Found Images: 2019 April

[bystander]

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Have you seen a great image or video somewhere that you think would make a great APOD? Nominate it for APOD! Please post as much information here as you have about the image/video with a link to any source(s) for it you know of here, and the editors will take a look.

When posting the image itself, please do not post anything larger than a thumbnail here; please honor the copyright holder's copyright.

Please keep hotlinked images under 400K.

Thank you!

<< Previously

[bystander]

Shooting the Messenger
ESO Picture of the Week | 2019 Apr 01

Image Credit: Petr Horálek/ESO

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As dusk falls, lampposts gently illuminate the curves and angles of the ESO Supernova Planetarium & Visitor Centre. Treetops are silhouetted against the fading red glow stretching along the horizon, while artificial lights cast bright pools and carve out shadowy corners, creating an atmospheric setting around ESO’s Headquarters in Garching, Germany.

The diagonal line of bright dots streaking across the sky shows the planet Mercury, which was named after the Roman messenger god. Its path is captured in multiple exposures: about 60 images taken over the course of an hour. Mercury is normally a very difficult planet to observe, largely owing to its proximity to the Sun, whose brightness easily obscures it. Seeing it from a city is especially difficult owing to light pollution.

However, on this occasion, several factors conspired to allow ESO photo ambassador Petr Horálek to capture these shots: the night was especially clear; it was just two nights before Mercury reached its greatest eastern elongation, or greatest angular distance from the Sun with respect to Earth; and the planet appeared high in the sky after sunset.

Another way to spot the Sun’s closest planet is when it transits. This will next take place on 11 November 2019. This is a very rare occurrence, and the next such transit will not occur until 2032!

[bystander]

The Largest of Its Kind
ESA Hubble Picture of the Week | 2019 Apr 01

Image Credit: ESA/Hubble & NASA, G. Piotto et al.

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Star clusters are commonly featured in cosmic photoshoots, and are also well-loved by the keen eye of the NASA/ESA Hubble Space Telescope. These large gatherings of celestial gems are striking sights — and the subject of this Picture of the Week, Messier 2, is certainly no exception.

Messier 2 is located in the constellation of Aquarius (The Water-Bearer), about 55 000 light-years away. It is a globular cluster, a spherical group of stars all tightly bound together by gravity. With a diameter of roughly 175 light-years, a population of 150 000 stars, and an age of 13 billion years, Messier 2 is one of the largest clusters of its kind and one of the oldest associated with the Milky Way.

This Hubble image of Messier 2’s core was created using visible and infrared light. Most of the cluster’s mass is concentrated at its centre, with shimmering streams of stars extending outwards into space. It is bright enough that it can even be seen with the naked eye when observing conditions are extremely good.

[starsurfer]

LDN 43
http://www.astrophoton.com/LBN0007.htm
Copyright: CEDIC
Processing: Bernhard Hubl

[Ann]

The Largest of Its Kind
ESA Hubble Picture of the Week | 2019 Apr 01

Image Credit: ESA/Hubble & NASA, G. Piotto et al.

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Star clusters are commonly featured in cosmic photoshoots, and are also well-loved by the keen eye of the NASA/ESA Hubble Space Telescope. These large gatherings of celestial gems are striking sights — and the subject of this Picture of the Week, Messier 2, is certainly no exception.

Messier 2 is located in the constellation of Aquarius (The Water-Bearer), about 55 000 light-years away. It is a globular cluster, a spherical group of stars all tightly bound together by gravity. With a diameter of roughly 175 light-years, a population of 150 000 stars, and an age of 13 billion years, Messier 2 is one of the largest clusters of its kind and one of the oldest associated with the Milky Way.

This Hubble image of Messier 2’s core was created using visible and infrared light. Most of the cluster’s mass is concentrated at its centre, with shimmering streams of stars extending outwards into space. It is bright enough that it can even be seen with the naked eye when observing conditions are extremely good.

The claim that the ESA/Hubble picture of M2 was created using visible and infrared light does not seem to be correct. According to the ESA/Hubble page, the filters used for the image appear to have been two ultraviolet ones and an optical blue one.

Such a choice of filters is very unusual, and I have to wonder what prompted it. Presumably the object was to look for ultraviolet stars, and there seems to be a lot of them, particularly in the center of this globular.

