Displaying items by tag: Variable Star
The nebula patterns and brightness slowly changes over months and years from shadows of dust clouds illuminated by the star R Monocerotis, which in itself encased in a dust cloud. Discovered by William Herschel, and studied by Edwin Hubble who it is named after.
An animated sequence of yearly images of the nebula, how much is due to different processing and different scopes and camera I don't know, but changes are visible in the nebula.
Sometimes called the Oyster Nebula, NGC 1501 is a planetary nebula located in Camelopardalis (The Giraffe). The central star shed its outer layers and those layers are now illuminated by the central star. The central star is also reported to be a pulsating variable star with an extremely short period of brightness changes.
Also known as Herschel's Garnet Star is a supersized red giant star. It is among one of the larger stars known. If it was located where our Sun is, the outer layer would reach beyond the orbit of Jupiter. The lifetime of massive stars like this are measured in millions of years. Mu Cephei will most likely end as a supernova; with either a neutron star or a black hole remaining. As a (super) red giant, it varies in magnitude between 3.4 and 5.1. It is an estimated distance of 2,800 light years away. Located near the Elephant Trunk Nebula the area has many areas of dust and gas clouds nearby.
Imaged with the ED80cft refractor and the ZWO 1600 mono camera.
T Cancri is a red giant variable that gets it's deep reddish color from carbon that is dredged up from its core that forms a fine soot layer that scatters away the blue and green light, much like a sunset does. T Cancri varies in brightness from a magnitude 7.6 down to 10.5 in the green light band over a period of around 482 days. It was around magnitude 8.6 when this image was taken.
Other names for La Superba are Y CVn, and HD 110914. La Superba is a late stage red giant star, with a mass of three times that of our Sun, but with its outer layers extending out to a radius of 2.2 Astronomical units (1 AU is the distance of the Earth to the Sun). So if La Superba was at the same location as our Sun, it's outer layers would extend out to Mars. Like many red giants, it is also a variable star changing in brightness by around 1 magnitude over a 160 day cycle.
As Orion sets in the western sky, I say goodbye to one of the long period variable stars I follow until Fall when it starts rising in the east.
V Ori is a Mira type variable star that varies between 8.9 - 14.7 in V band over a period of approximately 267 days. Mira type variables are cool red giant stars that vary in brightness by over 2.5 magnitudes over periods that range from 80 to over 1000 days. The stars are in their late stage of life, fusing helium at the core and a swelling outer layer that is only weakly bound to the star. The star will eventually stop fusing, and transition to a white dwarf with a planetary nebula surrounding it. The pulsation is thought to be caused by shock waves originating from the star and traveling out through the extended shell.
Color image of V Ori taken on March 21, 2017, when it was around magnitude 9.6 in V visual band.
Light curve of V Ori, looking like it is near its peak on April 1st.
RX And is a recurring dwarf nova star located in the constellation of Andromeda. Currently classified in the class of Z Camelopardalis variable stars, it consists of a white dwarf with an accretion disk siphoning matter from a secondary dwarf star. Once the accretion disk reaches a certain threshold, it becomes very bright until it can slowly cool back down. Usually this cycle takes from 10-13 days for RX And, but occasionally it gets stuck in a bright mode for periods for days to even years.
As part of an AAVSO optical monitoring campaign in support of Chandra X-Ray observations, I've been taking photometric measurements once a night. The star normally varies from as dim as 14.8 to as bright as 10.3 magnitudes. With a quick rise time in under 24 hours, sunscreen would be an essential item for anyone near this star system. My exposure times went from 480 seconds at its dimmest to 50 seconds near its brightest. All images were taken through a "V" filter which is a standard green band pass filter used for observations with the 80 mm refractor.
Image taken the morning of September 7, 2016. It's magnitude was around 14.34 at the time, or about the same as the other stars near it. I needed an exposure time of at least 480 seconds to collect enough signal for an accurate reading.
By the morning of September you can see that now the star is much brighter than its nearest stars. It was then at a magnitude of 11.31 and using an image exposure of 50 seconds to keep from saturating the ccd pixels. The actual rise time took less than 24 hours to brighten to 11th magnitude.
An AAVSO chart of observations of RX And by different users, with my observations marked by crosshairs. It's easy to see the fast rise and fall times of the brightness changes.
It's been an interesting project for me.
KIC 8462852 is still in the news. KIC 8462852 is a F class star located in the constellation of Cygnus. At a magnitude 11.7, its only visible in telescopes, and is located some 1480 light years away. Often called Tabby's star after Tabetha Boyajian, the lead author on a paper investigating its unusual light curve. The star's unusual light curve was first discovered by citizen scientists as part of the Planet Hunters project examining data from the Kepler space telescope.
The light curve shows small random dips in brightness and a large dip in brightness in what appears to be around a 750 day cycle. The large dip can dim the star as much as 22%, which would take a very large object dimming almost half the star.
Several theories have been suggested including a swarm of disintegrating comets, a planetary debris field, that the star is younger than it appears, and may still have material coalescing around it, and finally, an alien mega-structure. So far, no evidence has been found supporting any of these hypothesis. Even SETI has found no signals from this star system. Follow up monitoring will hopefully shed more light on what is causing the dips in light.
One study found a long term gradual fading of the star based on a century worths of photographic plates which would be unusual for this type of star, but of course another study disputes this based on errors of extracting magnitudes from photographic plates.
My image was taken back in Oct 2015, but with Cygnus in the early morning sky now, hopefully I can revisit this interesting star.
Deep in the star fields of Aquila lies SS 433 aka V1343 Aquilae. Discovered in 1977, researchers noticed spectral shifts alternating between red and blue shifts. The star is also embedded in a supernova remnant, and is also a powerful producer of x-Rays.
The star system consists of an A type star orbiting either a neutron star or a black hole. The companion star loses material to the other object forming an accretion disc that is subject to extreme heating as it spirals in. In the process giving off intense x-rays and jets of material above and below the accretion disc. These jets precess around in a period of 163 days, and travel at 26% the speed of light.
The two object orbit each other with a period of 13 days and is located 18,000 light years away. Astrophysicists call the object a micro-quasar.
I also preformed a photometric observation and came up with a magnitude of 14.46 in the "v" band and uploaded it to AAVSO.
300 second exposures through R/G/B filters with the Ed80CFT refractor for the color image, and a 600 second exposure through a V filter for the photometric observation.