Serpens cloud

Serpens cloud
Name	Serpens cloud
Type	Molecular cloud complex
Epoch	J2000
Ra	18h 30m (approx.)
Dec	+01° (approx.)
Distance	~400–700 pc
Constellation	Serpens
Major features	Serpens Main, Serpens South, W40
Notable objects	IRAS sources, Herbig–Haro objects, Young Stellar Objects

Serpens cloud

The Serpens cloud is a nearby molecular cloud complex notable for active star formation near the constellations Serpens Caput, Aquila Rift, and Ophiuchus that has been targeted by surveys from observatories such as Spitzer Space Telescope, Herschel Space Observatory, Chandra X-ray Observatory, James Clerk Maxwell Telescope, and the Atacama Large Millimeter/submillimeter Array. The region hosts clusters and filaments including Serpens Main and Serpens South and contains protostars, Herbig Ae/Be stars, and compact cores revealed by maps from the Infrared Astronomical Satellite and follow-up studies with the Very Large Array and Submillimeter Array. Interest in the complex arises from comparisons with regions like Taurus Molecular Cloud, Orion Nebula, and Perseus molecular cloud for studies of low- and intermediate-mass star formation.

Overview

The cloud complex lies projected against the Milky Way near Sagittarius Arm features and interacts with adjacent formations such as the Aquila Rift and the Pipe Nebula region. Early radio and infrared surveys by IRAS and molecular-line mapping campaigns at facilities like the Nobeyama Radio Observatory established CO and NH3 emission associated with dense clumps. Studies linking data from 2MASS, WISE, Spitzer, and ground-based telescopes produced catalogs of Young Stellar Objects and embedded clusters that have been used in comparative analyses with objects cataloged by Henry Draper Catalogue and emission-line surveys at Palomar Observatory.

Structure and Components

The complex contains multiple subregions, dense cores, and filamentary networks identified in continuum and line tracers such as CO, C18O, N2H+, and HCO+. Observations with Herschel Space Observatory and Planck revealed dust temperature and column density structure, while interferometric imaging by ALMA and the IRAM 30m telescope resolved disks and protostellar envelopes. The arrangement includes clustered populations comparable to those in IC 348 and NGC 1333, and contains compact H II regions akin to those in W49 though at much smaller scales. Magnetic field morphology inferred from polarimetry at JCMT and SOFIA is often compared with measurements in the Perseus cloud and Barnard 68.

Star Formation and Protostars

Embedded protostellar objects span Class 0 to Class III evolutionary stages identified by spectral energy distributions from Spitzer Space Telescope and X-ray activity recorded by Chandra X-ray Observatory. Outflows and jets produce Herbig–Haro objects visible in optical surveys from Hubble Space Telescope and narrowband imaging at Kitt Peak National Observatory. Accretion signatures and disk properties have been modeled using spectroscopy from the Very Large Telescope and photometry from Keck Observatory instruments, with comparisons to protostellar systems in Lupus (constellation) and Chamaeleon I.

Molecular Composition and Chemistry

Chemical inventories derived from millimeter spectroscopy include abundant CO isotopologues, complex organic molecules detected with IRAM and SMA, and sulfur-bearing species observed by Nobeyama Radio Observatory. Comparison of abundances with those in the Orion KL region and in dense cores cataloged by the Ridge et al. surveys informs chemical differentiation studies. Deuterated species and ion-molecule chemistry traced by N2D+ and H2D+ correlate with cold, dense zones similar to findings toward L1544 and Barnard 5.

Observations and Surveys

Major observational campaigns that have focused on the complex include targeted programs with Spitzer Space Telescope's c2d legacy project analogs, far-infrared mapping by Herschel Gould Belt Survey, and X-ray censuses by Chandra teams. Ground-based mm/submm surveys by JCMT Gould Belt Survey and interferometric follow-ups with ALMA and SMA produced catalogs of cores comparable in scope to surveys of Taurus Molecular Cloud and the Orion A molecular cloud. Time-domain monitoring with facilities like Kepler (spacecraft) K2 campaign and ground-based arrays has revealed variable accretion and eruptive young stars similar to FU Orionis and EX Lupi classes.

Notable Subregions

Notable subregions include Serpens Main with dense filaments and embedded clusters studied by teams using Spitzer and Herschel; Serpens South, discovered in infrared surveys and notable for its protostellar-rich filament similar to structures in Aquila Rift; and the W40 region, an H II/molecular interface comparable to M17 and NGC 2024 in morphology. Individual objects include IRAS-identified protostars, compact radio sources observed with the VLA, and optical emission-line knots cataloged in HH object lists maintained by George Herbig-linked research groups.

Distance and Kinematics

Distance estimates to portions of the complex vary, with parallax and spectrophotometric constraints placing components at roughly 400–700 parsecs. Results from Gaia parallaxes refined cluster distances and proper motions, enabling kinematic comparisons with neighboring clouds like the Aquila Rift and streaming motions documented in surveys by the Milky Way Project. Molecular-line velocity fields measured in CO and NH3 reveal complex kinematics including inflow, outflow, and turbulence analogous to dynamics observed in Serpens-like star-forming regions such as Perseus and Orion B.

Category:Star-forming regions