{"id":2763,"date":"2023-07-03T18:56:40","date_gmt":"2023-07-03T13:26:40","guid":{"rendered":"https:\/\/nayantelrandhe.com\/?p=2763"},"modified":"2023-07-07T14:44:34","modified_gmt":"2023-07-07T09:14:34","slug":"guitar-nebula-light","status":"publish","type":"post","link":"https:\/\/nayantelrandhe.com\/index.php\/2023\/07\/03\/guitar-nebula-light\/","title":{"rendered":"A Guitar in the sky and its speeding craftsman"},"content":{"rendered":"\t\t
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Sky is a Neighbourhood<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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A Guitar in the sky and its speeding craftsman<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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by Nayan Telrandhe | July 5, 2023 \u200b| about me<\/a><\/span>\u00a0<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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The Guitar Nebula in Optical wavelength. Credit:\u00a0NASA\/STScI & Palomar Observatory 5-m Hale Telescope. Description<\/a><\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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What are you looking at?<\/h4>
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The nebulous structure in the image is commonly called the Guitar Nebula as it resembles a shape of a guitar. The shape looks like a Dreadnaught guitar with a shorter neck and a distinctly visible headstock. The structure is a result of a rapidly moving star and its interaction with the surrounding interstellar medium. The star is a Pulsar named PSR B2224+65. In fact, the star is moving so fast that it may escape our galaxy.<\/p>

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Where is it?<\/h4>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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A view of the constellation Cepheus with the pointer at the location of Guitar Nebula. <\/p>

(Screenshot from Stellarium)<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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The Guitar Nebula is associated with the Pulsar PSR B2224+65 and the name actually tells us about the Right Ascension and Declination of the source. RA and Dec are coordinates used to locate objects in the sky. So the RA is 22h<\/sup> 24m<\/sup>\u00a0 and Dec is +65\u00b0 which is somewhere in the constellation of Cepheus and close to Polaris.<\/p>

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The distance to B2224+65 (let’s call it B22) is estimated to be\u00a0 0.83 +0.17|-0.10 kpc using parallax. The distance is ~2700 light years which is almost 1\/10th <\/sup><\/span>of the distance to the centre of the Milky Way (refer a)<\/a><\/span>. The surface brightness of even the brightest parts of Guitar Nebula is low for easy observation and thus it was only discovered in\u00a01992<\/u><\/a>.<\/p>

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The star has a proper motion of 194.1\u00b10.2 milliarcseconds per year. Proper motion is a measure of the angular speed of the object in RA-Dec or similar coordinates. Knowing the distance to the star enables us to calculate the relative speed it is moving with. The results from paper\u00a0(a)<\/a><\/span> suggest a speed of ~765 kmps (0.0025 c) The speed is very high for a star. To make sense, the star is moving so fast that it will pass from one point on Earth to the diametrically opposite one in less than 17 seconds and will cover the Earth-Moon distance in less than 9 minutes. The fastest speed recorded for a manmade object is of the Parkers Space Solar probe which is supposed to reach a speed of 194 kmps. This is possible due to the spacecraft going so close to the Sun, similar to a ball falling and accelerating towards Earth. The velocity of the pulsar lies close to the plane of sky or perpendicular to our line of sight (refer b)<\/a><\/span>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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The Guitar Nebula in Optical wavelength. Credit:\u00a0NASA\/STScI & Palomar Observatory 5-m Hale Telescope. Description<\/a><\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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The Guitar parts useful for our reference are labelled – Headstock, Neck and Body<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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The image in Optical wavelengths comes from Palomar Observatory’s 5 metre Hale Telescope and NASA\/STScI. The Nebula predominantly radiates at H\u03b1 wavelength which corresponds to radiation due to the transitions between the 3rd <\/sup>and 2nd <\/sup>orbit of the Hydrogen atom. The wavelength is 656nm belonging to the red colour on the spectrum. The nebula is a result of a Bow shock<\/a><\/span> created by the Pulsar speeding through the Interstellar medium. The Pulsar has been speeding for almost 300 years leaving a trail of the observed Nebulosity to evolve. In the region of the guitar body, the formation of inflating bubbles might be due to the star passing through the medium of non-uniform density or changes in the Pulsar wind over the journey\u201d (refer c)<\/span><\/a>.<\/p>

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The guitar has a distinctly visible headstock which has higher surface brightness compared to the trailing nebula, this structure further enhances its guitar-like appearance. According to paper (d)<\/a><\/span>, bright regions of the headstock which are perpendicular to the motion of the star\u00a0have moved outwards,\u00a0<\/span>as shown in the <\/span>linked figure<\/a><\/span> from paper <\/span>(d)<\/a><\/span> as well as below. They also suggest that <\/span>some 70 years ago\u00a0<\/span>the Pulsar broke through a dense region in ISM which is behind the head of the guitar. The shock in this dense region at the end of the headstock prevents the flow of relativistic winds from the Pulsar towards the rest of the Guitar body. This explains the brightening of the headstock and prevents the wind from powering the rest of the Guitar body, thus producing the dim, elongated and narrow \u2018neck\u2019 of the Guitar.<\/span><\/p>

