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J/A+A/579/A80       Star-forming regions deuteration         (Gerner+, 2015)

Chemical evolution in the early phases of massive star formation. II. Deuteration. Gerner T., Shirley Y.L., Beuther H., Semenov D., Linz H., Albertsson T., Henning T. <Astron. Astrophys., 579, A80-80 (2015)> =2015A&A...579A..80G (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Spectroscopy Keywords: stars: formation - stars: early-type - ISM: molecules - evolution - astrochemistry Abstract: The chemical evolution in high-mass star-forming regions is still poorly constrained. Studying the evolution of deuterated molecules allows distinguishing between subsequent stages of high-mass star formation regions based on the strong temperature dependence of deuterium isotopic fractionation. We observed a sample of 59 sources including 19 infrared dark clouds, 20 high-mass protostellar objects, 11 hot molecular cores and 9 ultra-compact HII regions in the (3-2) transitions of the four deuterated molecules, DCN, DNC, DCO+, and N2D+ as well as their non-deuterated counterparts. The overall detection fraction of DCN, DNC, and DCO+ is high and exceeds 50% for most of the stages. N2D+ was only detected in a few infrared dark clouds and high-mass protostellar objects. This may be related to problems in the bandpass at the transition frequency and to low abundances in the more evolved, warmer stages. We find median D/H ratios of 0.02 for DCN, 0.005 for DNC, 0.0025 for DCO+, and 0.02 for N2D+. While the D/H ratios of DNC, DCO+, and N2D+ decrease with time, DCN/HCN peaks at the hot molecular core stage. We only found weak correlations of the D/H ratios for N2D+ with the luminosity of the central source and the FWHM of the line, and no correlation with the H2 column density. In combination with a previously observed set of 14 other molecules (Paper I), we fitted the calculated column densities with an elaborate 1D physico-chemical model with time-dependent D-chemistry including ortho- and para-H2 states. Good overall fits to the observed data were obtained with the model. This is one of the first times that observations and modeling were combined to derive chemically based best-fit models for the evolution of high-mass star formation including deuteration. Description: The sources were taken from Gerner et al. (2014, Cat. J/A+A/563/A97) and were initially selected from different source lists. The total sample contains 59 high-mass star-forming regions, consisting of 19 IRDCs and 20 HMPOs as well as 11 HMCs and 9 UCHIIs. The sources were selected from well-known source catalogs of the literature without specific selection criteria such as spherical symmetry. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tablea1.dat 83 59 Source list showing the position, the distance, and the evolutionary stage of all high-mass star-forming regions tablea2.dat 98 59 Luminosity, H2, DCO+, DCN, DNC, and N2D+ column density and the corresponding error for each source tablea3.dat 75 59 HCO+, HCN, HNC, and N2H+ column density and corresponding error for each source
See also: J/A+A/563/A97 : IRAM 30m reduced spectra of 59 sources (Gerner+, 2014) Byte-by-byte Description of file: tablea1.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Source Source name 13- 14 I2 h RAh Right ascension (J2000) 16- 17 I2 min RAm Right ascension (J2000) 19- 22 F4.1 s RAs Right ascension (J2000) 24 A1 --- DE- Declination sign (J2000) 25- 26 I2 deg DEd Declination (J2000) 28- 29 I2 arcmin DEm Declination (J2000) 31- 32 I2 arcsec DEs Declination (J2000) 34- 40 F7.3 deg GLON Galactic longitude 42- 48 F7.3 deg GLAT Galactic latitude 50- 54 F5.2 kpc Dist Distance (preferred one) 55 A1 --- n_Dist [deh] Note on Dist (1) 57- 61 F5.2 kpc Dist2 ? Alternative distance 62 A1 --- n_Dist2 [fij] Note on Dist2 (1) 64- 68 A5 --- Type Stage of source (4) 70 A1 --- 24um [yn- ] Embedded IRDC 24um point source ? (2) 72 A1 --- 70um [yn- ] Embedded IRDC 70um point source ? (2) 73 A1 --- n_70um [cg] Note on 70um (3) 76- 83 A8 --- Ref Sources of the dust continuum data (5)
