J/ApJ/830/127 CLASSy: CARMA obs. in L1451 region of Perseus (Storm+, 2016)
CARMA Large Area Star Formation Survey: dense gas in the young L1451 region
of Perseus.
Storm S., Mundy L.G., Lee K.I., Fernandez-Lopez M., Looney L.W., Teuben P.,
Arce H.G., Rosolowsky E.W., Meisner A.M., Isella A., Kauffmann J.,
Shirley Y.L., Kwon W., Plunkett A.L., Pound M.W., Segura-Cox D.M.,
Tassis K., Tobin J.J., Volgenau N.H., Crutcher R.M., Testi L.
<Astrophys. J., 830, 127-127 (2016)>
=2016ApJ...830..127S 2016ApJ...830..127S (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interstellar medium ; Velocity dispersion ;
Millimetric/submm sources ; Interferometry
Keywords: ISM: clouds; ISM: kinematics and dynamics; ISM: molecules;
ISM: structure; stars: formation
Abstract:
We present a 3mm spectral line and continuum survey of L1451 in the
Perseus Molecular Cloud. These observations are from the CARMA Large
Area Star Formation Survey (CLASSy), which also imaged Barnard 1,
NGC1333, Serpens Main, and Serpens South. L1451 is the survey region
with the lowest level of star formation activity-it contains no
confirmed protostars. HCO+, HCN, and N2H+ (J=1->0) are all
detected throughout the region, with HCO+ being the most spatially
widespread, and molecular emission seen toward 90% of the area above
N(H2) column densities of 1.9x1021cm-2. HCO+ has the broadest
velocity dispersion, near 0.3km/s on average, compared with ∼0.15km/s
for the other molecules, thus representing a range of subsonic to
supersonic gas motions. Our non-binary dendrogram analysis reveals
that the dense gas traced by each molecule has a similar hierarchical
structure, and that gas surrounding the candidate first hydrostatic
core (FHSC), L1451-mm, and other previously detected single-dish
continuum clumps has similar hierarchical structure; this suggests
that different subregions of L1451 are fragmenting on the pathway to
forming young stars. We determined that the three-dimensional
morphology of the largest detectable dense-gas structures was
relatively ellipsoidal compared with other CLASSy regions, which
appeared more flattened at the largest scales. A virial analysis shows
that the most centrally condensed dust structures are likely unstable
against collapse. Additionally, we identify a new spherical, centrally
condensed N2H+ feature that could be a new FHSC candidate. The
overall results suggest that L1451 is a young region starting to form
its generation of stars within turbulent, hierarchical structures.
Description:
The details of CARMA Large Area Star Formation Survey (CLASSy)
observations, calibration, and mapping are found in Paper I (Storm+,
2014ApJ...794..165S 2014ApJ...794..165S); specifics related to L1451 are summarized here.
We mosaicked a total area of ∼150 square arcminutes in CARMA23 mode,
which uses all 23 CARMA (Combined Array for Research in
Millimeter-wave Astronomy) antennas. The mosaic was made up of two
adjacent rectangles containing a total of 673 individual pointings
with 31" spacing in a hexagonal grid (see Figure 1). The reference
position of the mosaic is at the center of the eastern rectangle:
RAJ2000=03:25:17, DEJ2000=30:21:23. The region was observed for 150
total hours between 2012 Oct and 2013 Jul-Aug.
