APOD: Supernova in NGC 2525 (2020 Oct 23)

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APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by APOD Robot » Fri Oct 23, 2020 4:06 am

Image Supernova in NGC 2525

Explanation: Big, beautiful, barred spiral galaxy NGC 2525 lies 70 million light-years from the Milky Way. It shines in Earth's night sky within the boundaries of the southern constellation Puppis. About 60,000 light-years across, its spiral arms lined with dark dust clouds, massive blue stars, and pinkish starforming regions wind through this gorgeous Hubble Space Telescope snapshot. Spotted on the outskirts of NGC 2525 in January 2018, supernova SN 2018gv is the brightest star in the frame at the lower left. In time-lapse, a year long series of Hubble observations followed the stellar explosion, the nuclear detonation of a white dwarf star triggered by accreting material from a companion star, as it slowly faded from view. Identified as a Type Ia supernova, its brightness is considered a cosmic standard candle. Type Ia supernovae are used to measure distances to galaxies and determine the expansion rate of the Universe.

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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by Ann » Fri Oct 23, 2020 6:45 am

As a color commentator, I obviously find it hugely interesting that supernovas type Ia are blue in color. Not extremely blue, more like the color of Vega, with a B-V near zero at maximum. But since the overall color of galaxies is (practically) never that blue, supernovas type Ia look blue when seen against the background of their galaxies.

















By contrast, core-collapse supernovas are not always blue (sometimes not at all).






















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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by Misha » Fri Oct 23, 2020 8:11 am

Great photo, thanks. Could you please explain why the diffraction pattern of the supernova is so different from diffraction patterns of all other bright stars on this photo. Thank you.

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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by Chris Peterson » Fri Oct 23, 2020 1:11 pm

Misha wrote:
Fri Oct 23, 2020 8:11 am
Great photo, thanks. Could you please explain why the diffraction pattern of the supernova is so different from diffraction patterns of all other bright stars on this photo. Thank you.
The data for the SN appears to have been collected in a single imaging session, while the data for the galaxy as a whole was probably collected in multiple sessions, where the telescope moved between. HST images have cross-shaped diffraction spikes. If you look at the stars which produce them, you can see that all have four different sets of such spikes, at different rotations, consistent with the image having been made using four filters collected at four times.
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by neufer » Fri Oct 23, 2020 1:42 pm

https://en.wikipedia.org/wiki/NGC_2525 wrote:
Click to play embedded YouTube video.
Click to play embedded YouTube video.


<<NGC 2525 is a barred spiral galaxy located in the constellation Puppis. It is located at a distance of about 70 million light years from Earth, which, given its apparent dimensions, means that NGC 2525 is about 60,000 light years across. It was discovered by William Herschel on February 23, 1791.

The galaxy has a bar and two main spiral arms with high surface brightness. HII regions are observed in the arms. The brightest stars of the galaxy have apparent magnitude around 22. Its nucleus is small and bright. In the centre of the galaxy is predicted to lie a supermassive black hole whose mass is estimated to be between 1.1 and 44 million years, based on the spiral arm pitch angle.

One supernova has been observed in NGC 2525, SN 2018gv. It was discovered on 15 January 2018 at magnitude 16.5, and it was identified spectrographically as a type Ia supernova 10 to 15 days before maximum. The supernova was also observed by ATLAS on 2018 January 14.5 UT at magnitude 18.1. It reached a peak magnitude of 12.8.>>
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by johnnydeep » Fri Oct 23, 2020 3:57 pm

neufer wrote:
Fri Oct 23, 2020 1:42 pm
https://en.wikipedia.org/wiki/NGC_2525 wrote:
<<NGC 2525 is a barred spiral galaxy located in the constellation Puppis. It is located at a distance of about 70 million light years from Earth, which, given its apparent dimensions, means that NGC 2525 is about 60,000 light years across. It was discovered by William Herschel on February 23, 1791.

The galaxy has a bar and two main spiral arms with high surface brightness. HII regions are observed in the arms. The brightest stars of the galaxy have apparent magnitude around 22. Its nucleus is small and bright. In the centre of the galaxy is predicted to lie a supermassive black hole whose mass is estimated to be between 1.1 and 44 million years, based on the spiral arm pitch angle.