Note (1): Distance notes as follows: d = For vlsr = 111.3km/s (preferred) or 97.6km/s (alternative) e = For vlsr = 100.2km/s (preferred) or 52.8km/s (alternative) f = For vlsr = 94.3km/s (preferred) or 98.4km/s (alternative) h = Ellsworth-Bowers et al. (2015ApJ...799...29E, Cat. J/ApJ/799/29) i = For the near (far) kinematic solution j = Parallactic (kinematic) distance Note (2): For the IRDCs we indicate whether or not they show embedded 24 or 70µm point sources with y(es) or n(o) (or "-" if there are no data available). Note (3): Note on 70um as follows: c = Very weak emission compared with the background located at the same position as 24um emission source. g = No embedded central point source found, a nearby extended source with emission inside the beam is detected. Note (4): the four stages are: IRDC = Infra-Red Cark Cloud stage (densities ≳105cm-3) HMPO = High-Mass protostellar Object (accreting protostar >8M☉) HMC = Hot Molecular Core (central source heats the surrounding environment) UCHII = Ultra-Compact HII region (UV radiation from protostar ionizes the surrounding gas) Note (5): Dust continuum data as follows: ATLASGAL = galactic plane survey ATLASGAL (870um; Schuller et al., 2009A&A...504..415S) Mambo = IRAM 30m observations with Mambo (1.2mm) SCUBA = SCUBA Legacy Catalog (850um; Di Francesco et al., 2008ApJS..175..277D, Cat. J/ApJS/175/277)
Byte-by-byte Description of file: tablea2.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Source Source name 13- 17 F5.2 [Lsun] logL ? Luminosity 18 A1 --- r_logL [a-i] Luminosity reference (2) 20- 26 E7.2 cm-2 NH2 H2 column density (1) 28- 29 A2 --- l_DCO+ [≤ ] Limit flag on DCO+ 30- 36 E7.2 cm-2 DCO+ DCO+ column density 38- 44 E7.2 cm-2 e_DCO+ rms uncertainty on DCO+ measured integrated flux 46- 47 A2 --- l_DCN [≤ ] Limit flag on DCN 48- 54 E7.2 cm-2 DCN DCN column density 56- 62 E7.2 cm-2 e_DCN rms uncertainty on DCN measured integrated flux 64- 65 A2 --- l_DNC [≤ ] Limit flag on DNC 66- 72 E7.2 cm-2 DNC ?=- DNC column density 74- 80 E7.2 cm-2 e_DNC rms uncertainty on DNC measured integrated flux 82- 83 A2 --- l_N2D+ [≤ ] Limit flag on N2D+ 84- 90 E7.2 cm-2 N2D+ ?=- N2D+ column density 92- 98 E7.2 cm-2 e_N2D+ rms uncertainty on N2D+ measured integrated flux
Note (1): H2 column density is averaged over a 29"-beam and for all other molecules over a 30"-beam. Note (2): References as follows: a = Ragan et al. (2012A&A...547A..49R, Cat. J/A+A/547/A49) b = Beuther et al. (2012A&A...538A..11B, Cat. J/A+A/538/A11) c = Sridharan et al. (2002ApJ...566..931S) d = Linz et al. (2005A&A...429..903L) e = Churchwell et al. (1990A&AS...83..119C) f = Chen et al. (2006ApJ...639..975C) g = Campbell et al. (1995ApJ...454..831C) h = Beuther et al. (2004ApJ...616L..31B) i = Wood & Churchwell (1989ApJ...340..265W)
Byte-by-byte Description of file: tablea3.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Source Source name 13- 19 E7.2 cm-2 HCO+ HCO+ column density 21- 27 E7.2 cm-2 e_HCO+ rms uncertainty on HCO+ measured integrated flux and the optical depth τ (1) 29- 35 E7.2 cm-2 HCN ?=- HCN column density 37- 43 E7.2 cm-2 e_HCN ?=- rms uncertainty on HCN measured integrated flux and the optical depth τ (1) 45- 51 E7.2 cm-2 HNC HNC column density 53- 59 E7.2 cm-2 e_HNC rms uncertainty on HNC measured integrated flux and the optical depth τ (1) 61- 67 E7.2 cm-2 N2H+ N2H+ column density 69- 75 E7.2 cm-2 e_N2H+ rms uncertainty on N2H+ measured integrated flux and the optical depth τ (1)
Note (1): The high uncertainties are in some cases due to high uncertainties in the determined optical depth.
References: Gerner et al., Paper I 2014A&A...563A..97G, Cat. J/A+A/563/A97
(End) Patricia Vannier [CDS] 06-Oct-2015
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