1999AJ....118..558K

Query : 1999AJ....118..558K

1999AJ....118..558K - Astron. J., 118, 558-571 (1999/July-0)

K-band variability as a method to select young stellar object candidates.

KAAS A.A.

Abstract (from CDS):

A study of the applicability of K- (2.2 µm) band variability as a method to separate young stellar objects (YSOs) from field stars in young embedded clusters is presented. Deep K-band imaging of the central ∼ 8'x6' region of the Serpens Cloud Core was made at several epochs in 1995 and 1996. Variability in K was detectable at peak-to-peak amplitudes as small as typically ΔK=0.15 at a conservative 3 σ level for sources brighter than K~15. This level increases gradually to ΔK=1.3 at K~18. From a multi-epoch sample of about 1000 stars (K<18), a total of 55 stars have been found to exhibit variability in the K band at observed amplitudes from 0.15 to 2.2 mag, and nine of these have varied at several of the investigated epochs. Thirty-nine of the 55 variable sources were not previously recognized and are hereby proposed as new YSO candidates. Not less than 26% of the total sample of already known YSOs within this region were found to vary over a timescale of only 1 yr. We conclude that the K-variability method is efficient in finding low-luminosity young sources in deeply embedded clusters. In addition, deep J (1.25 µm) and H (1.65 µm) imaging of the same region revealed 37 near-IR excess sources from their position in the J-H/H-K diagram, and 17 of these are new. One additional YSO candidate was found from association with nebulosity. The total of 57 new YSO candidates increases the currently recognized YSO population by 85% within the observed field. The K luminosity function continues to rise down to K~16, and no turnover is found at K>16 that might not be due to sample incompleteness. The new sources are probably very low mass pre-main-sequence stars and young brown dwarfs.

Abstract Copyright: ∼

Journal keyword(s): Stars: Formation - Stars: Low-Mass, Brown Dwarfs - Stars: Luminosity Function, Mass Function - Stars: Variables: Other

Nomenclature: Table 1: [K99d] 1-NN (Nos 1-1 to 1-37). Table 2: [K99d] 2-N (Nos 2-1 to 2-7). Table 3: [K99d] 3-NN (Nos 3-1 to 3-14). Table 4: [K99d] 4-NN (Nos 4-1 to 4-45). Table 5: [K99d] YSO NN (Nos 1-57).

CDS comments: p. 562: FIRS = [HWJ84] FIRS 1.