One supernova has been observed in NGC 2525, SN 2018gv. It was discovered on 15 January 2018 at magnitude 16.5, and it was identified spectrographically as a type Ia supernova 10 to 15 days before maximum. The supernova was also observed by ATLAS on 2018 January 14.5 UT at magnitude 18.1. It reached a peak magnitude of 12.8.>>
A mass between 1.1 and 44 million years? I presume it's a typo in the wikipedia article, but that would be quite a large range of solar masses assuming that's what those numbers really mean.
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by johnnydeep » Fri Oct 23, 2020 4:00 pm

Chris Peterson wrote:
Fri Oct 23, 2020 1:11 pm
Misha wrote:
Fri Oct 23, 2020 8:11 am
Great photo, thanks. Could you please explain why the diffraction pattern of the supernova is so different from diffraction patterns of all other bright stars on this photo. Thank you.
The data for the SN appears to have been collected in a single imaging session, while the data for the galaxy as a whole was probably collected in multiple sessions, where the telescope moved between. HST images have cross-shaped diffraction spikes. If you look at the stars which produce them, you can see that all have four different sets of such spikes, at different rotations, consistent with the image having been made using four filters collected at four times.
Neat - perfect explanation!
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by neufer » Fri Oct 23, 2020 4:57 pm

johnnydeep wrote:
Fri Oct 23, 2020 3:57 pm
neufer wrote:
Fri Oct 23, 2020 1:42 pm
https://en.wikipedia.org/wiki/NGC_2525 wrote:
<<[NGC 2525's] nucleus is small and bright. In the centre of the galaxy is predicted to lie a supermassive black hole whose mass is estimated to be between 1.1 and 44 million years, based on the spiral arm pitch angle.>>
A mass between 1.1 and 44 million years? I presume it's a typo in the wikipedia article, but that would be quite a large range of solar masses assuming that's what those numbers really mean.
Nonetheless, I found the based on the spiral arm pitch angle to provide a perfect explanation!
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by johnnydeep » Fri Oct 23, 2020 5:36 pm

neufer wrote:
Fri Oct 23, 2020 4:57 pm
johnnydeep wrote:
Fri Oct 23, 2020 3:57 pm
neufer wrote:
Fri Oct 23, 2020 1:42 pm
A mass between 1.1 and 44 million years? I presume it's a typo in the wikipedia article, but that would be quite a large range of solar masses assuming that's what those numbers really mean.
Nonetheless, I found the based on the spiral arm pitch angle to provide a perfect explanation!
So, apparently a variation in how you measure the "spiral arm pitch angle" (whatever that is) results in a large range of black hole mass estimates? I assume then that the "spiral pitch angle" is affected by the mass of the black hole, but what exactly is it?
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by neufer » Fri Oct 23, 2020 10:05 pm

johnnydeep wrote:
Fri Oct 23, 2020 5:36 pm
neufer wrote:
Fri Oct 23, 2020 4:57 pm
johnnydeep wrote:
Fri Oct 23, 2020 3:57 pm

A mass between 1.1 and 44 million years? I presume it's a typo in the wikipedia article, but that would be quite a large range of solar masses assuming that's what those numbers really mean.
Nonetheless, I found the based on the spiral arm pitch angle to provide a perfect explanation!
So, apparently a variation in how you measure the "spiral arm pitch angle" (whatever that is) results in a large range of black hole mass estimates? I assume then that the "spiral pitch angle" is affected by the mass of the black hole, but what exactly is it?
http://www.astroexplorer.org/details/apj470517f4 wrote:
Berrier et al. 2013 The Astrophysical Journal 769 132.
Further Evidence for a Supermassive Black Hole Mass-Pitch Angle Relation



<<SMBH mass–pitch angle relation for all available directly measured black hole masses and for those masses estimated indirectly via σ in our preferred sample. The fit to the SMBH mass–pitch angle relation for this extended data set is log ( MBH/ M) = (8.36 ± 0.15) − (0.076 ± 0.008) P. This fit is almost identical to the fit given in Seigar et al. (2008). Black ×'s represent data from stellar or gas dynamics (10 points), blue squares represent data from maser modeling (12 points), red triangles come from reverberation mapping data (12 points), and magenta octagons represent masses derived from the M–σ relation (20 points).
https://iopscience.iop.org/article/10.1088/0004-637X/789/2/124 wrote:

Davis et al. 2013 The Astrophysical Journal 789 (2): 124.
The black hole mass function derived from local spiral galaxies

