J/ApJS/101/117 UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995)
Pre-main-sequence evolution in the Taurus-Auriga molecular cloud
Kenyon S.J., Hartmann L.
<Astrophys. J. Suppl. Ser. 101, 117 (1995)>
=1995ApJS..101..117K 1995ApJS..101..117K
ADC_Keywords: Stars, pre-main sequence ; Photometry
Keywords: infrared: stars - ISM: clouds - stars: evolution -
stars: luminosity function, mass function - stars: pre-main-sequence
Abstract:
This paper analyzes optical and infrared photometry of pre-main-
sequence stars in the Taurus-Auriga molecular cloud. More than half of
the stars in our sample have excess near-infrared emission. The
near-infrared excesses correlate very well with other measures of
activity, such as Halpha emission, ultraviolet excess emission,
millimeter continuum emission, and the presence of reflection nebulae
and molecular outflows. The infrared colors and the ratio of
far-infrared to bolometric luminosity display a smooth progression
from the most deeply embedded protostars to optically visible T Tauri
stars. Infalling envelope models account for the colors of protostars;
simple disk models similarly reproduce the colors of many T Tauri
stars.
Both the stellar birth line and a 10^5yr isochrone provide a
reasonable upper envelope to the luminosity distribution of optically
visible stars in the H-R diagram. Only a few stars in the cloud have
apparent ages exceeding 2-3x10^6yr, as derived from detailed
stellar evolution calculations. The distribution of stars in the H-R
diagram indicates that the cloud has formed stars at a roughly
constant rate for the past 1-2x10^6yr. Analyses of the J- and
K-luminosity functions support this conclusion. Within the
uncertainties, the observed mass distribution for optically visible
stars agrees with a Miller-Scalo initial mass function. Source
statistics imply a lifetime of 1-2x10^5yr for the typical protostar
in Taurus-Auriga. There is no evidence, however, that these sources
lie on the stellar birth line. Indeed, the protostellar luminosity
function is essentially identical to the luminosity function derived
for optically visible T Tauri stars in the cloud.
These results provide some support for the evolutionary sequence --
embedded protostar -> T Tauri star with a circumstellar disk -> T
Tauri star without a circumstellar disk -- currently envisioned in
standard models of low-mass star formation. Source statistics and
infrared color-color diagrams demonstrate that pre-main-sequence stars
develop bluer colors and display less evidence for circumstellar
material with time. The data show little evidence, however, for the
luminosity evolution expected along the proposed evolutionary
sequence. Time-dependent accretion during the infall phase may account
for the low luminosity of Taurus-Auriga protostars; this hypothesis
requires more tests.
Description:
Tables A1-A2 list average V and K magnitudes and broadband optical and
near-infrared colors for T Tauri stars in the Taurus-Auriga cloud. The
quoted errors are 1 sigma dispersions from the average values for
objects with 2 or more measurements at V, K, or the appropriate color.
For convenience, the authors quote dispersions of 0.00 for objects
with only a single measurement. The last columns of Tables A1-A2 list
the number of V, K, and N measurements used to compute the average
values. The number of data points used to determine average colors is
usually close to the number of V or K measurements.
Table A3 lists IRAS colors for the Taurus-Auriga sample. For each IRAS
source, the authors compiled fluxes from version 2 of the Point Source
Catalog, IRAS ADDSCANs, and the IRAS Serendipitous Survey Catalog and
averaged fluxes for sources appearing in 2 or 3 catalogs
(see section 2 of the printed paper). The authors adopted flux zero
points of Fnu(12um)=28.3Jy, Fnu(25um)=6.73Jy, Fnu(60um)=1.19Jy,
and Fnu(100um)=0.43Jy to compute IRAS magnitudes and then derived
colors using average K magnitudes from Table A2. In some cases, two or
more pre-main-sequence stars fall in a typical IRAS beam. The authors
summed the K flux of the individual objects to compute a combined K
magnitude and color for these IRAS sources. These IRAS colors assume
no color correction for the IRAS flux.