Simbad objects: 106

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Number of rows : 106
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 [K99d] YSO 1 Y*O 18 29 46.1 +01 15 39           ~ 1 0
2 2MASS J18294641+0112217 Y*O 18 29 46.42 +01 12 21.7           ~ 2 0
3 [K99d] YSO 4 Y*O 18 29 46.5 +01 14 33           ~ 1 0
4 [K99d] YSO 3 Y*O 18 29 46.6 +01 12 07           ~ 1 0
5 [K99d] YSO 5 Y*O 18 29 47.2 +01 13 14           ~ 1 0
6 [K99d] YSO 6 Y*O 18 29 47.3 +01 16 01           ~ 1 0
7 [K99d] YSO 7 Y*O 18 29 48.2 +01 13 03           ~ 1 0
8 2MASS J18294878+0113422 Y*O 18 29 48.787 +01 13 42.22           ~ 12 0
9 [K99d] YSO 9 Y*O 18 29 49.0 +01 12 51           ~ 1 0
10 NAME Serpens Cloud SFR 18 29 49 +01 14.8           ~ 1100 2
11 IRAS 18272+0114 Or* 18 29 49.13016 +01 16 20.6472           ~ 76 1
12 V* V370 Ser Or* 18 29 49.24584 +01 16 31.5480           ~ 31 0
13 [EC92] 39 * 18 29 49.6 +01 14 45           ~ 2 0
14 GCNM 23 Y*O 18 29 49.63 +01 15 21.9           ~ 273 2
15 [K99d] YSO 10 Y*O 18 29 50.3 +01 12 41           ~ 1 0
16 [K99d] YSO 12 Y*O 18 29 50.5 +01 13 26           ~ 1 0
17 [K99d] YSO 11 Y*O 18 29 50.6 +01 12 14           ~ 1 0
18 2MASS J18295118+0113196 Y*O 18 29 51.186 +01 13 19.62           ~ 16 0
19 V* V371 Ser Or* 18 29 51.21240 +01 16 39.4860           ~ 119 1
20 [EC92] 54 * 18 29 51.5 +01 14 05           ~ 2 0
21 GCNM 40 Y*O 18 29 51.7 +01 13 14           ~ 2 0
22 [EC92] 55 * 18 29 51.7 +01 15 20           ~ 2 0
23 [K99d] YSO 14 Y*O 18 29 51.9 +01 14 42           ~ 1 0
24 [K99d] YSO 15 Y*O 18 29 51.9 +01 14 45           ~ 1 0
25 SSTc2d J182952.1+011322 Y*O 18 29 52.13 +01 13 21.9           ~ 5 0
26 GCNM 46 Y*O 18 29 52.2 +01 13 23           ~ 3 0
27 2MASS J18295229+0116184 Y*O 18 29 52.29 +01 16 18.4           ~ 3 0
28 GCNM 48 Y*O 18 29 52.6 +01 14 23           ~ 2 0
29 [K99d] YSO 20 Y*O 18 29 52.6 +01 14 45           ~ 1 0
30 GCNM 51 * 18 29 52.7 +01 13 26           ~ 3 0
31 2MASS J18295286+0113094 Y*O 18 29 52.861 +01 13 09.44           ~ 3 0
32 GCNM 52 Y*O 18 29 52.9 +01 14 36           ~ 2 0
33 2MASS J18295317+0112275 BD* 18 29 53.176 +01 12 27.55           L 16 0
34 GCNM 56 Y*O 18 29 53.2 +01 14 28           ~ 2 0
35 [K99d] YSO 24 Y*O 18 29 53.2 +01 14 38           ~ 1 0
36 GCNM 58 * 18 29 53.5 +01 14 04           ~ 2 0
37 2MASS J18295354+0113051 Y*O 18 29 53.5520163456 +01 13 05.177772516           ~ 9 0
38 [K99d] YSO 25 Y*O 18 29 54.0 +01 12 19           ~ 1 0
39 [K99d] YSO 26 Y*O 18 29 54.0 +01 14 07           ~ 1 0
40 GCNM 66 Y*O 18 29 54.1 +01 14 38           ~ 3 0
41 [K99d] YSO 30 Y*O 18 29 54.2 +01 16 36           ~ 1 0
42 [K99d] YSO 28 Y*O 18 29 54.3 +01 12 19           ~ 1 0
43 GCNM 68 Y*O 18 29 54.3 +01 14 45           ~ 3 0
44 2MASS J18295452+0114469 Y*O 18 29 54.5185217904 +01 14 46.974838092           M8.0 10 0
45 2MASS J18295520+0113222 Y*O 18 29 55.200 +01 13 22.21           ~ 17 0
46 2MASS J18295571+0114315 Y*O 18 29 55.711 +01 14 31.50           ~ 39 0
47 [K99d] YSO 31 Y*O 18 29 55.9 +01 11 29           ~ 1 0
48 2MASS J18295635+0112180 Y*O 18 29 56.3551125576 +01 12 18.078171192           M8.5 11 0
49 SSTc2d J182956.4+011333 * 18 29 56.38 +01 13 33.1           ~ 6 0
50 SSTc2d J182956.7+011321 V* 18 29 56.71 +01 13 20.6   16.62       ~ 6 1
51 GCNM 88 * 18 29 56.8 +01 15 45           ~ 3 0
52 HBC 672 Em* 18 29 56.8848005064 +01 14 46.304766672   17.6       K8.0 102 0
53 GCNM 89 * 18 29 57.0085337280 +01 16 08.577298668           ~ 4 0