<<Our own Milky Way has [a pitch angle] |P|=22.5º±2.5º, as measured from neutral hydrogen observations (Levineet al.2006). This implies an SMBH mass of log(M/M)=6.82±0.30 from the M–P relation, compared to a direct measurement mass estimate from stellar orbits around Sgr A* (Gillessen et al.2009) of log(M/M)=6.63±0.04. Our Milky Way is somewhat atypical in that it has four spiral arms, which is only the third most probable harmonic mode for a galaxy.>>
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by johnnydeep » Fri Oct 23, 2020 11:55 pm

neufer wrote:
Fri Oct 23, 2020 10:05 pm
johnnydeep wrote:
Fri Oct 23, 2020 5:36 pm
neufer wrote:
Fri Oct 23, 2020 4:57 pm

Nonetheless, I found the based on the spiral arm pitch angle to provide a perfect explanation!
So, apparently a variation in how you measure the "spiral arm pitch angle" (whatever that is) results in a large range of black hole mass estimates? I assume then that the "spiral pitch angle" is affected by the mass of the black hole, but what exactly is it?
http://www.astroexplorer.org/details/apj470517f4 wrote:
Berrier et al. 2013 The Astrophysical Journal 769 132.
Further Evidence for a Supermassive Black Hole Mass-Pitch Angle Relation



<<SMBH mass–pitch angle relation for all available directly measured black hole masses and for those masses estimated indirectly via σ in our preferred sample. The fit to the SMBH mass–pitch angle relation for this extended data set is log ( MBH/ M) = (8.36 ± 0.15) − (0.076 ± 0.008) P. This fit is almost identical to the fit given in Seigar et al. (2008). Black ×'s represent data from stellar or gas dynamics (10 points), blue squares represent data from maser modeling (12 points), red triangles come from reverberation mapping data (12 points), and magenta octagons represent masses derived from the M–σ relation (20 points).
https://iopscience.iop.org/article/10.1088/0004-637X/789/2/124 wrote:

Davis et al. 2013 The Astrophysical Journal 789 (2): 124.
The black hole mass function derived from local spiral galaxies

<<Our own Milky Way has [a pitch angle] |P|=22.5º±2.5º, as measured from neutral hydrogen observations (Levineet al.2006). This implies an SMBH mass of log(M/M)=6.82±0.30 from the M–P relation, compared to a direct measurement mass estimate from stellar orbits around Sgr A* (Gillessen et al.2009) of log(M/M)=6.63±0.04. Our Milky Way is somewhat atypical in that it has four spiral arms, which is only the third most probable harmonic mode for a galaxy.>>
Thanks! So, in common terms, the tighter the spiral arms (that is, the smaller the pitch angle), the larger the black hole, and a difference in pitch angle of only about 10 degrees results in about a 10x difference in black hole size.
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by Ann » Sat Oct 24, 2020 8:01 pm

How irritating! Two of the pictures I posted have diappeared. I'm posting them again as attachments.

Supernova PTF11kx of type Ia.png
Supernova PTF11kx of type Ia. Image Credit: B.J. Fulton, LCOGT
Supernova 1993J in galaxy M81.png
Supernova 1993J of type II in galaxy M81. Photo: T. Lombry.














So as you can see, supernova PTF11kx was blue because it was of type Ia, whereas supernova 1993J was non-blue because it was of type II.

Ann
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by neufer » Mon Nov 02, 2020 8:49 pm

Click to play embedded YouTube video.


:arrow: A "Complex Fibonacci spiral" is a pseudo-logarithmic spiral that grows outward for every 180 degrees (i.e., π radians) of rotation by an oscillating growth factor of [Fn+1/Fn]...

hence, an oscillating pitch angle
of arctan[ln(Fn+1/Fn)/π]] degrees.

Code: Select all

F(n+1)/F(n)	    pitch angle
-----------------------------------------
1/1		    00.00º
2/1		    12.44º
3/2		     7.35º
5/3		     9.24º
8/5		     8.51º
13/8		     8.79º
21/13		     8.68º
https://en.wikipedia.org/wiki/Logarithmic_spiral wrote:
<<Our own galaxy, the Milky Way, has several spiral arms, each of which is roughly a logarithmic spiral with pitch angle of about 12º (i.e., an exponential growth rate of 1.95 for every 180 degrees).>>
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by Ann » Tue Nov 03, 2020 5:49 am

neufer wrote:
Mon Nov 02, 2020 8:49 pm
https://en.wikipedia.org/wiki/Logarithmic_spiral wrote:
<<Our own galaxy, the Milky Way, has several spiral arms, each of which is roughly a logarithmic spiral with pitch angle of about 12º (i.e., an exponential growth rate of 1.95 for every 180 degrees).>>

















Very interesting, Art. Do astronomers think that the pitch angle of the arms reflect the overall (or central?) mass of the galaxy, so the looser the arms, the lower the mass?

