Rainbow Star (May be Sirius)

Off topic discourse and banter encouraged.
dineshns
Asternaut
Posts: 6
Joined: Sat Aug 17, 2019 8:18 pm

Rainbow Star (May be Sirius)

Post by dineshns » Wed Apr 06, 2022 2:50 am

I captured a very colorful star assuming it is Sirius, But not sure.
Click to play embedded YouTube video.

User avatar
Ann
4725 Å
Posts: 11990
Joined: Sat May 29, 2010 5:33 am

Re: Rainbow Star (May be Sirius)

Post by Ann » Wed Apr 06, 2022 6:27 am

dineshns wrote: Wed Apr 06, 2022 2:50 am I captured a very colorful star assuming it is Sirius, But not sure.
Click to play embedded YouTube video.
I don't think it is Sirius, because the star you filmed is quite red. Of course, if Sirius is low in the sky, it will be reddened.

I think that the star you filmed could possibly be Arcturus.

Click to play embedded YouTube video.
Sirius twinkling.
Click to play embedded YouTube video.
Arcturus twinkling.

I have once seen Arcturus twinkle in a manner similar to the star you have filmed. Arcturus seemed to sparkle and emit strong twinkles of red and green.

Ann
Color Commentator

User avatar
Chris Peterson
Abominable Snowman
Posts: 16588
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: Rainbow Star (May be Sirius)

Post by Chris Peterson » Wed Apr 06, 2022 2:37 pm

Ann wrote: Wed Apr 06, 2022 6:27 am
dineshns wrote: Wed Apr 06, 2022 2:50 am I captured a very colorful star assuming it is Sirius, But not sure.
Click to play embedded YouTube video.
I don't think it is Sirius, because the star you filmed is quite red. Of course, if Sirius is low in the sky, it will be reddened.

I think that the star you filmed could possibly be Arcturus.

Click to play embedded YouTube video.
Sirius twinkling.
Click to play embedded YouTube video.
Arcturus twinkling.

I have once seen Arcturus twinkle in a manner similar to the star you have filmed. Arcturus seemed to sparkle and emit strong twinkles of red and green.

Ann
I'd go with Sirius. That's exactly what it looks like in a long exposure much of the time, being very bright and often low in the sky for northern observers. You can't really say anything about the color of the star here.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Ann
4725 Å
Posts: 11990
Joined: Sat May 29, 2010 5:33 am

Re: Rainbow Star (May be Sirius)

Post by Ann » Wed Apr 06, 2022 4:11 pm

Chris Peterson wrote: Wed Apr 06, 2022 2:37 pm
I'd go with Sirius. That's exactly what it looks like in a long exposure much of the time, being very bright and often low in the sky for northern observers. You can't really say anything about the color of the star here.

Sirius is certainly the "twinkliest" star in the sky. It sparkles in all colors of the rainbow, but it is indeed dominated by bluish and greenish hues.

Sirius is always relatively low in the sky from the latitudes of Sweden, but I have never seen Sirius look obviously yellow in the sky. Still, I realize that atmospheric conditions can affect Sirius to make it look yellow. I have also never seen a color picture where Sirius looks yellow, but I realize that a photo of a yellow-looking Sirius can be processed into an image where Sirius looks white or blue.

We should probably ask the photographer. Was the star that he filmed high or low in the sky? Had the sunset some hours before been unusually red, so that the atmosphere might have been unusually dusty?


Take a look at the picture above. It is interesting that Rigel and Betelgeuse are not all that "twinkly", whereas Sirius, by contrast, twinkles almost madly. It changes color as it does so, and as the series of images show, Sirius does indeed "flash red", too. But it is not, unless circumstances are very unusual, persistently dominated by red and yellowish hues.

I think that the video that dineshns posted shows us a star that is yellower in color than we expect Sirius to be. It is certainly still possible that the star is in fact Sirius, but it looks much more like a low and twinkly Arcturus to me.

Ann
Last edited by Ann on Wed Apr 06, 2022 4:29 pm, edited 1 time in total.
Color Commentator

User avatar
Chris Peterson
Abominable Snowman
Posts: 16588
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: Rainbow Star (May be Sirius)

Post by Chris Peterson » Wed Apr 06, 2022 4:28 pm

Ann wrote: Wed Apr 06, 2022 4:11 pm
Chris Peterson wrote: Wed Apr 06, 2022 2:37 pm
I'd go with Sirius. That's exactly what it looks like in a long exposure much of the time, being very bright and often low in the sky for northern observers. You can't really say anything about the color of the star here.

