ADC/CDS Standard Document for Catalog:/journal_tables/ApJS/125/161/
ADC/CDS Standard Document for Catalog:| 1. Use the ADC Data Viewer Suite to visualize the data. |
|
| 2. Get the data files via anonymous FTP. (See Note.) |
|
J/ApJS/125/161 A database of dense cores mapped in ammonia (Jijina+, 1999)
================================================================================
Dense cores mapped in ammonia: a database.
Jijina J., Myers P.C., Adams F.C.
<Astrophys. J. Suppl. Ser. 125, 161 (1999)>
=1999ApJS..125..161J
================================================================================
ADC_Keywords: YSOs ; Stars, pre-main sequence ; Radio lines
Keywords: ISM: clouds - ISM: molecules - radio lines: ISM -
stars: pre-main-sequence
Abstract:
We present a database of 264 cores mapped in the (J,K)=(1,1) and (2,2)
lines of NH_3_. We list the core gas properties-peak positions, total
ammonia column densities, intrinsic line widths, kinetic temperatures,
volume densities, core sizes, aspect ratios, and velocity gradients,
as well as the properties of associated young stellar objects
(YSOs)-associated IRAS sources along with their luminosities and
core-YSO distances, outflow velocities, and SIMBAD and cluster
associations. We also present the results of our statistical analysis
and enumerate important pairwise correlations among the various gas
and YSO properties.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 128 339 Core location, method of observation, and references
tablea2.dat 84 339 Core gas properties
tablea3.dat 92 339 YSO properties
tablea4.dat 80 253 Comments on individual sources
refs.dat 74 152 References
--------------------------------------------------------------------------------
See also:
J/A+A/308/573 : Ammonia on YSOs IRAS sources (Molinari+ 1996)
J/A+AS/124/385 : Dense molecular cores. V. (Zinchenko+ 1997)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Datase reference number (G1)
4 A1 --- n_Seq Note on Seq (G2)
6- 21 A16 --- Name Source name of the core (3)
23- 24 I2 h RAh Right ascension (1950) (4)
26- 27 I2 min RAm Right ascension (1950)
29- 32 F4.1 s RAs Right ascension (1950)
34 A1 --- DE- Declination sign (1950)
35- 36 I2 deg DEd Declination (1950)
38- 39 I2 arcmin DEm Declination (1950)
41- 42 I2 arcsec DEs Declination (1950)
44- 49 A6 --- Tel Observational parameters (5)
51- 59 A9 --- SFR Name of the prominent star-forming region, to
which the dense core belongs, or the Bok
globule name where relevant.
61- 64 F4.2 kpc Dist ? Distance to the core
65 A1 --- n_Dist [u?] Uncertainty flag on Dist
67- 81 A15 --- ref(1) References, in refs.dat file (6)
84-108 A25 --- ref(2) References, in refs.dat file (6)
110-128 A19 --- Names Other names of the core
--------------------------------------------------------------------------------
Note (3): When the core has been picked for observation as a consequence
of its association with an IRAS source, it is named accordingly.
Note (4): Position of the peak of the NH_3_(1,1) map.
Note (5): The letter code followed by a numerical value provides the
telescope name (beam width) and spectral resolution, respectively, of
the measurement process.
E = Effelsburg, 40"
H = Haystack, 88"
P = Parkes, 84"
VD = VLA, D configuration, 3"
VC = VLA, C configuration, 1.1"
G = Green Bank 1.3"
S = SRC Appleton, 2.2"
The spectral resolution is given in km/s.
Note (6): Relevant references to the literature.
ref(1): References to articles that include the NH_3_ maps and the
associated core gas properties. These articles often also include
information on the YSOs and other star formation signatures such as
outflows and HH objects that are associated with the NH_3_ cores.
ref(2): References to articles that contain relevant information other
than the NH_3_ core gas properties. This information includes dust and
submillimeter/millimeter continuum maps, maps in some other relevant
molecular transitions, optical and near-infrared (NIR) surveys of the
region inclusive of and adjacent to the core, information on
associated outflows, and HH objects.
