Access to Astronomical Catalogues

← Click to display the menu
J/AJ/126/2421       2MASS-Selected sample of ultracool dwarfs    (Cruz+, 2003)

Meeting the cool neighbors. V. A 2MASS-Selected sample of ultracool dwarfs. Cruz K.L., Reid I.N., Liebert J., Kirkpatrick J.D., Lowrance P.J. <Astron. J., 126, 2421-2448 (2003)> =2003AJ....126.2421C
ADC_Keywords: Stars, dwarfs ; Infrared sources ; Photometry, infrared ; Stars, late-type ; Stars, distances Keywords: Galaxy: stellar content - solar neighborhood - stars: low-mass, brown dwarfs - stars: luminosity function, mass function Abstract: We present the initial results of our effort to create a statistically robust, volume-limited sample of ultracool dwarfs from the Two Micron All Sky Survey Second Incremental Data Release (II/241). We are engaged in a multifaceted search for nearby late-type objects, and this is the first installment of our search using purely photometric selection. The goal of this work is a determination of the low-mass star and brown dwarf luminosity function in the infrared. Here we outline the construction of the sample, dubbed 2MU2, and present our first results, including the discovery of 186 M7-L6 dwarfs, 47 of which are likely to be within 20pc of the Sun. These results represent 66% of the ultracool candidates in our sample yet constitute a 127% increase in the number of ultracool dwarfs known within the volume searched (covering 40% of the sky out to 20pc). In addition, we have identified 10 M4-M6.5 objects that are likely to be within 20pc (or within 1σ). Finally, based on these initial data, we present a preliminary luminosity function and discuss several interesting features of the partial sample presented here. Once our sample is complete, we will use our measured luminosity function to constrain the mass function of low-mass stars and brown dwarfs. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 134 112 Previously known cool dwarfs recovered in the 2MU2 sample refs.dat 80 51 References table7.dat 132 47 M7-L8 Dwarfs Discovered within 20pc table8.dat 132 139 M7-L8 Dwarfs Discovered outside 20pc table9.dat 132 10 Early-Type M Dwarfs Discovered within 20pc table10.dat 132 53 Early-Type M dwarfs Discovered outside 20pc notes.dat 80 22 Notes of tables 7, 8, 9 and 10 table11.dat 96 5 Young objects table12.dat 96 34 Spectroscopically confirmed giants table13.dat 106 16 Spectroscopically confirmed carbon stars table14.dat 44 56 JMAG/Spectral type calibration data table15.dat 75 117 The J<9 Sources with IRAS Catalog Counterpart table16.dat 73 138 The J<9 Sources with Stellar Counterparts table17.dat 73 13 Carbon Stars table18.dat 73 80 Miras and Long-Period Variables table19.dat 73 16 Semiregular Variables
See also: II/241 : 2MASS Catalog Intermediate Data Release (IPAC/UMass, 2000) J/AJ/123/2806 : Nearby stars in the NLTT catalogue (Reid+, 2002) J/AJ/123/2822 : Photometry of southern NLTT stars (Reid+, 2002) J/AJ/123/2828 : Spectroscopy of northern NLTT stars (Cruz+, 2002) J/AJ/126/2449 : Nearby ultracool dwarfs in galactic plane (Reid+, 2003) J/AJ/126/3007 : Spectroscopy of faint red NLTT dwarfs (Reid+, 2003) J/AJ/128/463 : A preliminary 20pc census from the NLTT cat. (Reid+, 2004) J/AJ/130/1680 : LSPM-North proper-motion catalog nearby stars (Lepine+, 2005) Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 14 A14 --- 2MASSI 2MASSI Designation 15- 16 A2 --- f_2MASSI [* ] star included in preliminary LF (1) 18- 46 A29 --- OName