Tulip Nebula (SH2-101) and Cygnus X-1
Characteristics:
RA (J2000): 19h 59m 31s
Dec (J2000): +35 degrees 21' 18"
Position Angle: +1 degree
Description:
This
image represents a total exposure of 12 hours through SII, Ha, and OIII
narrowband filters, processed using the Hubble Palette (SII, red
channel; Ha, green channel; OIII, blue channel).
The
Tulip Nebula (SH2-101) is a star forming region located approximately
6,000 light years away in the constellation Cygnus. Emissions
from this region are powered by UV radiation from young, hot stars
typically found in OB3
associations, such as the O class star HDE 227018 present within
the Tulip Nebula. The
above field of view also includes the black hole Cygnus X-1, which is a
microquasar located at a distance of about 7,000 light years and is
part of an X-ray binary system containing a blue supergiant partner
(HDE 226868, aka HIP 98298 or SAO 69181). A "microquasar" is an
X-ray source typically arising from the accretion disk surrounding a
stellar mass black hole like Cyg X-1 within our galaxy (for instance),
whereas a "quasar" represents intense X-ray emission emanating from the
accretion disk surrounding a supermassive black hole in the center of a
distant galaxy outside of the Milky Way. Cygnus
X-1 was one of
the first black holes identified by its strong X-ray emission, first
detected by a suborbital sounding rocket in 1964 that was designed to
measure X-ray emissions that would have been difficult to otherwise
detect by Earth bound instruments due to atmospheric extinction (the
"X" in Cygnus X-1 stands for "X-ray", and the "1" indicates that it was
the first such X-ray emission detected in Cygnus). Cygnus X-1 has
an estimated mass of 21 solar masses, its companion star (HDE 226868)
has an estimated mass of 40 solar masses, and they orbit around each
other with a distance of only 0.2 AU and a period of 6 days. The
fact that the blue supergiant companion still exists in orbit around
Cyg X-1, as opposed to having been ejected as a result of a Type II
supernova explosion (for instance), suggests that Cyg X-1 was formed by
directly collapsing into a
black hole (as opposed to going supernova). The accretion disk
that is thought to surround Cyg X-1 is fed
by matter
gravitationally stolen from the outer layers of the companion star
HDE 226868, and the extreme
temperatures resulting from this accretion disk is what leads to the
strong
X-ray emissions characteristic of Cyg X-1. As is typical of such
accretion disks, a bipolar relativistic jet is created that is
perpendicular to the
plane of the accretion disk, creating a faint bow shock that is best
seen in the OIII channel of the above image. More
information about this region can be found here.
Photographic
Details:
Dates: July 4 and 6,
2025.
Scope: Takahashi
FSQ106 at f5 on the Skywatcher EQ6-R mount.
Autoguider: ASI178 autoguider with SvBony 30mm guidescope, focal length
120mm.
Camera: ZWO ASI294MM at -10C,
with
7 position ZWO filter wheel. Pixel size is 2.3 microns (Bin 1x1),
yielding an image scale with the FSQ (530mm focal length) of 0.90
"/pixel (well matched for my seeing of 3 arcseconds).
Camera gain set to 50 (e-gain
2.13 electrons/ADU), offset 25.
Read noise at this gain level was 2.18 electrons rms.
Filters: Baader
Ha, OIII, and SII filters; 2 inch.
Image acquisition
software: MaximDL for camera control and autoguiding; CCD
Commander for automation.
Exposures: Total
exposure 12 hours (Ha: 3 hours, 300 second subs; OIII: 5 hours, 300
second subs; SII: 4 hours, 300 second subs).
Processing:
Calibration,
integration, deconvolution (BlurXTerminator), noise reduction
(NoiseXTerminator), and Narrowband Normalization (Bill Blanshan and Mike Cranfield
Pixinsight process) in
Pixinsight; subsequent processing in Photoshop. Stars were
processed using the Ha and OIII channels along with the Foraxx script
developed by Paulyman
Astro.
Please
note: Graphics on this website may not be reproduced without
author permission.
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