J/A+A/640/A27 Protoplanetary disk masses in NGC 2024 (van Terwisga+, 2020)
Protoplanetary disk masses in NGC 2024: evidence for two populations.
van Terwisga S.E., van Dishoeck E.F., Mann R.K., Di Francesco J.,
van der Marel N., Meyer M., Andrews S.M., Carpenter J., Eisner J.A.,
Manara C.F., Williams J.P.
<Astron. Astrophys. 640, A27 (2020)>
=2020A&A...640A..27V 2020A&A...640A..27V (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; Stars, pre-main sequence ;
Millimetric/submm sources ; Stars, masses ; Stars, diameters
Keywords: stars: pre-main sequence - techniques: interferometric -
protoplanetary disks
Abstract:
Protoplanetary disks in dense, massive star-forming regions (SFRs)
are strongly affected by their environment. How this environmental
impact changes over time is an important constraint on disk evolution
and external photoevaporation models.
We characterized the dust emission from 179 disks in the core of the
young (0.5Myr) NGC 2024 cluster. By studying how the disk mass varies
within the cluster, and comparing these disks to those in other
regions, we determined how external photoevaporation influences disk
properties over time.
Using the Atacama Large Millimeter/submillimeter Array (ALMA), a
2.9'x2.9' mosaic centered on NGC 2024 FIR 3 was observed at 225GHz
with a resolution of 0.25'', or ∼100AU. It contains 179 disks
identified at IR wavelengths, 7 new disk candidates, and several
protostars. Of the disks in the sample, 57 are detected. The overall
detection rate is 32±4%. Few of the disks are resolved, with the
exception of a giant (R=300AU) transition disk. Serendipitously, we
observe a millimeter flare from an X-ray bright Young Stellar Object
(YSO), and resolve continuum emission from a Class 0 YSO in the FIR 3
core. Two distinct disk populations are present: a more massive one in
the east, along the dense molecular ridge hosting the FIR 1-5 YSOs,
with a detection rate of 45±7%. In the western population, towards
IRS 1, only 15±4% of disks are detected.
NGC 2024 hosts two distinct disk populations. Disks along the dense
molecular ridge are young (0.2-0.5Myr) and partly shielded from the
FUV radiation of IRS 2b; their masses are similar to isolated 1-3Myr
old SFRs. The western population is older and at lower extinctions,
and may be affected by external photoevaporation from both IRS 1 and
IRS 2b. It is, however, possible these disks had lower masses to begin
with.
Description:
Based on 225GHz ALMA observations, program code 2017.1.01102.S (PI:
R. Mann). taken between Dec. 23 2017 and Jan. 15 2018. Data were
imaged in CASA v. 5.4.0. Disk masses assume a distance of 414 pc to
NGC 2024 (Menten et al. 2007; Bailer-Jones et al. 2018), effective
midplane temperatures of 20K, beta=1, k1000GHz=10cm2/g for the
dust opacity.
Objects:
----------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------
05 41 43 -01 50.5 NGC 2024 = NGC 2024
----------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 53 58 Continuum fluxes and masses for detected disks
table2.dat 32 7 Radii, position angles, and inclinations for
resolved disks
tableb1.dat 42 122 3-sigma continuum flux and mass upper limits
for nondetected disks
list.dat 136 2 List of fits images
fits/* . 2 Individual fits images
--------------------------------------------------------------------------------
See also:
J/ApJ/598/375 : Chandra X-ray observations of NGC 2024 (Skinner+, 2003)
J/AJ/126/1665 : NICMOS observations of NGC 2024 (Liu+, 2003)
J/ApJ/646/1215 : Low-mass stars and brown dwarfs in NGC 2024 (Levine+, 2006)
J/ApJ/787/109 : Age estimates for NGC 2024 and ONC stars (Getman+, 2014)
J/ApJ/802/77 : Protoplanetary disk masses in NGC 2024 cluster (Mann+, 2015)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Name Source ID (G1)
9- 17 F9.6 deg RAdeg Right ascension (J2000)
19- 27 F9.6 deg DEdeg Declination (J2000)
29- 33 F5.1 mJy Flux Continuum flux at 225GHz
35- 39 F5.2 mJy e_Flux Continuum flux at 225GHz error
41- 46 F6.1 Mgeo Mass ?=-99 Inferred disk mass (in Mearth units)
48- 53 F6.2 Mgeo e_Mass ?=-99 Inferred disk mass error (in Mearth units)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Name Source ID (G1)
8- 10 I3 AU Rmaj Disk major axis
12- 13 I2 AU e_Rmaj Error on major axis
15- 17 I3 deg PA Disk position angle
19- 23 F5.1 deg e_PA ?=-99 Disk position angle error
25- 26 I2 deg inc Disk inclination
28- 32 F5.1 deg e_inc ?=-99 Error on disk inclination
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Name Source ID (G1)
9- 17 F9.6 deg RAdeg Right ascension (J2000)
19- 27 F9.6 deg DEdeg Declination (J2000)
29 I1 --- l_Flux [1] Upper limit flag on Flux (1 for upper limit)
31- 34 F4.1 mJy Flux 3-sigma continuum flux at 225GHz upper limit
36 I1 --- l_Mass [1] Upper limit flag on Mass (1 for upper limit)
38- 42 F5.1 Mgeo Mass 3-sigma mass upper limit (in Mearth units)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 52 A23 --- Nz Number of pixels along Z-axis
54- 58 I5 Kibyte size Size of FITS file
60-108 A49 --- FileName Name of FITS file, in subdirectory fits
110-136 A27 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Global notes:
Note (G1): Source ID:
IRC NNNA from Meyer M.R., 1996, PhD thesis University of Massachusetts
IRS 2 = [BCB89] IRS 2 in Simbad (No 232 in Meyer, 1996)
--------------------------------------------------------------------------------
Acknowledgements:
Sierk van Terwisga, terwisga(at)mpia.de
(End) Patricia Vannier [CDS] 28-Apr-2020