to my Hickson project. I easily found Abell
1060/Hickson 48. I could see a few faint smudges here, mag 13.2 IC2597
and I suspected 48B a small round smudge with my old 9 Nagler for 222x.
A few galaxies were all I wanted to look at last night. I really
enjoyed visiting the suburbs of our own Milky Way Galaxy as described on
page 227 and adjacent pages of the Millenium Star Atlas.
Millenium Star Atlas info: http://astro.estec.esa.nl/Hipparcos/atlas.html
Date: February 22, 2003, 2002 6:45 p.m.- midnight
Location: Lone Rock Flat, Lake Sonoma, California
Lat/Long: 38 42' 54.7" , 123 02' 43.7"
Altitude: 900 ft.
Instrument: 17.5-inch f/4.5 LITEBOX reflector
Oculars: mostly 16 mm Nagler for 125 power, 82 degrees apparant f.o.v
Seeing: very good, very steady deteriorating after 10:00 p.m.
Transparency: LM 6.2 using LM Area 3: 23-Theta-Beta-U Ma, 16 stars at
8:00 p.m.but
transparancy deteriorated after 10:00 p.m.
Temps 65 degrees at dusk, 41 degrees at midnight, humidity from low 70's
to "high" aka "wet" at midnight when we packed up.
Jane
--Jane Houston Jones San Rafael, CA jane@No-Spam http://www.whiteoaks.com