A molecular line study towards massive extended green object clumps in the southern sky: chemical properties

Abstract

We present a molecular line study towards 31 extended green object (EGO) clumps in the southern sky using data from MALT90 (Millimetre Astronomy Legacy Team 90 GHz). According to previous multiwavelength observations, we divide our sample into two groups: massive young stellar objects (MYSOs) and HII regions. Our results seem to support that N2H+ and C2H emissions mainly come from the gas inside quiescent clumps. In addition, we also find that the [N2H+]/[H13CO+] and [C2H]/[H13CO+] relative abundance ratios decrease from MYSOs to HII regions. These results suggest depletion of N2H+ and C2H in the late stages of massive-star formation, probably caused by the formation of HII regions inside. N2H+ and C2H might be used as chemical clocks for massive-star formation by comparing with other molecules such as H13CO+ and HC3N.

References in corpus (10)

• Cold Dark Clouds: The Initial Conditions for Star Formation
• A Catalog of Extended Green Objects (EGOs) in the GLIMPSE Survey: A new sample of massive young stellar object outflow candidates
• On the frequency of N2H+ and N2D+
• The RMS Survey: Radio observations of candidate massive YSOs in the southern hemisphere
• ATLASGAL --- Complete compact source catalogue: 280\degr\ $<\ell <$ 60\degr
• Ethynyl (C2H) in massive star formation: Tracing the initial conditions?
• The Excitation of N${}_2$H${}^{+}$ in Interstellar Molecular Clouds. I - Models
• A Molecular Line Observation toward Massive Clumps Associated with Infrared Dark Clouds
• Physical and chemical conditions in methanol maser selected hot-cores and UCHII regions
• Physical and chemical properties of Red MSX Sources in the southern sky: HII regions

Cited by in corpus (17)

• The ALMA Survey of 70 $\mu$m dark High-mass clumps in Early Stages (ASHES). I. Pilot Survey: Clump Fragmentation
• Far-Infrared Dust Temperatures and Column Densities of the MALT90 Molecular Clump Sample
• Survey Observations to Study Chemical Evolution from High-mass Starless Cores to High-mass Protostellar Objects I: HC3N and HC5N
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- XII: Fragmentation and multi-scale gas kinematics in protoclusters G12.42+0.50 and G19.88-0.53
• Survey Observations to Study Chemical Evolution from High-Mass Starless Cores to High-Mass Protostellar Objects II. HC${}_3$N and N${}_2$H${}^{+}$
• Initial phases of high-mass star formation: A multiwavelength study towards the extended green object G12.42+0.50
• Chemical evolution of Red MSX Sources in the southern sky
• Infrared dust bubble CS51 and its interaction with the surrounding interstellar medium
• SiO Outflows in the Most Luminous and Massive Protostellar Sources of the Southern Sky
• MALT90 molecular content on high-mass IR-dark clumps
• Chemical evolution of N2H+ in six massive star-forming regions
• Gas Kinematics in the HII regions G351.69-1.15 and G351.63-1.25
• Sulfur-bearing molecules in a sample of early star-forming cores
• Chemical Evolution of HC3N in Dense Molecular Clouds
• Cyanopolyyne line survey towards high-mass star-forming regions with TMRT
• A Possible Chemical Clock in High-mass Star-forming Regions: N(HC3N)/N(N2H+)?
• Studying a precessing jet of a massive young stellar object within a chemically rich region