Other Names 48- 53 F6.3 mag Jmag J magnitude 54 A1 --- n_Jmag [a] Note on Jmag (2) 56- 60 F5.3 mag J-H J-H colour index 62- 66 F5.3 mag J-Ks J-Ks colour index 68- 72 A5 --- SpType Spectral type 73 A1 --- n_SpType [cd] Note on SpType (2) 75- 78 F4.1 mag JMAG ? Estimated absolute J magnitude 80- 82 F3.1 mag e_JMAG ? rms uncertainty on JMAG 83 A1 --- u_JMAG [)] ): estimate based on the system's combined spectral type and photometry 85- 88 F4.1 pc Dist ? Estimated distance 90- 92 F3.1 pc e_Dist ? rms uncertainty on Dist 93 A1 --- u_Dist [)] ): estimate based on the system's combined spectral type and photometry 94 A1 --- n_Dist [fhijkm] Note on JMAG and Dist (2) 96-100 F5.2 mag JpiMAG ? Absolute J magnitude based on trigonometric parallax data 102-105 F4.2 mag e_JpiMAG ? rms uncertainty on JpiMAG 106 A1 --- f_JpiMAG [bge] Note on JpiMAG (2) 108-112 F5.2 pc Distpi ? Distance based on trigonometric parallax data 114-117 F4.2 pc e_Distpi ? rms uncertainty on Distpi 119-120 A2 --- r_Distpi Trigonometric Parallax references, in refs.dat file 122-130 A9 --- r_Mult Multiplicity references, in refs.dat file 132-134 A3 --- r_Disc Discovery references, in refs.dat file
Note (1): Objects included in our preliminary luminosity function (Spectral type≥M7 and d≤20 pc) are marked with one asterisk; binaries are marked with two asterisks. Note (2): Notes: a: Photometry listed is from Dahn et al., 2002AJ....124.1170D as the 2MASS photometry is contaminated by a meteor. b: JMAG=13.85 for both components. c: SpType changed from M8 in Gizis et al., 2000AJ....120.1085 d: SpType changed from M6 in PMSU (Reid et al., 2002AJ....124.2721R) e: JMAG=11.80 and 12.40 (Close et al., 2003ApJ...587..407C). f: JMAG=11.16 and 12.01 (Close et al., 2003ApJ...587..407C); d=21.8pc g: JMAG=11.09 and 14.92 (Freed, Close, & Siegler 2003ApJ...584..453F) h: JMAG=13.55 and 13.95 (Bouy et al., 2003, Cat. J/AJ/126/1526); d=21.8pc i: JMAG=11.32 and 12.10 (Close et al., 2003ApJ...587..407C). d=24.9pc j: Based on photometric distance found by Tinney, Mould, & Reid, 1993AJ....105.1045T k: JMAG=14.45 and 15.10 (Bouy et al., 2003, Cat. J/AJ/126/1526); d=25.4pc l: SpType changed from M5.5 in PMSU (Reid et al. 2002AJ....124.2721R) m: JMAG=11.16 and 11.33 (Close et al., 2003ApJ...587..407C); d=24.4pc
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 3 A3 --- Ref Reference code 5- 23 A19 --- BibCode BibCode 25- 46 A22 --- Aut Author's name 48- 80 A33 --- Com Comments
Byte-by-byte Description of file: table[789].dat table10.dat
Bytes Format Units Label Explanations
1- 6 A6 --- --- [2MASSI] 8- 21 A14 --- 2MASSI The 2MASS designation 23- 51 A29 --- OName Other name 53- 58 F6.3 mag Jmag The 2MASS J-band magnitude 60- 64 F5.3 mag J-H The 2MASS (J-H) color 66- 70 F5.3 mag J-Ks The 2MASS (J-Ks) color 72- 81 A10 "YYYY/MM/DD" Date Date of spectroscopic observation 83- 89 A7 --- TCode Telescope used for spectroscopic observation (G1) 91- 94 A4 --- SpType Spectral type 96 A1 --- n_SpType Note on SpType, in notes.dat file 97 A1 --- u_SpType [?] Uncertainty flag on SpType (2) 99-102 F4.1 mag JMAG Absolute J-band magnitude (3) 104-106 F3.1 mag e_JMAG ? Error in JMAG 108 A1 --- n_JMAG Note on JMAG, in notes.dat file 109-113 F5.1 pc Dist Distance (3) 115-118 F4.1 pc e_Dist ? Error in Dist 120 A1 --- n_Dist Note on Dist detailed in notes.dat file 122-132 A11 --- r_2MASSI Other references, in refs.dat file
