Found images: 2017 January

[Ann]

vdB38 and Sh2-265
http://www.atacama-photographic-observa ... .php?id=61
Copyright: Thierry Demange, Richard Galli and Thomas Petit
vdb38.jpg

This is a really fascinating image!

The van den Bergh object in the image is the blue reflection nebula, which is mixed with and surrounding a bubble-shaped pink emission nebula. The star inside the nebula is HD 34989, a 6th magnitude B1V main sequence star. Despite being inside a nebula, which will scatter and dilute the blue light of the star, the light that reaches us from HD 34989 is still quite blue, with a Tycho B-V index of about −0.140.

Because HD 34989 is a B1V star it must be quite young, and it is possible that the nebula surrounding it might be a remnant of its natal cloud.

To me, the most fascinating aspect about HD 34989 is that it is indeed a B1V star, and still it is surrounded by an emission nebula. I think stars of spectral class B1 are at the borderline of where stars are hot enough to ionize a nebula, so seeing this star and its pink nebula is like watching one of the borderline phenomena in space, a place where hydrogen changes from one state of being into another.

Ann

[starsurfer]

NGC 4088 and NGC 4157
http://www.karelteuwen.be/photo_page.ph ... 9&album=14
Copyright: Karel Teuwen

NGC 4088 is the galaxy on the left and NGC 4157 is the galaxy on the right.

[starsurfer]

CG 30-1
http://www.astrostudio.at/1_Deep%20Sky% ... 86_CG3.jpg
Copyright: Gerald Rhemann

Click to view full size image

This group of cometary globules is located in the constellation Puppis.

[starsurfer]

IC 1340
http://www.astro-koop.de/?attachment_id=1653
Copyright: Stefan Heutz, Wolfgang Ries and Michael Breite

Click to view full size image

This is part of the Veil Nebula.

[bystander]

Signatures from the Past
ESO Picture of the Week | 2017 Jan 30

[img3="Credit: ESO/Babak Tafreshi (TWAN)"]https://cdn.eso.org/images/thumb700x/potw1705a.jpg[/img3][hr][/hr]

This picture shows the ESO 3.6-metre telescope, located at the La Silla Observatory in Chile. The night sky overhead is dominated by the Moon, which shines so brightly that illuminates the scene fully.

The most dominant feature of this image is the red rock in the foreground. It is marked with prehistoric engravings — signatures from the region’s past. Several such engravings can be found around La Silla, but this particular rock is part of the richest site in the area.

A complete photographic and topographic survey of these engravings was carried out in 1990. The carved rocks predominantly depict scenes involving men and animals, as well as mysterious geometrical figures. It is believed that these engravings originate from the El Molle complex — the first culture in the north of Chile. Geologists believe that the first millennium of our era experienced a lot more rainfall than it does today, allowing parts of the Atacama Desert to support various civilised cultures.

[bystander]

The Calabash Clash
ESA Hubble Picture of the Week | 2017 Jan 30

[img3="Credit: ESA/Hubble, NASA
Acknowledgement: Judy Schmidt"]https://cdn.spacetelescope.org/archives ... w1705a.jpg[/img3][hr][/hr]

The Calabash Nebula, pictured here — which has the technical name OH 231.8+04.2 — is a spectacular example of the death of a low-mass star like the Sun. This image taken by the NASA/ESA Hubble Space Telescope shows the star going through a rapid transformation from a red giant to a planetary nebula, during which it blows its outer layers of gas and dust out into the surrounding space. The recently ejected material is spat out in opposite directions with immense speed — the gas shown in yellow is moving close to a million kilometres an hour.

Astronomers rarely capture a star in this phase of its evolution because it occurs within the blink of an eye — in astronomical terms. Over the next thousand years the nebula is expected to evolve into a fully fledged planetary nebula.

The nebula is also known as the Rotten Egg Nebula because it contains a lot of sulphur, an element that, when combined with other elements, smells like a rotten egg — but luckily, it resides over 5000 light-years away in the constellation of Puppis (The Poop deck).

[Ann]

The Calabash Clash
ESA Hubble Picture of the Week | 2017 Jan 30

[img3="Credit: ESA/Hubble, NASA
Acknowledgement: Judy Schmidt"]https://cdn.spacetelescope.org/archives ... w1705a.jpg[/img3][hr][/hr]

The Calabash Nebula, pictured here — which has the technical name OH 231.8+04.2 — is a spectacular example of the death of a low-mass star like the Sun.

I must protest against the use of the term "a low-mass star like the Sun".

Eckhart Spalding of astrobites.org wrote about star formation in the Orion Nebula:
Surprisingly, the mass function corresponding to an age of 2-5 million years has two distinct peaks (Fig. 2)! If the Orion Nebula is indeed that old (some think it might actually be younger) and if the isochrones are accurate (isochrones are debatable at the lowest masses), then the Orion Nebular Cloud seems to be preferentially producing objects at around 0.25 and 0.025 solar masses. These correspond to low-mass stars and brown dwarfs.

According to Eckhart Spalding's research, the Orion Nebula might preferentially produce stars as lightweight one fourth the mass of the Sun, corresponding to very faint M-type dwarfs. In any case, our galaxy is teeming with low-mass M-type dwarfs, which contain considerably less mass and are many times more common than G-type stars like the Sun.

Compared to what most stars in our galaxy are like, the Sun is massive!

Ann