Monday, July 13, 2015

Pluto

Pluto is getting a huge amount of press from NASA
due to the new Horizons probe's closest approach to pluto tomorrow. 
latest images can be seen here

Here's pluto back when it was still a planet in July 2006:



because of it's great distance, 
both visually, and photographically from earth, 
pluto is just another white dot in a field of stars
which can be distinguished only by the fact that it moves across the stars (in this case the images were taken over several different nights).  

here's a recent image by fellow OCastronomers member Tom Munnecke

pluto has 5 known moons, perhaps more to come.  it's largest, charon has half the diameter of pluto.  As a result, the center of mass of the system (and their combined orbit) lies outside of pluto; they orbit eachother (one of the less valid reasons for demoting pluto)

The book
How I Killed Pluto and Why It Had It Coming by Mike Brown
gives an interesting account of why pluto should not be a planet (eccentric orbit, small size, etc), pointing out the fact that there were a number of asteroids (ceres etc) that had been planets, but were later demoted.  credit is due to the astronomical societies for waiting 5 years after the death of Clyde Tombaugh, it's discoverer, before demoting it.  credit is also due to Mike Brown who helped demote it, having discovered (with his team) 2 more "transneptunian objects".  Had he made the case for pluto's planet-hood, he would have made the case for his discoveries, becoming the only living planet discoverer, and the only one to have discovered more than one.  
It also gives a remarkably restrained account of one of the slimier moves in the astronomy world: a group from Spain saw an abstract title for an upcoming meeting,  peeked at the server logs, determining the location of the object mike brown was studying, then claimed the discovery as their own, without so much as a reference to the US group.  
The book is actually a good read, thanks chris


Here's one of his discoveries:

Transneptunian object 2005 FY9 a/k/a Easter bunny passing egg shaped galaxy ngc 4314 2/22/2006.  
This dwarf planet is now named Makemake (god of fertility in the mythology of the Rapa Nui people of Easter Island).  discovered around easter when his wife was pregnant...

Friday, July 3, 2015

revisiting the expanding crab

here's my biennial addition to the crab nebula expansion from 2006 to 2014(15)
it appears as though the pulsar wind is outstripping the filaments, especially mid lower left:
M1-2006-2014-rgb-500.gif
RGB only as my earlier images were limited.
a wider version shows a high proper motion star lower left.
Here’s is a composite of LRGB plus a touch of OIII luminance for the outer shell and faint jet up top as well as a 540x50nm filter for the pulsar wind (I finally switched to north up):
M1-2014-LOIIIRGB.jpg
In year’s past, the pulsar wind appeared bluish, but this was using an LPR fliter which knocks out a chunk of the spectrum in green including the pulsar wind.
This year I used astrodon RGB filters without an LPR filter and excalibrator for color balance, so I think this is more “accurate”.
Yes, this is actually my first LRGB CCD image with RGB from a mono camera
what's the pulsar wind?
this:
M1-2014-pular-wind.jpg
M1-2014-RGB-pulsar-wind-blink.gif
I used a “green continuum” filter with a bandwidth of 50 nm centered at 540 nm which avoids the major emission lines of the crab nebula,
isolating the glowing pulsar wind caused by electrons accelerating in the rapidly rotating magnetic field of the spinning neutron star/pulsar.
the pulsar wind glow, rather than the central star, excites the gas filaments
which in turn give off the emission line signal.

Here’s the OIII:
M1-2014-OIII.jpg
Which gives a nicely defined outer shell, and a hint of the “jet” on top
Note that the upper right corner is a bit weak in OIII, the crab is stronger in broad band emissions there, not sure why.

And lastly here it is in red white and blue in honor of the date of the crab nebula supernova on July 4th:
M1-2014-RWB-800.jpg
Red is mapped to, um red, the continuum filter to white, and OIII to blue with an emphasis on the pulsar wind.
Maybe I can talk the APOD folks into posting it for July 4th

I captured the pulsar wind 2 years ago with a filter that had a narrower bandwidth and lower transmission, but failed to demonstrate any short term motion associated with the pulsar wind, which I caught with luminance in 2010.
Unfortunately, it was a bit of a fail as I was able to demonstrate very little if any motion with the new broader higher transmission continuum filter:
M1-2014--540-crop-motion.gif
note slight expansion in the clear area around the central neutron star
The motion was a bit more evident on L/RGB than the continuum filter
M1-2014--linear-luminance-crop-motion.gi
(comparing 4 nights 2 luminance and 2 RGB pseudoluminance)
An analysis of the two RGB nights seemed to indicate the motion was better in the red channel, (subtle difference due to seeing/refraction?)
Not sure if that means it’s Ha/NII or red continuum…


Speaking of moving things I caught minor planet 541 Deborah (discovered by Max Wolf on August 4, 1904) on color images.  The seeing was so bad (FWHM>7) that I actually threw the subs out.
M1-2014-RGB-deborah.jpg


found another moving object, very slow satellite or fast minor planet trailing in 10 minute subs at .8”/px:
m1-11-27-14-LX200-qsi-H545x50-bx2-001_60
at
05 34 32
22 01 00
on 2014 11 28 8:25:35 UT
MP checker indicates this is (2945) Zanstra      
05 34 31.8 +22 01 00  16.4   0.0W   0.0S    33-     0+
a main-belt asteroid discovered on September 28, 1935 by H. van Gent

also see older posts:
http://astrowhw.blogspot.com/2013/07/4th-of-july-supernova-revisited-crab.html
http://astrowhw.blogspot.com/2013/07/crab-nebula-expansion.html

and this animation

2015
11/26/14-3/9/15
8" LX200R, SX Trius 694 and QSI 660 binned x2 to 0.8"/px, ASA DDM60
astrodon LRGB E SERIES GEN-II, OIII 5 nm, chroma 540x50 nm filter (greenish continuum)
L 346 x 1 min
red 33 x 4 min, green 22 x 4 min, blue 22 x 4 min (included as pseudoluminance)
OIII 24 x 20min
540x50 53 x 5min, 56 x 10min

2013
1/12/2013-3/4/2013
8" LX200R @ 0.6"/px, SX AO, Astrodon OIII 5nm, IDAS LPR filters SX H9/H9C
RGB(IDAS) 14x20 min, luminance 35x5 min with idas, 35x5 min unfiltered, plus RGB pseudoluminance
OIII 19x20 min

2010
12/6/2010-2/6/2011
8" LX200R, SX AO, Astrodon OIII 5nm IDAS LPR, SX H9/H9C
RGB 31x20 min, luminance 205x5 min plus RGB pseudoluminance, OIII 47x10 min binnned x2

2008
forgot the details there was too much star trailing for me to complete the initial processing.
aborted HaRGB

2006
1/2,3,5/06
nexstar 8 GPS, IDAS LPR filter, f/6.3 FR, SXV H9C
120x1 min, 240x30 sec (unguided)