Optical Spectroscopy of the Surface Population of the ρ Ophiuchi Molecular Cloud: The First Wave of Star Formation

By B. Wilking, M. Meyer, John G. Robinson, T. Greene. 2005

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We present the results of optical spectroscopy of 139 stars obtained with the Hydra multiobject spectrograph. The objects extend over a 1.3 deg2 area surrounding the main cloud of the ρ Oph complex. The objects were selected from narrowband images to have Hα in emission. Using the presence of strong Hα emission, lithium absorption, location in the Hertzsprung-Russell diagram, or previously reported X-ray emission, we were able to identify 88 objects as young stars associated with the cloud. Strong Hα emission was confirmed in 39 objects with line widths consistent with their origin in magnetospheric accretion columns. Two of the strongest emission-line objects are young, X-ray-emitting brown dwarf candidates with M8 spectral types. Comparisons of the bolometric luminosities and effective temperatures with theoretical models suggest a median age for this population of 2.1 Myr, which is significantly older than the ages derived for objects in the cloud core. It appears that these stars formed contemporaneously with low-mass stars in the Upper Scorpius subgroup, likely triggered by massive stars in the Upper Centaurus subgroup.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/02470155db5c266e91633614832b05c57ba9bcc9

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In Astronomy and Astrophysics

1. S. Andrews
2. D. Wilner
3. N. Evans II
4. Jonathan P. Williams
5. C. Dullemond
6. A. Hughes
7. T. Birnstiel
8. A. Kraus

Citations in the corpus

• IDENTIFYING THE YOUNG LOW-MASS STARS WITHIN 25 PC. I. SPECTROSCOPIC OBSERVATIONS (2009, background): “The more recent TiO-7140 index, defined by Wilking et al. (2005), is the ratio of the mean flux in two 50 Å bands: the “continuum” band centered on 7035 Å and the TiO band on 7140 Å.”
• A Submillimeter View of Circumstellar Dust Disks in ρ Ophiuchi (2007, methodology): “…1981; Myers et al. 1987; Herbig & Bell 1988; Bouvier & Appenzeller 1992; Vrba et al. 1993; Herbst et al. 1994; Greene&Meyer 1995; Luhman& Rieke 1999;Wilking et al. 1999, 2005; Chavarrı́a et al. 2000; Prato et al. 2003; Doppmann et al. 2003, 2005; Eisner et al. 2005; GrasVelázquez & Ray 2005;…”
• THE SPITZER c2d LEGACY RESULTS: STAR-FORMATION RATES AND EFFICIENCIES; EVOLUTION AND LIFETIMES (2008, background): “A somewhat older population in Ophiuchus, with ages around 2 Myr, was later established by Wilking et al. (2005).”
• PROTOPLANETARY DISK STRUCTURES IN OPHIUCHUS (2009, methodology): “We constructed the DoAr 25 SED from optical data (Vrba et al. 1993; Wilking et al. 2005), the 2MASS database (Cutri et al. 2003), Spitzer observations (Evans et al. 2003; Padgett et al. 2008), and single-dish millimeter photometry (André & Montmerle 1994; Dent et al. 1998; Andrews & Williams…”
• Mapping the Shores of the Brown Dwarf Desert. I. Upper Scorpius (2007, methodology): “The initial target list was made by compiling targets from Herbig & Bell (1988), Bouvier & Appenzeller (1992), Meyer et al. (1993), Martin et al. (1998), Preibisch et al. (1998), Luhman & Rieke (1999), Wilking et al. (2005), Cieza et al. (2010), and Erickson et al. (2011).”
• Accretion in the ρ-Ophiuchi pre-main sequence stars (2006, background): “The main difficulty comes from the large uncertainties that affect spectral types, due to the combination of high extinction and large veiling, even at near-IR wavelengths (e.g., LR99 and references therein; Doppman et al. 2003; Wilking et al. 2005).”
• Timescale of mass accretion in pre-main-sequence stars (2009, background): “Moreover, the result of Mohanty et al. (2005) might be contaminated by an older population of stars; objects in the periphery ofρ Oph core appear older than stars in the core itself (Wilking et al. 2005).”
• Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. I. Perseus (2005, background): “The embedded cluster is itself surrounded by a somewhat older population of stars extending over 1.3 deg2 (Wilking et al. 2005).”
• PROTOPLANETARY DISK STRUCTURES IN OPHIUCHUS. II. EXTENSION TO FAINTER SOURCES (2010, methodology): “Moreover, the central star is optically visible (Wilking et al. 2005) and the infrared SED shape is incompatible with a substantial envelope (Bontemps et al. 2001; Evans et al. 2003; Barsony et al. 2005).”