Ann

[starsurfer]

The Largest of Its Kind
ESA Hubble Picture of the Week | 2019 Apr 01

Image Credit: ESA/Hubble & NASA, G. Piotto et al.

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Star clusters are commonly featured in cosmic photoshoots, and are also well-loved by the keen eye of the NASA/ESA Hubble Space Telescope. These large gatherings of celestial gems are striking sights — and the subject of this Picture of the Week, Messier 2, is certainly no exception.

Messier 2 is located in the constellation of Aquarius (The Water-Bearer), about 55 000 light-years away. It is a globular cluster, a spherical group of stars all tightly bound together by gravity. With a diameter of roughly 175 light-years, a population of 150 000 stars, and an age of 13 billion years, Messier 2 is one of the largest clusters of its kind and one of the oldest associated with the Milky Way.

This Hubble image of Messier 2’s core was created using visible and infrared light. Most of the cluster’s mass is concentrated at its centre, with shimmering streams of stars extending outwards into space. It is bright enough that it can even be seen with the naked eye when observing conditions are extremely good.

The claim that the ESA/Hubble picture of M2 was created using visible and infrared light does not seem to be correct. According to the ESA/Hubble page, the filters used for the image appear to have been two ultraviolet ones and an optical blue one.

Such a choice of filters is very unusual, and I have to wonder what prompted it. Presumably the object was to look for ultraviolet stars, and there seems to be a lot of them, particularly in the center of this globular.

Ann

Tell the NASA guys that they got the caption wrong.

[starsurfer]

M65 and M66
http://www.karelteuwen.be/photo_page.ph ... 8&album=18
Copyright: Karel Teuwen

[bystander]

The Largest of Its Kind
ESA Hubble Picture of the Week | 2019 Apr 01

The claim that the ESA/Hubble picture of M2 was created using visible and infrared light does not seem to be correct. According to the ESA/Hubble page, the filters used for the image appear to have been two ultraviolet ones and an optical blue one.

Such a choice of filters is very unusual, and I have to wonder what prompted it. Presumably the object was to look for ultraviolet stars, and there seems to be a lot of them, particularly in the center of this globular.

Tell the NASA guys that they got the caption wrong.

It's not NASA. It's ESA.

[Ann]

Tell the NASA guys that they got the caption wrong.

I just wrote to the ESA people. Let's see if anything happens.

Ann

[starsurfer]

NGC 5907
https://www.hansonastronomy.com/ngc-5907-1
Copyright: Mark Hanson

[starsurfer]

Dr 15
https://www.astrobin.com/396048/
Copyright: Marcel Drechsler/Chilescope

[starsurfer]

M17
http://www.cielaustral.com/galerie/photo92.htm
Copyright: Ciel Austral

[starsurfer]

Cat's Paw Nebula (NGC 6334)
https://www.eso.org/public/news/eso1003/
Copyright: ESO

Click to view full size image

[starsurfer]

NGC 6559
http://www.astrostudio.at/1_Deep%20Sky% ... c13a76fcc5
Copyright: Gerald Rhemann

[starsurfer]

IC 444
http://afesan.es/Deepspace/slides/Vdb%2 ... ni%29.html
Copyright: Antonio Sánchez

This area is near the supernova remnant IC 443.

[bystander]

Blue Rejuvenation
ESA Hubble Picture of the Week | 2019 Apr 08

Credit: ESA/Hubble & NASA, G. Piotto et al

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Globular clusters are inherently beautiful objects, but the subject of this NASA/ESA Hubble Space Telescope image, Messier 3, is commonly acknowledged to be one of the most beautiful of them all.

Containing an incredible half a million stars, this eight-billion-year-old cosmic bauble is one of the largest and brightest globular clusters ever discovered. However, what makes Messier 3 extra special is its unusually large population of variable stars — stars that fluctuate in brightness over time. New variable stars continue to be discovered in this sparkling stellar nest to this day, but so far we know of 274, the highest number found in any globular cluster by far. At least 170 of these are of a special variety called RR Lyrae variables, which pulse with a period directly related to their intrinsic brightness. If astronomers know how bright a star truly is based on its mass and classification, and they know how bright it appears to be from our viewpoint here on Earth, they can thus work out its distance from us. For this reason, RR Lyrae stars are known as standard candles — objects of known luminosity whose distance and position can be used to help us understand more about vast celestial distances and the scale of the cosmos.