Table A4 lists various quantities derived from published spectra and
the photometry in Tables A1-A3. Infrared colors and the ratio of
far-IR to bolometric luminosity set the spectral energy distribution
class, SED. The optical spectral type usually was taken from the
literature (Herbig & Bell (1988LicOB1111....1H 1988LicOB1111....1H)) or the authors own
work. The effective temperature, Teff, is based on compilations by
Schmidt-Kaler (1982) and Straizys (1992). The authors
estimated optical extinctions, A_V, from comparisons between the
observed optical or infrared colors and colors for normal main
sequence stars in Table A5. The authors adopted Bessell & Brett's
(1988PASP..100.1134B 1988PASP..100.1134B) extinction curve to derive A_V from the optical
color excess and to derive the extinction at 1.25um, A_J. The stellar
luminosity, L_J, follows from the observed J magnitude, the
extinction, and an appropriate bolometric correction from Table A5 for
a distance of d=140pc. The 7-135um luminosity, L_FIR, and the
bolometric luminosity, L_b, are both integrations over the
reddening-corrected flux distribution. The 7-135um luminosity is
quoted as an upper limit for sources not detected by IRAS. Lower
limits on L_b are quoted for sources with incomplete photometry.
Table A5 lists adopted broadband colors for main sequence stars. For
the optical colors, this list is based on data compiled by
Johnson (1966, ARA&A, 4, 193; U-B, B-V, V-R_J, and V-J_C),
Schmidt-Kaler ((1982) ; U-B and B-V), and Bessell
((1990A&AS...83..357B 1990A&AS...83..357B) and 1990, PASP, 102, 1181; U-B, B-V, V-R_C, and
V-I_C). Bessell & Brett (1988PASP..100.1134B 1988PASP..100.1134B) contains the most
comprehensive list of main sequence IR colors. The authors
supplemented their Table II with colors from Johnson (1966, ARA&A, 4,
193) for early-type main sequence stars. Johnson (1966, ARA&A, 4, 193)
contains the best list of K-N colors for main sequence stars. To
complement these data, the authors compiled V-[12] colors using stars
selected from the Third Catalog of Nearby Stars (Gliese & Jahreiss
1979A&AS...38..423G 1979A&AS...38..423G). The authors extracted 12um fluxes from version 2
of the IRAS Point Source Catalog, color-corrected the fluxes assuming
a color temperature equal to the stellar effective temperature, and
computed a V-[12] color assuming a 12um zero point of 28.3Jy. The
tabulated color is the median color. The tabulated visual bolometric
corrections, BCV=Mbol-M_V, were used to derive absolute J
luminosities, L_J. The authors adopted BC_V from Schmidt-Kaler (1982;
also Straizys 1992) for stars with spectral types earlier than K6; the
authors integrated the energy distribution over wavelength to derive
BC_V for for later spectral types.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 73 287 Mean optical photometry
tablea2.dat 98 289 Mean near-IR photometry
tablea3.dat 66 158 Far-IR colors
tablea4.dat 76 190 Luminosities and extinctions
tablea5.dat 94 55 Colors for main-sequence stars
table.tex 273 1143 AASTeX version of tables A1-A5
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
16- 20 F5.2 mag Vmag []? Average V magnitude
22- 25 F4.2 mag e_Vmag *[]? V error
27- 31 F5.2 mag U-B []? Average U-B color
33- 36 F4.2 mag e_U-B *[]? U-B error
38- 42 F5.2 mag B-V []? Average B-V color
44- 47 F4.2 mag e_B-V *[]? B-V error
49- 53 F5.2 mag V-R []? Average V-R color
55- 58 F4.2 mag e_V-R *[]? V-R error
60- 64 F5.2 mag R-I []? Average R-I color
66- 69 F4.2 mag e_R-I *[]? R-I error
71- 73 I3 --- o_Vmag *[]?=0 Number of V measurements for average
--------------------------------------------------------------------------------
Note on e_Vmag, e_U-B, e_B-V, e_V-R, e_R-I:
The quoted errors are 1 sigma dispersions from the average values
for objects with 2 or more measurements. For convenience the
dispersions are 0.00 for objects with only a single measurement (N_V=1).