These two categories of references are demarcated by a semicolon and a
space in Table A1. The citations for all database references are
provided in the refs.dat file.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Database reference number (G1)
4 A1 --- n_Seq Note on Seq (G2)
6- 21 A16 --- Name Name of the NH_3_(1,1) source
23- 26 F4.1 [cm-2] logNNH3 ? Logarithm (log_10_) of the total NH_3_
column density, N_(NH_3_)/cm^-2^ (3)
27 A1 --- u_logNNH3 [u] Uncertainty code (4)
29- 33 F5.2 km/s DVint ? Intrinsic line widths (5)
34 A1 --- u_DVint [mu] Uncertainty code (4)
36- 40 F5.1 K Tkin ? Kinetic temperature (6)
41 A1 --- u_Tkin [amru] Uncertainty code (4)
43- 45 F3.1 [cm-3] logNtot ? Logarithm of the total volume density of the
molecule of mean mass (7)
46 A1 --- u_logNtot [um] Uncertainty code (4)
48- 51 F4.2 pc R ? Core size (8)
52 A1 --- u_R [u] Uncertainty code (4)
54- 56 F3.1 --- a/b ? Projected aspect ratio (9)
58- 63 F6.2 km/s/pc VGrad ? Velocity gradient of the core (10)
64 A1 --- u_VGrad [u] Uncertainty code (4)
66- 92 A27 --- Names Other names of the NH_3_(1,1) source
--------------------------------------------------------------------------------
Note (3): These numerical values are listed as provided by the observing
authors. For the method of derivation of this physical quantity see,
for example, Tieftrunk et al. (1998A&A...336..991T).
Note (4): Uncertain codes:
a = assumed
m = averaged over entire core
r = rotation (temperature)
u = uncertain for unspecified reason
Note (5): The widths are corrected by most authors for line broadening
due to hyperfine and spectral resolution effects. The latter are
assumed to add in quadrature. If this correction has not already been
made by the reporting authors, we have made it ourselves.
Note (6): Kinetic temperature as computed via measurements in the (1,1)
and (2,2) lines by the reporting authors. Some authors report rotation
temperatures, T_rot_, in lieu of T_kin_. These are sufficiently
accurate substitutes for kinetic temperatures for small T_rot_ (Ho &
Townes, 1983ARA&A..21..239H; Walmsley & Ungerechts, 1983A&A...122..164W).
Assumed kinetic temperatures are sometimes also reported when
measurements of the (2,2) spectra are absent. Both rotation
temperatures and assumed kinetic temperatures have been marked by
letter codes that follow the numerical values for these quantities.
Reported kinetic temperatures greater than 40K are likely to require a
significant correction due to the recalibration of the interstellar
ammonia thermometer (Danby et al., 1988MNRAS..235..229D). In Table A2
we reproduce the kinetic temperatures reported in the literature. We
do, however, make the requisite corrections (if not made by the
reporting authors) for purposes of the statistical analysis.
Note (7): n_tot/cm^-3^=1.2n(H_2_) (assuming one He atom for every five
H_2_ molecules). These are listed as provided by the authors. For the
method of derivation of this physical quantity, see for example, Ho &
Townes (1983ARA&A..21..239H).
Note (8): The convention used to calculate R is R=(ab)^1/2^/2, where
a,b are major and minor axes of the approximate ellipse formed by the
HM intensity contour of the NH_3_(1,1) map. If the literature source
reported a core size computed via this definition, we have reproduced
it as listed. However, if an alternate definition was used by the
author, we have recomputed R using the above definition. No
deconvolution of the beam size has been attempted.
Note (9): a/b, where a,b are major and minor axes of the approximate
ellipse formed by the HM NH_3_(1,1) intensity contour of the core. See
Appendix C for a pictorial representation of the definition of a core.
Note (10): The majority of these entries are taken directly from Goodman
et al. (1993ApJ...406..528G). The gradient {lapla}v_lsr_ is calculated
by fitting a two-dimensional linear function to v_lsr_ in the plane of
the sky as expected for solid-body rotation.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Database reference number
4 A1 --- n_Seq Note on Seq (G2)
6- 21 A16 --- Name Name of the NH_3_(1,1) source.
25- 35 A11 --- IRAS Name of the IRAS source, if there is one
associated with the dense core (2)
37 A1 --- l_log(Liras) Limit flag on log(Liras)
38- 42 F5.2 [solLum] log(Liras) ? IRAS luminosity (3)
43 A1 --- u_log(Liras) [u] u: uncertain for unspecified reason.
45- 48 F4.2 pc Dist ? Projected distance of the IRAS source from
the peak position of the NH_3_(1,1) map
49 A1 --- n_Dist [u] u: uncertainty
51- 55 F5.1 km/s Vout ? Outflow velocity, if there is an outflow
known to be associated with the core (4)
56 A1 --- n_Vout [o] o: outflow velocity measurement made at
position other than at the powering
IRAS source (perhaps powered by some
other source)
58 I1 --- NIRAS ? Number of IRAS sources associated with the
NH_3_ core
59- 60 A2 --- n_NIRAS [na ] Not analysed
62 A1 --- l_NSimbad [~] Limit flag on NSIMBAD
63- 65 I3 --- NSimbad ? Estimate of the number of non-IRAS sources
projected within 2 core radii of the peak
position as reported by the SIMBAD
database (5)
66- 67 A2 --- n_NSimbad [na ] Not analysed
69 A1 --- Ass [yn] Cluster association (yes/no) (6)
70 A1 --- u_Ass [?] Uncertainty flag on Ass (6)
71- 72 A2 --- n_Ass [na] Not analysed
73-102 A30 --- Names Other names
--------------------------------------------------------------------------------
Note (2): A source is considered associated in general if it lies within
2 core radii and if there is sufficient evidence of YSO redness (see
Appendix C). We have used a simple redness criterion for the IRAS
fluxes, viz., the flux density at two or more adjacent IRAS
wavelengths must increase with wavelength. Entries with as many as
three upper limits on IRAS fluxes have been included (the nonlimit,
accurate value belonging to any of the three largest wavelengths) if
there is an increase in flux with increasing wavelength across all
IRAS wavelengths, i.e., evidence that the source is associated with
the core gas. Often there is other evidence of association such as an
outflow (powered by the IRAS source) that clearly interacts with the
core.