Sirius is certainly the "twinkliest" star in the sky. It sparkles in all colors of the rainbow, but it is indeed dominated by bluish and greenish hues.

Sirius is always relatively low in the sky from the latitudes of Sweden, but I have never seen Sirius look obviously yellow in the sky. Still, I realize that atmospheric conditions can affect Sirius to make it look yellow. I have also never seen a color picture where Sirius looks yellow, but I realize that a photo of a yellow-looking Sirius can be processed into an image where Sirius looks white or blue.

We should probably ask the photographer. Was the star that he filmed high or low in the sky? Had the sunset some hours before been unusually red, so that the atmosphere might have been unusually dusty?


Take a look at the picture above. It is interesting that Rigel and Betelgeuse are not all that "twinkly", whereas Sirius, by contrast, twinkles almost madly. It changes color as it does so, too, and as the series of images show, Sirius does indeed "flash red", too. But it is not, unless circumstances are very unusual, persistently dominated by red and yellowish hues.

I think that the video that dineshns posted shows us a star that is yellower in color than we expect Sirius to be. It is certainly still possible that the star is in fact Sirius, but it looks much more like a low and twinkly Arcturus to me.

Ann
I don't think this image shows us anything about the color of the star itself.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Ann
4725 Å
Posts: 11990
Joined: Sat May 29, 2010 5:33 am

Re: Rainbow Star (May be Sirius)

Post by Ann » Wed Apr 06, 2022 7:22 pm

dineshns wrote: Wed Apr 06, 2022 2:50 am I captured a very colorful star assuming it is Sirius, But not sure.
Click to play embedded YouTube video.
I'm not going to sway Chris in this discussion no matter what I say, but maybe I can make interested in what I say. I am, after all, the Color Commentator, and I have spent years trying to understand the colors of stars.

First of all, the star that you have filmed could be Sirius, and its glorious twinkling suggests that it is. I just find its color non-Sirius-like.

(Then again, if Sirius is really low in the sky, and the atmosphere is unusually dusty, Sirius may indeed look yellowish. Also, for whatever reason, the equipment you were using when filming the star just might have been more sensitive to yellow and red than to blue light.)

But consider this. English astrophotographer Steve Brown filmed Sirius with the star deliberately out of focus to make its varying colors stand out more. He then put together 782 twinkles of different colored light from Sirius into one single portrait of the colors of Sirius:

Katharine Schwab of Fast Company wrote about Steve Brown:

The amateur U.K.-based astrophotographer Steve Brown managed to capture that stunning spectrum of light in his photo Scintillating Sirius, which was recently shortlisted for the Insight Astronomy Photographer of the Year awards. The image is a composite created by shooting video of the star deliberately out of focus, so the light of the star shows up on film like a lens glare. Brown then chose the most vibrant, unexpected colors and put them together into a composite image. The final shot has 782 twinkles of different colored light.
As you can see, Steve Brown's composite portrait of Sirius is much bluer in color than the star in your film.

I recommend this site, where you can have some fun with the blackbody spectra and colors of Sirius and the Sun.

Ann
Color Commentator

User avatar
Chris Peterson
Abominable Snowman
Posts: 16588
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: Rainbow Star (May be Sirius)

Post by Chris Peterson » Wed Apr 06, 2022 8:17 pm

Ann wrote: Wed Apr 06, 2022 7:22 pm
Katharine Schwab of Fast Company wrote about Steve Brown:

The amateur U.K.-based astrophotographer Steve Brown managed to capture that stunning spectrum of light in his photo Scintillating Sirius, which was recently shortlisted for the Insight Astronomy Photographer of the Year awards. The image is a composite created by shooting video of the star deliberately out of focus, so the light of the star shows up on film like a lens glare. Brown then chose the most vibrant, unexpected colors and put them together into a composite image. The final shot has 782 twinkles of different colored light.
As you can see, Steve Brown's composite portrait of Sirius is much bluer in color than the star in your film
Indeed. However I don't think the method used has the slightest connection to either the visual or the long exposure appearance of Sirius under bad seeing conditions.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

dineshns
Asternaut
Posts: 6
Joined: Sat Aug 17, 2019 8:18 pm

Re: Rainbow Star (May be Sirius)

Post by dineshns » Wed Apr 06, 2022 9:00 pm

Thank you for all your replies. I am very new to the astro universe. Some answers to questions came up below.

Location : NZ (Auckland)
Time 9:30pm (Sunset around 6:00pm)
Visible in the sky from: East (a little bit to the north) is about a 30-40 degree angle above the horizon.
Environment; Clear sky no dust at all.
Based on Star Walk App: Sirius can visible from west (If I got it right

I captured this on Sunday 3rd April. After that didn't have a clear sky. Today looks good and I will try to get more info.

