1. Multiplicity in the Aquila Star-Forming Region
Collaborators: Lisa Prato, Ian McLean, Quinn Konopacky, Andrea Ghez, Tom Ghez
Published in Rice et al and Prato et al. in press (Handbook of Star Forming Regions edited by Bo Reipurth)
Selection of the sample, which I describe in a moment, was motivated by these objects, AS 353A and B, one or both of which excite this Herbig-Haro object HH 32. The selection of the sample and the goals of this project were motivated by this intriguing system.
Hubble Heritage IMage
Emily L. Rice, UCLA
Multiplicity in Star Formation Workshop
May 17, 2007

2. Aquila SFR is eastern portion of Aquila Rift between Serpens, Vulpelcula & Scutum in the Galactic plane
Left plot: why Aquila hasn’t been studied
Right plot: why Aquila SHOULD be studied: ample material for star formation, very few stars known
Stars from left to right: HBC 294 (lower l), Par 21 (more distant), AS 353, HBC 684, HBC 681/682/683
Aquila Rift in Visible Light A. Mellinger (de Cicco 1999, Prato et al. in press)
Aquila Rift in Integrated 12CO
T. Dame (Prato et al. in press)
Molecular mass: 1.1 to 2.7 x 105 Msun (Dame & Thaddeus 1985, Dame et al. 1987, Straizys et al. 2003)
Virial mass: 2.6 x 105 Msun (Dame & Thaddeus 1985)
Many large & small dark clouds and molecular cores
Few known young stars

3. Radial velocity survey of known Aquila stars (Rice et al. 2006)
HBC 682
HBC 681
HBC 683
FG Aql/G3
High-resolution H-band spectra of nine systems (seven multi-epoch) using NIRSPEC on Keck II
Goals:
Search for spectroscopic binaries
Measure radial velocity to strengthen membership
determine other stellar properties to confirm youth & membership
The sample was chosen based on low mass, H alpha emission, and spatial proximity to AS The original sample was seven stars, then grew to nine through the discovery of a visual binary (HBC 682) and the accidental observation of FG Aql/G3. This 2MASS image shows a field containing five of the nine sample stars.
Results:
IR spectral types
Radial velocity & variability
Rad. Vel. Dispersion ~2 km/s
H-band 2MASS image (40” x 40”)

4. Results: HBC 682 identified as a triple systemK A
(vsini) B 1”
NIRC2 (Keck II)
~1” visual binary
HBC 682A is radial velocity variable over five epochs (2.25 yr baseline)

5. Results: possible low-mass companion to HBC 681K 1”
A. Ghez
Plug Quinn’s talk!!!
NIRC2 H and K images taken over a year apart
Flux ratio ~15 in both bands
H-K ~ 0.35: consistent with late-M spectral type (possible Brown Dwarf if real companion)
Need J for NIR colors, common proper motion

6. AS 353 is a known triple system
Mixed classical/weak-lined T Tauri system
B is subarcsecond binary (Tokunaga et al. 2004)
Age ≤ few million years (Prato et al. 2003; Rice et al. 2006)
Distance ~ 200±30 parsec (Rice et al. 2006)
A has rich emission line spectrum in optical (Eislöffel et al. 1990) & heavily veiled photospheric absorption lines in near-IR (Rice et al. 2006)
This is a mixed T Tauri system – the primary is a classical T Tauri with strong H alpha emission (150 ang.) and infrared excess, while the secondary, which has recently been resolved into a subarcsecond binary system, is a weak-lined T Tauri star. The age and the distance are still somewhat uncertain but are probably larger than the well-studied Taurus and Ophiucus star forming regions.
L’ image of AS 353 from Tokunaga et al. (2004)

7. Multi-epoch H-band spectra of AS 353 A from Rice et al. 2006
#’s correspond to line IDs in Rice et al. 2006
Orange lines are Fe, others are S, Ti, Ni, C, Si, OH
Radial velocity is non-variable over three epochs (2 yr baseline)
Radial velocity and common proper motion (Herbig & Jones 1983) indicate it is a bound pair with AS 353B

8. HBC 294 is a known is binary K1”
0.52” visual binary, PA=17º (Ageorges et al. 1994)
Optical and NIR emission lines in unresolved spectrum
Near-, mid-, and far-IR excesses suggest dust disk
Truncated disks suggested by low IRAS 100 m flux

9. Confirmed Aquila Members have a High Multiplicity Fraction
Object
HBC
Sp. Type
Multiplicity
Reference
AS 353A
292 K5
Single
Rice et al. 2006
AS 353B
685 M0
Binary
Tokunaga et al. 2004
V536 Aql
294 K7
Ageorges et al. 1994
FG Aql/G1
681
Binary?
unpublished
FG Aql/G2
682
Triple
FG Aql/G3 …
FH Aql
683
IRAS
684
Single?
As many as 13 objects in 7 systems!

10. Nebulosity around HBC 684 40” x 40” 2MASS H band Br continuum
(A. Weinberger)
It is apparent from these images that there is some nebulosity around this unusual emission-line object. We didn’t see this emission when we imaged it the slit-viewing camera on NIRSPEC. This is an interesting object that certainly warrants further study. (references in SIMBAD) N E
5’ x 5’ POSS II IR

11. Unexplained emission lines in spectrum of HBC 684 from Rice et al. 2006
Line ratios match K5 standard spectrum
Weak Hydrogen emission
UT 30 April 2007 spectrum still shows emission lines
Possible binary from NIRC speckle observations
Sep = , 30 mas, below diffraction limit of Keck telescope
PA =
Flux Ratio =

12. Conclusions
Aquila is a promising laboratory for the study of low-mass star formation
Of seven confirmed Aquila systems, there are:
Two triples (AS 353 & HBC 682)
One q~1 binary (HBC 294)
One possible low-mass companion (HBC 681)
Up to 13 objects total!
Multiplicity likely similar to Taurus for known members
Follow-up work:
H imaging of region to find more candidate members (ongoing)
high-resolution spectra of candidate members