Starship Asterisk*

Hannah's Dad wrote:Approximately how many foreground milky way stars are present in the image? How can one distinguish smaller sources in the Milky Way foreground from larger sources that may be in Andromeda?

TheSpam wrote:
Question: There is a rather large round source of light on the Ultraviolet image seen clearly just slightly below middle on the far left.
It appears much smaller in the optical light image (1/4 size roughly).

TheSpam wrote:
Any explanation for this? Larger/Brighter in Ultraviolet than in optical, what would that suggest?

owlice wrote:Art, the video was great; thanks for posting it!

neufer wrote: I'm ordering pepperoni, mushrooms, and dwarf galaxies on my next pizza. (MMMMMMM....)

biddie67 wrote:I'd love to have a series of posters to hang on the wall that showed Andromeda as seen in all the different wavelengths - they would make a fine display.

TheSpam wrote:Question: There is a rather large round source of light on the Ultraviolet image seen clearly just slightly below middle on the far left. It appears much smaller in the optical light image (1/4 size roughly).

Any explanation for this? Larger/Brighter in Ultraviolet than in optical, what would that suggest?

If your having trouble finding it quickly mouse over the two images repeatedly, it should become apparent fairly quickly.

orin stepanek wrote:http://astrophysics.gsfc.nasa.gov/outre ... new-light/
I get a not available on this server from this url!

Ann wrote: I believe that the red star in this picture is the same as the blue star in the GALEX image. But how can a star that is very red visually be very blue in ultraviolet light? Is that even possible?

Apparently so. The star in question would be EG Andromedae, a cool red M giant. EG Andromedae is very far away, possibly as much as 2,000 light-years, and it may be around 500 times as bright as the Sun in visual light. That, of course, means that it would be even brighter in infrared light, given the fact that this star is so cool. Its color index is 1.613 ± 0.014, which is a lot.

So EG Andromeda is a visually very red and cool star. But it is also a massive star, and its core is blazingly hot. Even though EG Andromedae is visually a red star, its core emits a lot of far ultraviolet light, and the star will show up as strikingly blue in a GALEX image.

• http://www.youtube.com/watch?v=1Dk83DYRgp0
  
  There once was an M giant in Andromeda
  Who watched little boys as they played with their
  Marbles and toys as in days of old yore
  And for a companion he had a white dwarf.

http://iopscience.iop.org/1538-3881/128/4/1790/204122.text.html wrote:
SYNTHETIC SPECTRAL ANALYSIS OF THE HOT COMPONENT IN THE S-TYPE SYMBIOTIC VARIABLE EG ANDROMEDAE
KELLY KOLB, JOLEEN MILLER, AND EDWARD M. SION
Department of Astronomy and Astrophysics, Villanova University.

AND JOANNA MIKOłAJEWSKA
Centrum Astronomiczne im. Mikołaja Kopernika, Polska Akademia Nauk, ulica Bartycka 18, PL-00-716 Warszawa, Poland.

Received 2004 March 29; accepted 2004 June 25

ABSTRACT

We have applied grids of non-LTE (NLTE) high-gravity model atmospheres and optically thick accretion disk models for the first time to archival IUE and FUSE spectra of the S-type symbiotic variable EG Andromedae taken at superior spectroscopic conjunction, when Rayleigh scattering should be minimal and the hot component is viewed in front of the red giant. For EG And's widely accepted, published hot-component mass, orbital inclination, and distance from the Hipparcos parallax, we find that hot, high-gravity, NLTE photosphere model fits to the IUE spectra yield distances from the best-fitting models that agree with the Hipparcos parallax distance, but at temperatures substantially lower than the modified Zanstra temperatures. NLTE fits to an archival FUSE spectrum taken at the same orbital phase as the IUE spectra yield the same temperature as the IUE temperature (50,000 K). However, for the same hot-component mass, inclination, and parallax-derived distance, accretion disk models at moderately high inclinations, ∼60°–75°, with accretion rates from 1 × 10-8 to 1 × 10-9 M⊙ yr-1 for white dwarf masses Mwd = 0.4 M⊙ yield distances grossly smaller than the distance from the Hipparcos parallax. Therefore, we rule out an accretion disk as the dominant source of the far-UV flux. Our findings support a hot bare white dwarf as the dominant source of far-UV flux.

Its core is blazingly hot? You can see the core??