Colors Of Astronomical Objects And Extinction
Expected Detection Limits For Astronomical Objects
Extinction
A_J = 0.274 A_V
A_H = 0.165 A_V
A_K = 0.10 A_V
J-K (due to extinction) = 0.174 * A_V
J-H (due to extinction) = 0.110 * A_V
H-K (due to extinction) = 0.065 * A_V
Stars
Dwarfs
IR from Bessell, M.S., and Brett, J.M. 1988 PASP 100,1134
Vis. from Allen, C.W., Astrophysical Quantities, 1973 (London: Athlone)
Sp. Mv Mk V-K J-H H-K J-K
A0 0.7 -0.7 0.00 0.00 0.00 0.00
F0 2.6 1.9 0.70 0.13 0.03 0.16
G0 4.4 3.0 1.41 0.305 0.05 0.36
K0 5.9 3.9 1.96 0.45 0.075 0.53
M0 9.0 5.4 3.65 0.695 0.165 0.86
M5 11.8 5.7 6.12 0.62 0.32 0.94
Giants
(same refs. as dwarfs)
G0 1.1 -0.7 1.75 0.37 0.065 0.45
K0 0.5 -1.8 2.31 0.54 0.095 0.65
M0 -0.4 -4.3 3.85 0.83 0.19 1.01
M5 0.8 -6.8 5.96 0.95 0.285 1.23
Supergiants:
from Lee 1970, Ap.J. 162, 217.
Sp. J-H H-K
M0 0.80 0.19
M1 0.81 0.19
M2 0.83 0.23
M3 0.90 0.26
M4 0.94 0.26
M5 1.0 0.3
M0 Mv=-5 (Allen 1973) => Mk=-8.82
Late M dwarfs ("old disk")
from Bessell, M.S. 1991, Ap.J. 101, 662
Sp. Mv Mk J-H H-K
K7 8.23 5.03 0.66 0.15
M0 8.86 5.22 0.67 0.17
M1 9.41 5.55 0.66 0.18
M2 10.16 6.02 0.66 0.20
M3 11.18 6.53 0.64 0.23
M4 12.71 7.44 0.62 0.265
M5 14.69 8.52 0.62 0.33
M5.5 15.75 9.04 0.64 0.35
M6 16.63 9.26 0.66 0.38
M6.5 17.70 9.60 0.70 0.42
M7 18.60 10.05 0.75 0.47
M7.5 19.5: 10.6: 0.80 0.51
Long Period Variables:
from Wood & Bessell 1983, Ap.J. 265, 748.
P * *
100 -6.35 1.15 0.35 0.8
200 -7.00 1.15 0.35 0.8
250 -7.33 1.28 0.39 0.89
300 -7.65 1.41 0.51 0.93
350 -7.98 1.54 0.56 0.98
400 -8.30 1.67 0.63 1.04
450 -8.63 1.80 0.71 1.09
notes: Galactic bulge Miras; R=9 kpc; dMk~0.8m; d(J-K)~0.7m.
*estimated from graph
Classical Cepheid Variables:
from Hindsley, R.B., and Bell, R.A. 1990, ApJ 348, 673
P
1 -1.53 -2.42 0.17 0.02
10 -4.64 -6.30 0.28 0.07
20 -5.58 -7.46 0.32 0.09
40 -6.51 -8.63 0.35 0.10
60 -7.06 -9.32 0.37 0.11
80 -7.45 -9.80 0.38 0.12
100 -7.75 -10.18 0.39 0.12
135 -8.16 -10.68 0.41 0.13
Impey et al 1986 (Ap.J. 309:572) give the reddening and K-corrected colors of 47 optically-selected bright elliptical galaxies observed with a small (5.8 - 7.5") beam, which represents values of log A/D(0) of -2 to -1 for these galaxies.
mean J-H = 0.75 +- 0.04 mag (sigma pop)
mean H-K = 0.20 +- 0.04 mag
Frogel et al 1985 give the reddening and K-corrected colors of 19 Sc galaxies observed with a 6.6" aperture which also represents values of log A/D(0) of -2 to -1 for these galaxies.
mean J-H = 0.70 +- 0.07 mag (sigma pop)
mean H-K = 0.25 +- 0.06 mag
The Sc galaxies have highly correlated J-H and H-K colors. See plot of all measurements for both galaxy types.
The scatter plot for the ellipticals intersects the giant star curve at M1, but the scatter is preferentially almost perpendicular to it.
Aaronson, Huchra and Mould have unpublished data of tbs galaxies. Their JHK observations have much larger apertures which are similar in size to the 2mass effective apertures. About 90 of those galaxies have been used so far to check two important effects:
The K-correction is the change of magnitude with redshift due to flux shifting to longer wavelengths.
usage: K(0) = K(z) + coefficient * redshift
K Correction for elliptical galaxies:
| Band or Color | Coefficient |
|---|---|
| J | -0.7 |
| H | -0.2 |
| K | 3.3 |
| L' | 3.5 |
| J-H | -0.5 |
| H-K | -3.5 |
L* Galaxy to z=0.1. M stars type M_K detection limit (kpc) photometric limit (kpc) M Supergiant -11.5 1250 800 carbon star -8 250 150 Mira variable -8 250 150 M Giant -7 150 100 Pop II K giant -6 100 60 dwarf M stars: Spectral type distance(pc) M0 630 M1 582 M2 457 M3 354 M4 234 M5 144 M5.5 112 M6 102 M6.5 87 M7 70 M7.5 54 Maximum number of Brown dwarfs (if total mass density = 0.1 solar masses/pc^3): Mass (solar masses) Age(Gyr) Distance(pc) Number 0.08 1 2000 0.08 5 200 0.08 10 30 0.04 1 300 0.04 5 10 0.04 10 0.1 0.02 1 3 0.02 4 0.01Number of asteroids