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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by neufer » Tue Nov 03, 2020 3:37 pm

Ann wrote:
Tue Nov 03, 2020 5:49 am

Very interesting, Art. Do astronomers think that the pitch angle of the arms reflect the overall (or central?) mass of the galaxy, so the looser the arms, the lower the mass?
There is some indication of that. However, there is an awful lot of scatter (& wide error bars) in those logarithmic spiral pitch angle plots (with most of the angles lying between 5º & 20º). :arrow:

I'm just curious on how closely the "complex Fibonacci spiral" with its varying 0º to 12.5º pitch angle fits the spiral arms of barred spirals like the Milky Way:
---------------------------------------------------------------------
A "Complex Fibonacci spiral" is a pseudo-logarithmic spiral that grows outward for every 180 degrees (i.e., π radians) of rotation by an oscillating growth factor of [Fn+1/Fn]; hence, an oscillating pitch angle of arctan[ln(Fn+1/Fn)/π] degrees.

Code: Select all

F(n+1)/F(n)	    pitch angle
-----------------------------------------
1/1		    00.00º
2/1		    12.44º
3/2		     7.35º
5/3		     9.24º
8/5		     8.51º
13/8		     8.79º
21/13		     8.68º
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Re: APOD: Supernova in NGC 2525 (2020 Oct 23)

Post by Fred the Cat » Fri Oct 01, 2021 3:42 pm

In trying to comprehend this paper, it sparks a super novel way to think of supernovae. :thumb_up:
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Dark matter is such a WIMP, it couldn't fight its way out of a wet paper bag!

Post by neufer » Fri Oct 01, 2021 6:23 pm

https://en.wikipedia.org/wiki/Dark_matter#Indirect_detection wrote:
<<A few of the dark matter particles passing through the Sun or Earth may scatter off atoms and lose energy. Thus dark matter may accumulate at the center of these bodies, increasing the chance of collision/annihilation. This could produce a distinctive signal in the form of high-energy neutrinos. Such a signal would be strong indirect proof of WIMP dark matter. High-energy neutrino telescopes such as AMANDA, IceCube and ANTARES are searching for this signal.>>
Fred the Cat wrote:
Fri Oct 01, 2021 3:42 pm

In trying to comprehend this paper, it sparks a super novel way to think of supernovae. :thumb_up:
  • So where are these dim sub-Chandrasekhar mass white dwarf supernova
    and why haven't they decimated the white dwarf population :?:
https://en.wikipedia.org/wiki/Chandrasekhar_limit wrote:
<<A strong indication of the reliability of Chandrasekhar's formula is that the absolute magnitudes of supernovae of Type Ia are all approximately the same; at maximum luminosity, MV is approximately −19.3, with a standard deviation of no more than 0.3. A 1-sigma interval therefore represents a factor of less than 2 in luminosity. This seems to indicate that all type Ia supernovae convert approximately the same amount of mass to energy.

In April 2003, the Supernova Legacy Survey observed a type Ia supernova, designated SNLS-03D3bb, in a galaxy approximately 4 billion light years away. According to a group of astronomers at the University of Toronto and elsewhere, the observations of this supernova are best explained by assuming that it arose from a white dwarf that had grown to twice the mass of the Sun before exploding. They believe that the star, dubbed the "Champagne Supernova" may have been spinning so fast that a centrifugal tendency allowed it to exceed the limit. Alternatively, the supernova may have resulted from the merger of two white dwarfs, so that the limit was only violated momentarily. Nevertheless, they point out that this observation poses a challenge to the use of type Ia supernovae as standard candles.

Since the observation of the Champagne Supernova in 2003, several more type Ia supernovae have been observed that are very bright, and thought to have originated from white dwarfs whose masses exceeded the Chandrasekhar limit. These include SN 2006gz, SN 2007if, and SN 2009dc. The super-Chandrasekhar mass white dwarfs that gave rise to these supernovae are believed to have had masses up to 2.4–2.8 solar masses. One way to potentially explain the problem of the Champagne Supernova was considering it the result of an aspherical explosion of a white dwarf. However, spectropolarimetric observations of SN 2009dc showed it had a polarization smaller than 0.3, making the large asphericity theory unlikely.>>
Art Neuendorffer