Thank you Again
Dinesh

User avatar
Chris Peterson
Abominable Snowman
Posts: 16588
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: Rainbow Star (May be Sirius)

Post by Chris Peterson » Wed Apr 06, 2022 9:18 pm

dineshns wrote: Wed Apr 06, 2022 9:00 pm Thank you for all your replies. I am very new to the astro universe. Some answers to questions came up below.

Location : NZ (Auckland)
Time 9:30pm (Sunset around 6:00pm)
Visible in the sky from: East (a little bit to the north) is about a 30-40 degree angle above the horizon.
Environment; Clear sky no dust at all.
Based on Star Walk App: Sirius can visible from west (If I got it right

I captured this on Sunday 3rd April. After that didn't have a clear sky. Today looks good and I will try to get more info.

Thank you Again
Dinesh
Yes, Sirius would be moderately high in the west. In the east, your options would be Arcturus (but only a few degrees above the horizon, just rising), or Spica, with an altitude of 36°.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

dineshns
Asternaut
Posts: 6
Joined: Sat Aug 17, 2019 8:18 pm

Re: Rainbow Star (May be Sirius)

Post by dineshns » Wed Apr 06, 2022 10:11 pm

Thank you Chris,

So this is not Sirius for sure. I will look for Arcturus and Spica.

Dinesh

User avatar
Ann
4725 Å
Posts: 11990
Joined: Sat May 29, 2010 5:33 am

Re: Rainbow Star (May be Sirius)

Post by Ann » Thu Apr 07, 2022 4:40 am

Dineshns, I think Arcturus is just right. It makes perfect sense that your star is Arcturus if it was low in the sky when you filmed your star.

I have seen Arcturus sparkle madly just once, but I will never forget it. It positively seemed to fire red and green flashes. Arcturus was indeed low in the sky when I saw it sparkle like that.

I think Arcturus is a likelier candidate for your star than Spica, for two reasons. First, Spica is intrinsically blue-white, whereas Arcturus is intrinsically yellow-orange. Second, Arcturus is considerably brighter in our skies than Spica. The apparent (visual) magnitude of Arcturus is −0.04, which makes it one of the brightest-looking stars in the Earth's skies. Spica, by contrast, has an apparent magnitude of +0.97, which is considerably fainter. See the List of brightest stars.

Because Arcturus is brighter in our skies than Spica, we can expect it to twinkle more.

However, if the star you filmed was 30 to 40 degrees high up in the sky, it couldn't have been Arcturus, according to what Chris said about the position of Arcturus at the time and place when you filmed your star. But I keep insisting that the star you filmed looks like Arcturus.

Ann
Color Commentator

dineshns
Asternaut
Posts: 6
Joined: Sat Aug 17, 2019 8:18 pm

Re: Rainbow Star (May be Sirius)

Post by dineshns » Thu Apr 07, 2022 10:30 pm

Ann wrote: Thu Apr 07, 2022 4:40 am Dineshns, I think Arcturus is just right. It makes perfect sense that your star is Arcturus if it was low in the sky when you filmed your star.

I have seen Arcturus sparkle madly just once, but I will never forget it. It positively seemed to fire red and green flashes. Arcturus was indeed low in the sky when I saw it sparkle like that.

I think Arcturus is a likelier candidate for your star than Spica, for two reasons. First, Spica is intrinsically blue-white, whereas Arcturus is intrinsically yellow-orange. Second, Arcturus is considerably brighter in our skies than Spica. The apparent (visual) magnitude of Arcturus is −0.04, which makes it one of the brightest-looking stars in the Earth's skies. Spica, by contrast, has an apparent magnitude of +0.97, which is considerably fainter. See the List of brightest stars.

Because Arcturus is brighter in our skies than Spica, we can expect it to twinkle more.

However, if the star you filmed was 30 to 40 degrees high up in the sky, it couldn't have been Arcturus, according to what Chris said about the position of Arcturus at the time and place when you filmed your star. But I keep insisting that the star you filmed looks like Arcturus.

Ann
Thank you Ann for helping to find out which star I filmed.

Luckily I had a clear sky after a few days. I checked with the star walk app last night, this star is about 40deg and Arcturus was just above the horizon. So I am thinking this star is Spica. The 3rd of April was 2 days after the new moon, that may be the reason I saw this many colors. I took the same picture as I did on the 3rd, But this time it is not that colorfull. This may be due to the moon being brighter.

I will check this again when on the next new moon, to see if it is the same as before or even better.

Dinesh