J/ApJ/717/L133 Formaldehyde maser flares in IRAS 18566+0408 (Araya+, 2010)
Quasi-periodic formaldehyde maser flares in the massive protostellar
object IRAS 18566+0408.
Araya E.D., Hofner P., Goss W.M., Kurtz S., Richards A.M.S., Linz H.,
Olmi L., Sewilo M.
<Astrophys. J., 717, L133-L137 (2010)>
=2010ApJ...717L.133A 2010ApJ...717L.133A
ADC_Keywords: YSOs ; Stars, masers ; Radio lines ; Interstellar medium
Keywords: ISM: individual objects (IRAS 18566+0408) - ISM: molecules -
masers - radio lines: general
Abstract:
We report results of an extensive observational campaign of the 6cm
formaldehyde maser in the young massive stellar object IRAS 18566+0408
(G37.55+0.20) conducted from 2002 to 2009. Using the Arecibo
Telescope, the Very Large Array, and the Green Bank Telescope, we
discovered quasi-periodic formaldehyde flares (P∼237 days). Based on
Arecibo observations, we also discovered correlated variability
between formaldehyde (H2CO) and methanol (CH3OH) masers. The
H2CO and CH3OH masers are not spatially coincident, as
demonstrated by different line velocities and high angular resolution
MERLIN observations. The flares could be caused by variations in the
infrared radiation field, possibly modulated by periodic accretion
onto a young binary system.
Description:
Using the 305m Arecibo Telescope, we monitored the 6cm H2CO maser
(JKaKc=110-111,νo=4829.6594MHz) in IRAS 18566+0408.
The pointing position was 18:59:09.98+04:12:15.6 (J2000). The
monitoring program had three intervals: 2006 May to 2007 April,
2008 January to 2008 May, and 2008 October to 2009 November.
A total of 48 runs were conducted.
Objects:
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RA (2000) DE Designation(s)
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18 59 10.02 +04 12 14.7 IRAS 18566+0408 = GAL 037.55+00.20
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 31 69 H2CO monitoring observations
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See also:
VI/51 : Collisional Excitation Rates of Formaldehyde (Green 1991)
J/MNRAS/391/869 : A mapping survey of massive CO cores (Guan+, 2008)
J/ApJ/669/435 : Arecibo Methanol Maser Galactic Plane Survey. II. (Pandian+,
2007)
J/A+A/432/737 : General Catalogue of 6.7GHz Methanol Masers (Pestalozzi+,
2005)
J/A+A/368/845 : Arcetri Catalog of H2O maser sources. Update. (Valdettaro+,
2001)
J/MNRAS/276/57 : IRAS Galactic star-forming regions. II. (Codella+ 1995)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "YYYY/MMM/DD" Date Date of observation
13 A1 --- l_Snu Limit flag on Snu
14- 18 F5.1 mJy Snu Flux density at 6cm (4829.6594MHz)
20- 23 F4.1 mJy e_Snu The RMS uncertainty in Snu
25- 31 A7 --- Tel Telescope identification (Arecibo,
VLA, or GBT) (1)
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Note (1): Data prior 2006 is from Araya et al. (2004ApJS..154..579A 2004ApJS..154..579A,
2005ApJ...618..339A 2005ApJ...618..339A, 2007ApJS..170..152A 2007ApJS..170..152A, 2008ApJS..178..330A 2008ApJS..178..330A).
The synthesized beams of our VLA observations in A, B, and C
configurations were approximately 0.5", 1.7", and 5", respectively.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 07-Jun-2012