See section 2 for further details.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 109 113 HCO+ dendrogram leaf and branch properties
table5.dat 109 46 HCN dendrogram leaf and branch properties
table6.dat 109 22 N2H+ dendrogram leaf and branch properties
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See also:
J/ApJ/819/143 : HCO+ and N2D+ dense cores in Perseus (Campbell+, 2016)
J/MNRAS/402/603 : Properties of SCUBA cores in Perseus (Curtis+, 2010)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJ/684/1240 : Prestellar cores in Perseus, Serpens & Oph. (Enoch+, 2008)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/ApJ/683/822 : Star formation in Ophiuchus & Perseus. II. (Jorgensen+, 2008)
J/ApJS/175/509 : Ammonia spectral atlas in Perseus (Rosolowsky+, 2008)
J/ApJ/646/1009 : Structures of dust in Perseus molecular cloud (Kirk+, 2006)
J/ApJ/638/293 : 1.1mm sources in the Perseus Molecular Cloud (Enoch+, 2006)
J/A+A/440/151 : Observations at 850um in Perseus clusters (Hatchell+, 2005)
http://admit.astro.umd.edu/classy/ : CLASSy home page
Byte-by-byte Description of file: table[456].dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Type Dendrogram type ("Branch" or "Leaf")
10- 12 I3 --- Seq [0/112] Source index number
14- 15 I2 h RAh [3] Hour of Right Ascension (J2000) (1)
17- 18 I2 min RAm [24/25] Minute of Right Ascension (J2000) (1)
20- 23 F4.1 s RAs Second of Right Ascension (J2000) (1)
25 A1 --- DE- [+] Sign of the Declination (J2000) (1)
26- 27 I2 deg DEd [30] Degree of Declination (J2000) (1)
29- 30 I2 arcmin DEm [16/26] Arcminute of Declination (J2000) (1)
32- 35 F4.1 arcsec DEs Arcsecond of Declination (J2000) (1)
37- 41 F5.1 arcsec amaj [13/776] Major axis (1)
43- 47 F5.1 arcsec bmin [6/269] Minor axis (1)
49- 53 F5.1 deg PA Position angle (1)
55- 58 F4.2 --- b/a Axis ratio; bmin/amaj
60- 63 F4.2 --- FF Filling factor (2)
65- 69 F5.3 pc Size [0.01/0.5] Size (3)
71- 74 F4.2 km/s [3.3/5.1]? Weighted mean Local Standard of
Rest velocity (4)
76 I1 10-2km/s e_ [1/8]? Uncertainty in
78- 81 F4.2 km/s DelVLSR [0.02/0.3]? Weighted standard deviation of
all fitted VLSR values (5)
83 I1 10-2km/s e_DelVLSR [0/6]? Uncertainty in DelVLSR
85- 88 F4.2 km/s [0.07/0.5]? Weighted mean velocity dispersion
90 I1 10-2km/s e_ [0/9]? Uncertainty in (6)
92- 95 F4.2 km/s Delsig [0.01/0.2]? Weighted standard deviation of
all fitted velocity dispersion values
97 I1 10-2km/s e_Delsig [0/7]? Uncertainty in Delsig (7)
99-102 F4.2 Jy/beam PInt [0.3/2.8] Peak intensity (8)
104-107 F4.1 --- Ctst [2/10]? Contrast (9)
109 I1 --- Level [0/7] Branching level in the dendrogram (10)
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Note (1): Were determined from regionprops in MATLAB. We do not report formal
uncertainties of these values since the spatial properties of
irregularly shaped objects are dependent on the chosen method.
Note (2): Defined as the area of the leaf or branch inscribed within the
fitted ellipse, divided by the area of the fitted ellipse.
Note (3): Defined as the geometric mean of the major and minor axes, for
an assumed distance of 235pc.
Note (4): Weights are determined from the statistical uncertainties reported
by the IDL MPFIT program. The error in the mean was computed as the
standard error of the mean, DelVLSR/sqrt{N}, where N is the number
of beams worth of pixels within a given object. We report kinematic
properties only for objects that have at least three synthesized
beams worth of kinematic pixels.
Note (5): The error was computed as the standard error of the standard
deviation, DelVLSR/2(N-1)0.5, assuming the sample of beams was
drawn from a larger sample with a Gaussian velocity distribution.
Note (6): The error was computed as the standard error of the mean,
Delsig/sqrt{N}.
Note (7): The error was computed as the standard error of the standard
deviation, Delsig/2(N-1)0.5.
Note (8): For a leaf, this is the peak intensity measured in a single channel
in the dendrogram analysis. For a branch, this is the intensity
level where the leaves above it merge together.
Note (9): Defined as the difference between the peak intensity of a leaf and
the height of its closest branch in the dendrogram, divided
by 1-σ{n}.
Note (10): For example, the base of the tree is level 0, so an isolated leaf
that grows directly from the base is considered to be at level 0.
A leaf that grows from a branch one level above the base will be
at level 1, etc.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Jan-2017