J/ApJ/983/2 Blue blobs and Jellyfish galaxies catalog (Dey+, 2025)
Citizen Science Identification of Isolated Blue Stellar Systems in the
Virgo Cluster.
Dey S., Jones M.G., Sand D.J., Mazziotti N., Janowiecki S., Zeimann G.R.,
Bennet P.
<Astrophys. J. 983, 2 (2025)>
=2025ApJ...983....2D 2025ApJ...983....2D (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Clusters, galaxy ; Abundances ; Ultraviolet ; Photometry
Keywords: Star forming regions - Virgo Cluster -
Low surface brightness galaxies - Ram pressure stripped tails -
Dwarf galaxies
Abstract:
We present a catalog of 34 new candidate (13 high confidence)
isolated, young stellar systems within the Virgo galaxy cluster
identified through a citizen science search of public optical and
ultraviolet imaging. "Blue blobs" are a class of blue, faint,
isolated, extremely low stellar mass, and metal-rich star-forming
clouds embedded in the hot intracluster medium of the Virgo cluster.
Only six blue blobs were known previously and here we confirm an
additional six of our candidates through velocity and metallicity
measurements from follow-up optical spectroscopy on the Hobby-Eberly
Telescope (HET). Our 13 high confidence candidates (including the six
confirmed) have properties consistent with prior known blue blobs and
are inconsistent with being low-mass galaxies. Most candidates are
concentrated in relatively dense regions, roughly following
filamentary structures within the cluster, but avoiding its center.
Three of our candidates are likely the stellar counterparts of known
"optically dark" clouds of neutral hydrogen in the cluster, while a
further four are widely separated extensions to previously known blue
blobs. The properties of our new candidates are consistent with
previous conclusions that blue blobs likely originated from ram
pressure stripping events, however, their locations in
velocity-projected cluster-centric radius phase space imply that
their parent galaxies are not on their first infall into the cluster.
Through our ongoing follow-up program with HET we aim to confirm
additional candidates, however, detailed understanding of the stellar
populations and star formation histories of blue blobs will require
JWST observations.
Description:
Blue blobs are a novel type of stellar system discovered in the Virgo
cluster. A citizen science project was launched to identify these
systems and galaxies with jellyfish structure. This work presents the
results of that project.
Based on observations obtained with the Hobby-Eberly Telescope (HET),
which is a joint project of the University of Texas at Austin, the
Pennsylvania State University, Ludwig-Maximillians-Universitat
Munchen, and Georg-August Universitat Gottingen. The HET is named in
honor of its principal benefactors, William P. Hobby and Robert E.
Eberly.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 187 40 All Rank 1 and Rank 2 Blue Blobs Found in the
Virgo Cluster
table2.dat 49 56 All Jellyfish Candidates Found in the Main
Virgo Cluster through the Citizen Science Search
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Byte-by-byte Description of file:table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Name of the blue blob, BCHHMM+DDMM
13- 15 A3 --- Note Note (1)
17- 22 A6 --- BCName Short BC name for easier reference
within the paper
25- 35 A11 --- OName Name within a major catalog
38 I1 --- Rank [1/2] Rank of the blue blob
41- 42 I2 h RAh Right Ascension (J2000) of blue blob
44- 45 I2 min RAm Right Ascension (J2000) of blue blob
47- 50 F4.1 s RAs Right Ascension (J2000) of blue blob
53 A1 --- DE- Declination sign (J2000) of blue blob
54- 55 I2 deg DEd Declination (J2000) of blue blob
57- 58 I2 arcmin DEm Declination (J2000) of blue blob
60- 61 I2 arcsec DEs Declination (J2000) of blue blob
66- 70 F5.2 mag imag Apparent magnitude in i band
73- 76 F4.2 mag e_imag Uncertainty of apparent magnitude in i band
79- 83 F5.2 mag gmag Apparent magnitude in g band
86- 89 F4.2 mag e_gmag Uncertainty of apparent magnitude in g band
92- 96 F5.2 mag NUVmag ? Apparent magnitude in NUV band
99-102 F4.2 mag e_NUVmag ? Uncertainty of apparent magnitude
in NUV band
105-108 F4.2 [Msun] logMstar Blue blob stellar mass
111-114 F4.2 [Msun] e_logMstar Uncertainty of blue blob stellar mass
117-121 F5.2 [Msun/yr] logSFRNUV ? Blue blob NUV star formation rate
124-127 F4.2 [Msun/yr] e_logSFRNUV ? Uncertainty of blue blob NUV star
formation rate
129 A1 --- l_logMHI [<] Lower limit flag on blue blob HI mass
131-134 F4.2 [Msun] logMHI Blue blob HI mass
138-141 I4 km/s HRV-HI ? Blue blob HI velocity
145-148 I4 km/s HRV-Ha ? blob Halpha velocity
149-153 A5 --- n_HRV-Ha [No_Ha] No_Ha for No Hα
156-160 F5.2 --- [O/H] ? Blue blob metallicity
163-166 F4.2 --- e_[O/H] ? Uncertainty in blue blob metallicity
169-187 A19 --- BibCode Papers referenced bibcode
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Note (1): Note as follows:
a = Does not meet isolation criteria, see Section 2.4
b = HI mass and velocity uncertain as the HI counterpart may include
a nearby galaxy
c = Confirmed blue blobs
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Jellyfish candidate name, BCHHMM+DDMM
13- 18 I6 --- AGC ? UGC/AGC identifier
20- 30 A11 --- OName Name in a major catalog
32- 33 I2 h RAh Right Ascension (J2000) of Jellyfish candidate
35- 36 I2 min RAm Right Ascension (J2000) of Jellyfish candidate
38- 39 I2 s RAs Right Ascension (J2000) of Jellyfish candidate
41 A1 --- DE- Declination sign (J2000) of Jellyfish candidate
42- 43 I2 deg DEd Declination (J2000) of Jellyfish candidate
45- 46 I2 arcmin DEm Declination (J2000) of Jellyfish candidate
48- 49 I2 arcsec DEs Declination (J2000) of Jellyfish candidate
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Acknowledgements:
Swapnaneel Dey, swapnaneeldey(at)arizona.edu
Michael G. Jones, jonesmg(at)arizona.edu
References:
Jones et al., 2022ApJ...935...51J 2022ApJ...935...51J, Young, Blue, and Isolated Stellar Systems
in the Virgo Cluster. II. A New Class of Stellar System.
Jones et al., 2024ApJ...966L..15J 2024ApJ...966L..15J, Dark No More: The Low-luminosity Stellar
Counterpart of a Dark Cloud in the Virgo Cluster.
(End) Patricia Vannier [CDS] 29-Apr-2025