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The figure shows the cropped view of the headstock region from Hubble Telescope’s H\u03b1 images (1994-2020). Credits: Martijn de Vries\u00a0et al<\/em>\u00a02022\u00a0ApJ<\/em>\u00a0939<\/b> 70<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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These newly formed regions may evolve in the future to form other inflating bubbles in the nebulosity (refer d)<\/a><\/span>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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An image combining both Optical and X-ray data in the Guitar Nebula region. Jet-like features are visible in X-rays.\u00a0<\/p>

Credit: X-ray: NASA\/CXC\/UMass\/S.Johnson et al, Optical: NASA\/STScI & Palomar Observatory 5-m Hale Telescope. Source<\/a><\/span>.<\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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A silhouette of a Rockstar standing like James Hatfield with flames at one end of the guitar – generated using Microsoft Bing’s image creator. It created some more stunning results (View<\/a><\/span>). Prompt designing is a new skill to be mastered.<\/p>\n

The band Rammstein<\/a><\/span> has been famous to put on fiery shows.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Now to the best part, The observation of the region in X-rays by Chandra telescope reveals jets extending out from the Guitar headstock just like the guitars with flamethrowers or firecrackers which are used in the live performances by many rock bands. (Here it\u2019s on a Dreadnaught guitar, a rare sighting :P)<\/p>

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The star B22 sits at the tip of the headstock which can be confirmed in the X-ray image. The hot spot seen at the tip of the headstock is not necessarily the bare Pulsar surface but the synchrotron radiation from the shocked nebula around it (refer e)<\/a><\/span>. Synchrotron radiation is observed from relativistic or very fastly moving charged particles when they are accelerated perpendicular to their direction of motion, in this case, these charged particles are spiralling about the magnetic field lines. The path of such particles about these magnetic field lines looks locally helical.<\/p>

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The upper jet originating from the Pulsar is aligned at roughly 115\u00b0 with the direction of the proper motion of this Pulsar. Figure (7) from paper (b)<\/a><\/span> provides a wider field of view to get an idea of the extension of the jet-like filament away from the Nebula. According to paper (f)<\/span><\/a> this jet-like X-ray feature arises due to the leakage of high-energy electrons accelerated at the bow shock region which is formed around the Pulsar. They continue to travel along magnetic fields in the ISM. The lower jet structure is comparatively shorter than the upper which paper (f)<\/span><\/a> suggests is due to asymmetries in interaction with ISM\u2019s magnetic field.<\/p>

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Pulsar Kicks<\/h4>

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B22 is a Pulsar and it belongs to a general class of stars called \u2018The Neutron stars\u2019. Neutron stars are very dense and are remnants from core-collapse supernovae of stars a lot more massive than the sun. They are mostly composed of Neutrons hence Neutron stars. And Pulsars are a type of Neutron star which show Pulsing behaviour understood as beams of radiation coming from the star which behave similarly to the beams of a lighthouse. It goes on and off due to its rotation as we view it.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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East Cape Lighthouse, NZ looks stunning with Milky Way on a cloudy night. A queen from a night chess set?\u00a0 Credits:\u00a0<\/span>@exploringnightsky<\/a><\/span>\u00a0| Amit Kamble (His unique Astrophotography style has always been fascinating to look at)<\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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The rotating beam leads to a pulse in received radiation like from a lighthouse. Credits: M Kramer<\/a><\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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A slowed-down video showing a pulse and interpulse from Crab Pulsar which is one of the most vastly studied object in sky.\u00a0 The period of rotation of Crab Pulsar is 33 ms.
Credits: Wikipedia<\/a><\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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A small amount of population of neutron stars has been observed to be speeding with high velocities. B22 has an estimated velocity of ~765 kmps in the plane of the sky. Another example is the pulsar IGR J1104-6103 which is moving at a speed of more than 1000 km\/s (refer g)<\/span><\/a>. A trailing nebula called the lighthouse nebula is associated with this Pulsar and the associated jets are the longest yet known for an object in the Milky Way. In the X-ray image below, the star can be seen trailing away from a nebulosity which is supposed to be the remnant debris from its supernova. An asymmetry in the jets is also visible quite similar to B22, which paper (f)<\/a><\/span> suggests is due to asymmetries in interaction with ISM\u2019s magnetic field.<\/p>

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These are some more eye candies<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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