Note (2): A "?" indicates that the uncertainty is either 1 or 2 types. For objects without a "?," the uncertainty is 0.5 types. Note (3): Estimates obtained using our calibration. In table7.dat, data for multiple systems are based on the system's combined spectral type and photometry.
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1 A1 --- Note Note code 3- 80 A78 --- Text Text of the note
Byte-by-byte Description of file: table11.dat table12.dat
Bytes Format Units Label Explanations
1- 14 A14 --- 2MASSI The 2MASSI designation 16- 21 F6.3 mag Jmag The 2MASS J-band magnitude 23- 27 F5.3 mag J-H The 2MASS (J-H) color 29- 33 F5.3 mag J-Ks The 2MASS (J-Ks) color 35- 44 A10 "YYYY/MM/DD" Date Date of spectroscopic observation 46- 52 A7 --- TCode Telescope used for spectroscopic observation (G1) 54- 63 A10 --- SpType Spectral type 65- 96 A32 --- Com Comments
Byte-by-byte Description of file: table13.dat
Bytes Format Units Label Explanations
1- 14 A14 --- 2MASSI The 2MASSI designation 16- 21 F6.3 mag Jmag The 2MASS J-band magnitude 23- 27 F5.3 mag J-H The 2MASS (J-H) color 29- 33 F5.3 mag J-Ks The 2MASS (J-Ks) color 35- 44 A10 "YYYY/MM/DD" Date Date of spectroscopic observation 46- 52 A7 --- TCode Telescope used for spectroscopic observation (G1) 54- 56 A3 --- VisPM [Yes No] Visual proper motion (2) 58 A1 --- --- [(] 59- 75 A17 --- Epoch Epoch 76 A1 --- --- [)] 78-104 A27 --- Com Comments (3) 106 A1 --- Note [b] Note (4)
Note (2): Possible visual proper motion determined by P.J. Lowrance from examining DSS, XDSS, and 2MASS images. Note (3): Epochs listed are either DSS-2MASS or XDSS R-2MASS. Note (4): A discussion of these new carbon dwarfs will appear in Lowrance et al. (2003, in prep.)
Byte-by-byte Description of file: table14.dat
Bytes Format Units Label Explanations
1- 23 A23 --- Name Name 25- 28 F4.1 --- SpType Spectral type (M5 = 5, L0 = 10, L8 = 18) 33- 37 F5.2 mag JMAG Absolute J magnitude 39- 42 F4.2 mag e_JMAG rms uncertainty on JMAG 44 I1 --- Ref Reference (1)
Note (1): References: (1) The 8pc sample; (2) Dahn et al., 2002AJ....124.1170D (3) PMSU, Reid et al., 2002AJ....124.2721R
Byte-by-byte Description of file: table1[5-9].dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Hour of right ascension (J2000) 4- 5 I2 min RAm Minute of right ascension (J2000) 7- 10 F4.1 s RAs Second of right ascension (J2000) 12 A1 --- DE- Sign of the declination (J2000) 13- 14 I2 deg DEd Degree of declination (J2000) 16- 17 I2 arcmin DEm Arcminute of declination (J2000) 19- 20 I2 arcsec DEs Arcsecond of declination (J2000) 22- 26 F5.2 mag Vmag ? The V-band magnitude 28- 32 F5.3 mag J-H ? The 2MASS (J-H) color 34- 38 F5.3 mag H-Ks ? The 2MASS (H-Ks) color 40- 44 F5.3 mag Ksmag ? The 2MASS Ks band magnitude 46- 50 F5.3 mag J-Ks ? The 2MASS (J-Ks) color 52- 73 A22 --- ID Other identifications
Global notes: Note (G1): Telescopes: KT = Kitt Peak; CT = Cerro Tololo.
History: From electronic version of the journal References: Reid & Cruz, Paper I 2002AJ....123.2806R, Cat. J/AJ/123/2806 Reid et al., Paper II 2002AJ....123.2822R, Cat. J/AJ/123/2822 Cruz & Reid, Paper III 2002AJ....123.2828C, Cat. J/AJ/123/2828 Reid et al., Paper IV 2003AJ....125..354R Reid, Paper VI 2003AJ....126.2449R, Cat. J/AJ/126/2449 Reid et al., Paper VII 2003AJ....126.3007R, Cat. J/AJ/126/3007 Reid et al., Paper VIII 2004AJ....128..463R, Cat. J/AJ/128/463
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 12-Jan-2004
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

catalogue service

© UDS/CNRS

Contact