Messier 3 also contains a relatively high number of so-called blue stragglers, which are shown quite clearly in this Hubble image. These are blue main sequence stars that appear to be young because they are bluer and more luminous than other stars in the cluster. As all stars in globular clusters are believed to have formed together and thus be roughly the same age. Only a difference in mass can give these stars a different colour: a red, old star can appear bluer when it acquires more mass, for instance stripping it from a nearby star. The extra mass changes it into a bluer star, which makes us think it is younger than it really is.

[Ann]

Spacetelescope.com wrote:

Messier 3 also contains a relatively high number of so-called blue stragglers, which are shown quite clearly in this Hubble image.

Click to view full size image

Color-magnitude diagram of cluster M3.
Blue stragglers are labelled BS.
Source: https://www.researchgate.net/figure/Col ... _237669173

Click to view full size image

Blue stragglers (at top left) in globular cluster NGC 6397.
Photo: Hubble. APOD on Feb 20, 2002.

Blue stragglers are not easy to spot, because they are both less blue and less bright than the blue horizontal branch stars.

Look at the color-magnitude diagram of globular cluster M3. The thick black "river" at bottom center, labelled MS, is the main sequence stars. TO means the turnoff point, where the stars have used up their core hydrogen and leave the main sequence and turn into red giants. But not all stars "turn right" at the turnoff point. The blue stragglers have, for some reason, not exhausted their core hydrogen, so they shine brighter and bluer than all other main sequence stars in the globular cluster. (It is believed that the blue stragglers have accreted matter from another star, perhaps to the point of totally absorbing it.)

But as I said, the blue stragglers are both less blue and less bright than the blue horizontal stars, labelled HB in the diagram at left. (If you are wondering, the two slashes denote the part of the horizontal branch where you find the RR Lyrae variables - see this APOD.)

Here is a colorized color-magnitude diagram of another globular cluster - which was the APOD on February 23, 2001 - which gives you an idea of the relative color and brightness of blue straggler stars.

Look at the Hubble picture of globular cluster NGC 6397. Can you see a short but undeniable "line" or "chain" of rather small bluish stars at upper left? They are blue stragglers. They have sunk to the center of this globular, because they are more massive than almost all other stars in NGC 6397, at two or possibly three solar masses. But note that they are fainter than the other blue stars in the cluster, the blue horizontal branch stars.

A labelled version of the Hubble image of M3, pointing out a few blue stragglers, would be nice!

Ann

[starsurfer]

Hammer Nebula (VBRC 5)
http://members.pcug.org.au/~stevec/VBRC ... 0_RC14.htm
Copyright: Steve Crouch

[starsurfer]

NGC 3718 and NGC 3729
http://www.distant-lights.at/ngc3718-2017_04_24.htm
Copyright: Thomas Henne

Click to view full size image

[starsurfer]

IC 5332
http://paulhaese.net/IC5332.html
Copyright: Paul Haese

[starsurfer]

NGC 300
http://www.astrobin.com/315417/B/
Copyright: Tommy Nawratil

[felopaul]

LMC

1060 hours frames for this picture

shoot during 2 years (5 months/year),
it's a world record !
.

Click to view full size image

full size : http://www.cielboreal.com/galerie/photo95f.jpg

mosaic 16 plans (4x4) 17000 pixels x 17000 pixels

http://www.cielaustral.com
Copyright: Team CielAustral with J.C CANONNE, N.OUTTERS, P. BERNHARD, D. CHAPLAIN & L. BOURGON

[starsurfer]

LMC

1060 hours frames for this picture

shoot during 2 years (5 months/year),
it's a world record !
.

Click to view full size image

full size : http://www.cielboreal.com/galerie/photo95f.jpg

mosaic 16 plans (4x4) 17000 pixels x 17000 pixels

http://www.cielaustral.com
Copyright: Team CielAustral with J.C CANONNE, N.OUTTERS, P. BERNHARD, D. CHAPLAIN & L. BOURGON

This is amateur astrophoto of the year! I love seeing the amazing detail in all the different nebulae, this is a record breaking image! Well done!

[starsurfer]

NGC 6958
http://www.chart32.de/index.php/component/k2/item/278
Copyright: CHART32
Processing: Bernd Flach-Wilken

Click to view full size image

[starsurfer]

NGC 6935-7
https://pbase.com/strongmanmike2002/ngc_69356937_indus
Copyright: Michael Sidonio