2008A&A...488..181C


Query : 2008A&A...488..181C

2008A&A...488..181C - Astronomy and Astrophysics, volume 488, 181-190 (2008/9-2)

Contamination by field late-M, L, and T dwarfs in deep surveys.

CABALLERO J.A., BURGASSER A.J. and KLEMENT R.

Abstract (from CDS):

Deep photometric surveys of substellar objects in young clusters and high-redshift quasars are affected by contaminant sources at different heliocentric distances. If not correctly taken into account, the contamination may have a strong effect on the Initial Mass Function determination and on the identification of quasars. We calculate in detail the back- and foreground contamination by field dwarfs of very late spectral types (intermediate and late M, L, and T) in deep surveys and provide the data and tools for the computation. We adopt the latest models and data from the literature, which include the following: (i) a model of the Galactic thin disc by an exponential law; (ii) the length and height scales of late-type dwarfs; and (iii) the local spatial densities, absolute magnitudes, and colours of dwarfs for each spectral type. We derive a simplified expression for the spatial density in the thin disc that depends on the heliocentric distance and the galactic coordinates (l, b) and integrate this into the truncated cone studied in the survey. As a practical application, we compute the numbers of L- and T-type field dwarfs in very deep (I=21-29mag) surveys in the direction of the young σ Orionis cluster. The increasing number of contaminants at the faintest magnitudes could inhibit the study of the opacity mass limit at M≲0.003M in the cluster.

Abstract Copyright:

Journal keyword(s): stars: low-mass, brown dwarfs - stars: luminosity function, mass function - Galaxy: stellar content - Galaxy: open clusters and associations: individual: σ Orionis - methods: analytical

Simbad objects: 25

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Number of rows : 25
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME Hubble Ultra Deep Field reg 03 32 39.0 -27 47 29           ~ 1535 0
2 Cl Melotte 22 OpC 03 46 24 +24 06.8           ~ 3281 0
3 Cl Melotte 25 OpC 04 29 47 +16 56.9           ~ 2928 0
4 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2209 1
5 [BZR99] S Ori 55 LM* 05 37 25.88208 -02 34 32.0736         21.07 M9Ve 22 0
6 [BZR99] S Ori 70 BD* 05 38 10.10 -02 36 26.0           T6-7 46 0
7 [BZR99] S Ori 47 BD* 05 38 14.62416 -02 40 15.4020         20.53 L1e 28 0
8 [BZR99] S Ori 65 BD* 05 38 26.1 -02 23 05         23.23 L3.5: 10 0
9 NAME Garrison 1 OpC 05 38 42 -02 36.0           ~ 538 0
10 UGCS J053900.29-023705.7 Y*? 05 39 00.29712 -02 37 05.7648           M8 23 0
11 [BMZ2001] S Ori J053918.1-022855 Y*? 05 39 18.1 -02 28 55         23.89 ~ 11 0
12 [BZR99] S Ori 60 BD* 05 39 37.51848 -02 30 41.9220         22.75 L2 18 0
13 NGC 2632 OpC 08 40 13 +19 37.3           ~ 1449 0
14 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1095 1
15 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 760 0
16 NTTDF J1205-0744 BD* 12 05 20.21 -07 44 01.0           T7 12 1
17 NAME NGP reg 12 51 26.275 +27 07 41.70           ~ 1132 0
18 ULAS J145243.59+065542.9 BD* 14 52 43.57968 +06 55 42.9168           T4.5 5 0
19 Lupus 1 Cld 15 43 02.1 -34 09 06           ~ 264 0
20 NAME Lupus Complex SFR 16 03 -38.1           ~ 643 0
21 NAME Upper Sco Association As* 16 12 -23.4           ~ 1254 1
22 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3446 1
23 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13449 0
24 ULAS J223955.76+003252.6 BD* 22 39 55.75896 +00 32 52.6524           T5.5 8 0
25 HD 221356 PM* 23 31 31.5027738192 -04 05 14.650543968   7.03 6.49     F7V 156 0

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2023.02.02-19:48:12

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