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>> I have had another look at SIMBAD and find NSV4499 is listed but not under
>> that designation.
If you key-in either the name SV* HV 8200 _or_ NSV 4499, then the same
results page will turn up. Usually star names will appear in alphanumeric
order among the aliases, and presumably in this case it's the 'HV' that's
causing that name to be shown first rather than the NSV name. Again,
match stuff in SIMBAD by _position_, not by name, since many objects have
multiple names and/or multiple entries for the same star.
>> It appears as HV8200 = IRAS 09262-5159.
No! A little "catalogue astrophysics": since the source position
for the NSV star (Luyten's) is approximate, it might seem reasonable to
at least suspect an identification here, since the IRAS position is only
about 90" due south of the nominal place. _However_, if you look at
the fluxes shown for the four IRAS passbands (using the SIMBAD Web interface,
click on the "display" button under "Measurements"), you'll see that only
for the 25-micron band is there other than an upper limit detection.
Here's the IRAS data block for IRAS 09262-5159:
IRAS | ra, dec (1950) | err.ellip| f12 f25 f60 f100 |
%flux.err. |conf| v|ns|na| reference |
-------------------------------------------------------------------------------
IRAS |09 26 16.3 -51 59 22| 37 9 130| .25L .41 4.47L 14.51L|
~ 15 ~ ~|----| ~| 0| 1|1988NASAR1190....1B|
-------------------------------------------------------------------------------
The numbers falling under f12, f25, f60, f100 are the ones you want to look at.
The 'L' next to the numbers indicates an upper limit in brightness in that
band (i.e. no detection separate from the background). If the NSV star were a
red variable, then the situation would be that some flux would be present in
the 12-micron band, half (or less) the 12-micron value at 25-microns, and
usually nothing at the 60- and 100-micron bands.
The 12-micron flux in evolved red stars comes from silicate emission in
the outermost envelope of the star (way beyond the photosphere, in these cases
sometimes at 100 AU radius!), which peaks very broadly around 10-microns.
This is practically a defining characteristic of AGB stars in IRAS data.
If IRAS shows no 12-micron detection, then that IRAS source is a
"something else". Usually things peaking at 25- and 60-microns are either
planetary nebulae or ordinary HII regions; things peaking at either 60- or
100-microns are either HII regions or galaxies. The longer wavelength IRAS
"colors" are not very diagnostic except to say that the object is some sort
of nebula, where "nebula" can mean a cool shell around a hot star,
a planetary, a galactic nebula, or a galaxy. For IRAS 09262-5159, since
there is only a weak 25-micron detection, this is not a star---or at least
not an AGB star (Mira, semiregular, etc.).
Although Mati seems confident in the identification, real verification
of the blue star as the NSV object would have to be done on the Harvard
plate(s) that Luyten used. The hope would be that there is a pen mark on one
of the plates showing the intended star. The large range and fairly bright
blue magnitude reported by Luyten lead me to suspect the mag. 13 blue star is
not the intended variable.
Here's my hunch: NSV 4499 is actually Y Vel with a -1m RA error in
Luyten's NSV position. The (blue) magnitude and magnitude range is about
right, and a typo of this sort in the position either as determined or as
published is not uncommon. Just a hunch, so this needs to be looked at with
original source material at Harvard (hic labor, hic opus est --- and what would
you really learn?!)
\Brian (who will accept or buy the cappuccinos depending on
how his hunch works out)
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