54 2MASS J18295751+0113492 Y*O 18 29 57.510 +01 13 49.25           ~ 9 0
55 2MASS J18295760+0113004 Y*O 18 29 57.602 +01 13 00.42           ~ 36 3
56 IRAS 18274+0112 Y*O 18 29 57.73680 +01 14 05.6940           M4: 139 2
57 2MASS J18295781+0112280 Y*O 18 29 57.819 +01 12 28.05           ~ 21 0
58 GCNM 107 Y*O 18 29 58.1 +01 15 57           ~ 2 0
59 2MASS J18295820+0115216 Y*O 18 29 58.2037073472 +01 15 21.610474308           K7.0 40 0
60 [K99d] YSO 34 Y*O 18 29 58.3 +01 16 22           ~ 1 0
61 2MASS J18295876+0114257 Y*O 18 29 58.765 +01 14 25.78           ~ 25 1
62 GCNM 114 * 18 29 58.8 +01 13 04           ~ 5 0
63 [EC92] 101 * 18 29 58.8 +01 13 17           ~ 3 0
64 [EC92] 104 * 18 29 58.9 +01 15 03           ~ 3 0
65 2MASS J18295914+0114411 Y*O 18 29 59.146 +01 14 41.13           ~ 3 0
66 CK 8 TT* 18 29 59.2453548960 +01 14 07.611180936   19.7   16.9   K7.5 31 0
67 GCNM 120 * 18 29 59.3 +01 12 28           ~ 2 0
68 SSTc2d J182959.5+011159 cor 18 29 59.573 +01 11 58.39           ~ 25 0
69 2MASS J18300020+0114035 Y*O 18 30 00.206 +01 14 03.56           ~ 14 0
70 GCNM 132 Y*O 18 30 00.3 +01 14 45           ~ 3 0
71 CK 2 Y*O 18 30 00.618 +01 15 20.12           K5-M0III 52 0
72 [ACA2003] Ser A 7 cor 18 30 00.68 +01 13 01.2           ~ 18 1
73 GCNM 145 * 18 30 01.0 +01 15 50           ~ 2 0
74 2MASS J18300107+0116498 * 18 30 01.07 +01 16 49.9           ~ 4 0
75 2MASS J18300111+0113242 Y*O 18 30 01.110 +01 13 24.24           ~ 14 0
76 2MASS J18300153+0115150 Y*O 18 30 01.5335499336 +01 15 14.987965320           ~ 16 0
77 GCNM 150 * 18 30 02.0 +01 13 01           ~ 2 0
78 GCNM 151 * 18 30 02.0 +01 14 05           ~ 2 0
79 JCMTSF J183001.8+011509 * 18 30 02.0 +01 15 09           ~ 4 0
80 2MASS J18300209+0113587 Y*O 18 30 02.095 +01 13 58.79           ~ 22 0
81 [EC92] 126 * 18 30 02.1 +01 13 37           ~ 2 0
82 GCNM 157 * 18 30 02.5 +01 14 15           ~ 3 0
83 [EC92] 130 * 18 30 02.8 +01 13 18           ~ 2 0
84 [K99d] YSO 38 Y*O 18 30 03.6 +01 15 04           ~ 1 0
85 [EC92] 138 * 18 30 03.6864560496 +01 16 14.271874212           ~ 4 0
86 [K99d] YSO 39 Y*O 18 30 04.9 +01 12 12           ~ 1 0
87 2MASS J18300491+0114393 Y*O 18 30 04.9153250976 +01 14 39.341792832           M5.0 15 0
88 2MASS J18300502+0112360 Y*O 18 30 05.022 +01 12 36.07           M9.0 13 0
89 [K99d] YSO 42 Y*O 18 30 08.3 +01 11 39           ~ 1 0
90 [K99d] YSO 43 Y*O 18 30 08.8 +01 12 02           ~ 1 0
91 [K99d] YSO 44 Y*O 18 30 08.9 +01 15 47           ~ 1 0
92 [K99d] YSO 45 Y*O 18 30 09.3 +01 14 07           ~ 1 0
93 [K99d] YSO 46 Y*O 18 30 09.7 +01 15 21           ~ 1 0
94 [K99d] YSO 47 Y*O 18 30 10.6 +01 16 21           ~ 1 0
95 [K99d] YSO 49 Y*O 18 30 11.1 +01 12 57           ~ 1 0
96 [K99d] YSO 48 Y*O 18 30 11.2 +01 12 12           ~ 1 0
97 [K99d] YSO 50 Y*O 18 30 11.6 +01 13 57           ~ 1 0
98 2MASS J18301208+0116422 Y*O 18 30 12.0808843848 +01 16 42.177765756           ~ 5 0
99 [K99d] YSO 52 Y*O 18 30 12.3 +01 17 45           ~ 1 0
100 [K99d] YSO 53 Y*O 18 30 12.5 +01 15 33           ~ 1 0
101 [K99d] YSO 54 Y*O 18 30 13.3 +01 15 31           ~ 1 0
102 [K99d] 3-11 IR 18 30 13.3 +01 17 46           ~ 1 0
103 [K99d] YSO 55 Y*O 18 30 13.5 +01 12 18           ~ 1 0
104 [K99d] YSO 56 Y*O 18 30 15.4 +01 17 30           ~ 1 0
105 [K99d] YSO 57 Y*O 18 30 15.6 +01 17 31           ~ 1 0
106 NGC 7023 RNe 21 01 36.9 +68 09 48           ~ 702 0

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