Note on o_Vmag:
The number of data points used to determine average colors is usually
close to the number of V measurements
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
16- 20 F5.2 mag Kmag []? Average K magnitude
22- 25 F4.2 mag e_Kmag *[]? K error
27- 31 F5.2 mag J-K []? Average J-K color
33- 36 F4.2 mag e_J-K *[]? J-K error
38- 42 F5.2 mag H-K []? Average H-K color
44- 47 F4.2 mag e_H-K *[]? H-K error
49- 53 F5.2 mag K-L []? Average K-L color
55- 58 F4.2 mag e_K-L *[]? K-L error
60- 64 F5.2 mag K-M []? Average K-M color
66- 69 F4.2 mag e_K-M *[]? K-M error
71- 75 F5.2 mag K-N []? Average K-N color
77- 80 F4.2 mag e_K-N *[]? K-N error
82- 86 F5.2 mag K-Q []? Average K-Q color
88- 91 F4.2 mag e_K-Q *[]? K-Q error
93- 95 I3 --- o_Kmag *[]?=0 Number of K measurements for average
97- 98 I2 --- o_Nmag []?=0 Number of N measurements for average
--------------------------------------------------------------------------------
Note on e_Kmag, e_J-K, e_H-K, e_K-L, e_K-M, e_K-N, e_K-Q:
The quoted errors are 1 sigma dispersions from the average values
for objects with 2 or more measurements. For convenience the
dispersions are 0.00 for objects with only a single measurement (N_V=1).
Note on o_Kmag:
The number of data points used to determine average colors is usually
close to the number of K measurements
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 38 A38 --- Name Star names
40- 45 F6.2 mag K-12 []? K-12 um color
47- 52 F6.2 mag K-25 []? K-25 um color
54- 59 F6.2 mag K-60 []? K-60 um color
61- 66 F6.2 mag K-100 []? K-100 um color
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
15- 18 A4 --- SED Spectral energy distribution class
20- 24 A5 --- Sp Spectral type
26- 30 I5 K Teff []? Effective temperature
32- 36 F5.2 mag AV []? Optical extinction
38- 42 F5.2 mag AJ []? Extinction at 1.25 um
44- 48 F5.2 solLum LJ *[]? Stellar luminosity
50 A1 --- l_LFIR *[< ] L_FIR limiting character
51- 55 F5.2 solLum LFIR []? 7-135 um luminosity
57 A1 --- l_Lb *[> ] L_b limiting character
58- 62 F5.2 solLum Lb []? Bolometric luminosity
64 A1 --- l_LJ/Lb [< ] LJ/Lb limiting character
65- 69 F5.2 --- LJ/Lb []? LJ/Lb ratio
71 A1 --- l_LFIR/Lb [< ] LFIR/Lb limiting character
72- 76 F5.2 --- LFIR/Lb []? LFIR/Lb ratio
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Note on LJ:
The stellar luminosity, LJ, follows the J magnitude, the extinction and an
appropriate bolometric correction from Table A5 for a distance of d=140pc.
Note on l_LFIR:
Luminosity is an upper limit, "<", for sources not detected by IRAS.
Note on l_Lb:
Luminosity is a lower limit, ">", for sources with an incomplete photometry.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Sp Spectral type
6- 10 I5 K Teff Effective temperature
12- 16 F5.2 mag BC Bolometric correction
18- 22 F5.2 mag U-V U-V color
24- 28 F5.2 mag B-V B-V color
30- 34 F5.2 mag V-Rc V-R(Cousins) color
36- 40 F5.2 mag V-Rj V-R(Johnson) color
42- 46 F5.2 mag V-Ic V-I(Cousins) color
48- 52 F5.2 mag V-Ij V-I(Johnson) color
54- 58 F5.2 mag V-J V-J color
60- 64 F5.2 mag V-H V-H color
66- 70 F5.2 mag V-K V-K color
72- 76 F5.2 mag V-L V-L color
78- 82 F5.2 mag V-M []? V-M color
84- 88 F5.2 mag V-N []? V-N color
90- 94 F5.2 mag V-12 []? V-12 um color
--------------------------------------------------------------------------------
References:
Bessell, M. S. 1990a, A&AS, 83, 357 =1990A+AS...83..357B 1990A+AS...83..357B
Bessell, M. S. 1990b, PASP, 102, 1181
Bessell, M. S., & Brett, J. M. 1988, PASP, 100, 1134 =1988PASP..100.1134B 1988PASP..100.1134B
Gliese, W., & Jahreiss, H. 1979, A&AS, 38, 423 =1979A&AS...38..423G 1979A&AS...38..423G
Herbig, G. H., & Bell, K. R. 1988, Lick Obs. Bull., No. 1111
=1988LicOB1111....1H 1988LicOB1111....1H
Johnson, H. L. 1966, ARA&A, 4, 193
Schmidt-Kaler, Th. 1982, in Landolt-Bornstein Tables, Springer, p. 454
Straizys, V. 1992, Multicolor Stellar Photometry, Tucson, Pachart
Origin: AAS CD-ROM series, Volume 5, 1995 Lee Brotzman [ADS] 06-Nov-95
(End) [CDS] 02-Feb-1996