Note (3): This is calculated systematically by linearly interpolating the
IRAS Point Source Catalog (PSC) fluxes, making a long-wavelength
bolometric correction (Myers et al., 1987ApJ...319..340M) and a
short-wavelength correction (Ladd et al., 1991ApJ...382..555L).
Note (4): In most cases the associated IRAS source is believed to power
the outflow. Entries that do not satisfy this criterion are so
indicated. Most of the entries in this column are taken from Wu,
Huang, & He (1996A&AS..115..283W). The convention used to measure
outflow velocity by these authors is essentially the full line width
at 0.1 or 0.2K above zero temperature level.
Note (5): A systematic search was made for SIMBAD objects within 2 core
radii of the NH_3_(1,1) peak. Attempts were made to eliminate double
counting and to include only such objects as can be considered to be
independent sources, e.g., radio sources, FU Orionis stars,
emission-line stars, and X-ray sources. Masers and HH objects were not
considered to be independent sources. Despite this systematic
screening, it was impossible to differentiate projected sources from
associated ones. Hence the numerical estimate provided in this column
must be interpreted exactly as what it is, viz., an estimate of the
projected SIMBAD sources and nothing more. Table A4 lists the nature
of these sources. It also lists the nonsource SIMBAD objects such as
HH objects and masers.
Note (6): Indicates whether or not the NH_3_(1,1) core is associated with
a cluster of stars. A cluster is generally a conglomerate of 30 or
more embedded stars. A substantial fraction of this information comes
from the Hodapp (1994, Cat. <J/ApJS/94/615>) survey. This study is
complete (90% recovery) down to K'=16.5. Other studies utilized for
the purpose (references provided in Table A1) have different
completeness limits. Some have sufficient information to subtract the
background star fraction and even approximate stellar masses; most do
not. Our greater than 30 star criterion differs from the definition of
five or more stars used by Hodapp (1994, Cat. <J/ApJS/94/615>).
However, since there are only a handful of Hodapp clusters with fewer
than 30 embedded stars that overlap with the contents of our database,
our definition supersedes his for those cases. The criterion for
cluster association used in our paper is as defined in Appendix C. In
cases where there is insufficient information to deduce the status of
the cluster association of a core, we resort to using a simple
formula, viz., if the IRAS source associated with the core has a
bolometric luminosity, L_bol_>10^4^L_{sun}_, we assume cluster
association and conversely. We adopt this criterion because all but a
handful of cores with associated IRAS sources that do meet this
criterion are independently and clearly established to be associated
with a cluster. The error caused by such an approximation weights
against cluster association for low-luminosity sources, as it is
possible to find such sources alongside the highly luminous ones in
large clusters. Nevertheless, this is the best that can be done, given
the scarcity of stellar cluster information in these cases. The
database entries that utilize this scheme to determine cluster
association have been so indicated by a question mark following the
"y" or "n".
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Database reference number
5- 80 A76 --- Com Relevant comments for each database entry (1)
--------------------------------------------------------------------------------
Note (1): This pertains to the gas and YSO properties as well as any
other information that we consider germane. Projected SIMBAD objects
are listed separately for convenience. Here we list SIMBAD objects
projected within 2 core radii of the NH_3_(1,1) peak: those considered
to be individual sources, e.g., radio, X-ray, or NIR sources, as well
as those not considered to be stellar sources, e.g., HH objects or
masers.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Ref Ref number
5- 23 A19 --- BibCode BibCode
25- 51 A27 --- Aut Author's name
53- 74 A22 --- Com Comments
--------------------------------------------------------------------------------
Global Notes:
Note (G1): Repeat entries represent cores for which there is more than
one associated IRAS source.
Note (G2): Both categories of entries marked by ] or } are excluded
from the analysis for the sake of consistency of the definition of an
independent core:
]: additional nonpeak or secondary peak measurements of independent
cores for which peak measurements have already been reported.
}: VLA measurements
History: From ApJS electronic version
================================================================================
(End) James Marcout, Patricia Bauer [CDS] 20-Jan-2000